ANNUAL REPORT 2013equs.org/sites/default/files/documents/eQusAnnualReport2013web3.… · PUBLICATIONS 103 – Journal Articles 104 APPENDIX 2 CONFERENCES 107 Unpublished Presentations

ANNUAL REPORT 2013

EQuS acknowledges the support of the Australian Research Council.

We also acknowledge the financial and in-kind support provided by our collaborating organisations:

Front Cover photo: A time lapse photo of the splitting of entangled photons by a polarizing beam splitter. Courtesy of PhD student Mr Alexander Buese ARC Centre of Excellence for Engineered Quantum Systems.

EQuS ANNUAL REPORT 2013 1

EQUS RESEARCH PROGRAMS 27

– Delivering on Grand Challenges 27

– Quantum Measurement and Control 28

– Quantum-Enabled Sensors and Metrology 28

– Synthetic Quantum Systems and Simulation 28

MAJOR RESEARCH PROJECTS IN 2013 31

Program: Quantum Measurement and Control

– Quantum Control with Trapped Ions 31

– Semiconductor Quantum Dots 36

– Non-Markovian Dynamics in Driven Quantum Systems 39

– Optomechanics 40

– Quantum Interfaces 42

– Plasmonics 43

– Coupling Superconducting Qubits to Sapphire Resonators 44

– Engineered All-Optical Quantum Switch and Router 45

– Hybrid High-Q Oscillators 46

Program: Quantum Enabled Sensors and Metrolgoy

– Using Non-Classical Light to Enhance Measurements 48

– Nanoparticles for Sensing and Bioimaging I 49

– Nanoparticles for Sensing and Bioimaging II 50

Program: Synthetic Quantum Systems and Simulation

– Quantum Matter 51

– Quantum Many Body Systems 53

– Quantum Phase Transitions and Simulation 55

– Superconducting Quantum Circuits 57

– Quantum Simulations and Boson Sampling 58

– Programmable Quantum Simulation 59

– Quantum Simulation with Quantum Optics 61

– Tensor Network Simulations 62

– Exotic Phases and Low-Dimensional Physics in Nano-Structured Arrays of Josephson Junctions 64

INTRODUCTION 3

– Overview 3

– Financial Support 3

DIRECTOR’S FOREWORD 4

ORGANISATION AND GOVERNANCE 5

– Centre Governance and Management Structure 5

– Advisory Board 6

– Program Managers (CI) Committee 7

– Scientific Advisory Committee 7

OUR VISION AND MISSION 9

– Objectives 9

EQUS STAFF AND STUDENTS 11

– Chief Investigators 11

– Management and Administration 16

– Research Fellows 17

– Research Assistants 17

– Students – PhD 18

– Masters 18

– Collaborators 19

INFRASTRUCTURE 21

– The Quantum Technology Laboratory The University of Queensland 21

– The Queensland Quantum Optics Laboratory The University of Queensland 21

– The Atom Optics Laboratory The University of Queensland 22

– The Superconducting Quantum Devices Laboratory The University of Queensland 22

– The Superconducting Single-Charge Device Laboratory (SSCDL) The University of New South Wales 23

– The Diamond Nanoscience Laboratory Macquarie University 23

– The QIRON Laboratory Macquarie University 24

– The Quantum Nanoscience Laboratory The University of Sydney 24

– The Frequency and Quantum Metrology Laboratory The University of Western Australia 25

– The Quantum Control Laboratory The University of Sydney 25

CONTENTSKEY PERFORMANCE INDICATORS 67

– Research Findings 67

– Research Training and Professional Education 69

– International, National and Regional Links and Networks 74

– End-User Links 84

– Organisational Support 93

– Collaborating Institutions 97

– Income Derived from Other Sources 98

STRATEGIC DIRECTIONS 2014 101

– Quantum Measurement and Control 101

– Quantum-Enabled Sensors and Metrology 102

– Synthetic Quantum Systems and Simulation 102

APPENDIX 1

PUBLICATIONS 103

– Journal Articles 104

APPENDIX 2

CONFERENCES 107

– Unpublished Presentations 108

APPENDIX 3

FINANCIAL STATEMENT 114

– EQuS Financial Statement 115

– Financial Outlook 116

APPENDIX 4

KEY RESULT AREAS AND STANDARD PERFORMANCE MEASURES TABLE 2013 117

– Research Findings 118

– Research Training and Professional Education 118

– International, National and Regional Links and Networks 119

– End-User Links 119

– Organisational Support 119

– Governance 120

– National Benefit 120

2 EQuS ANNUAL REPORT 20132 EQuS ANNUAL REPORT 2013


2013 EQuS INCOME

INTRODUCTION

AU$3,833,949

AU$1,060,315

AU$14,563

AU$ 600,000 AU$200,000

AU$490,000

AU$45,600

ARC CoE Grant

Macquarie University

Other Grants

Overseas Government Organisation

Partner Organisations

The University of New South Wales

The University of Queensland

The University of Sydney

The University of Western Australia

AU$50,000AU$93,625

Overview

The ARC Centre of Excellence for Engineered Quantum Systems (EQuS) seeks to move from Quantum Science to Quantum Engineering – building and crafting new quantum technologies. In collaboration with the internationally renowned Physics groups of The Universities of Queensland, Sydney, Western Australia, New South Wales and Macquarie University, EQuS provides the world’s first focused research program on systems engineering in the quantum regime. EQuS is addressing fundamental questions about the benefits and limits of quantum technologies, developing strategies for producing novel quantum-enhanced devices, and exploring new emergent physical phenomena that arise only in the presence of complex, integrated quantum systems.

Financial Support

The Centre’s main source of funding is the Australian Research Council through the Centres of Excellence program. The ARC provides $3.5 million per annum, and the administering institution, The University of Queensland, and the collaborating institutions The University of Sydney, Macquarie University, The University of Western Australia and the University of New South Wales contribute ~$1.2 million in cash contributions per year.


We are now reaping the rewards of the novel collaborations that an ARC Centre is designed to produce.

A new EQuS project to develop new quantum devices based on the microwave response of quantum Hall fluids is underway at The University of Sydney. In a recently established collaboration with researchers at Microsoft Station-Q, they have proposed a new approach for detecting exotic quasiparticles, including their braiding statistics – results are published in Physical Review B.

In 2013, we experimentally realised these devices and demonstrated a novel measurement technique. Our future goals include exploiting the relevant physical processes to develop microwave circulators – important devices for many quantum experiments, as well as establishing hybrid systems that transduce microwave photons to quantum Hall quasiparticles.

In a collaboration between CI Professor Michael Tobar at The University of Western Australia and CI Dr Thomas Volz at Macquarie University, the UWA node will build the first proto-type microwave resonator capable of addressing the spin of an individual NV centre. The cavity was built at UWA using low-loss high-permittivity rutile, enabling resonant frequencies of 2-3 GHz in a cm-scale device. First experimental measurements carried out in 2013 demonstrated successful excitation of NV centres using the resonator’s microwave field, and a manuscript is currently under preparation.

The goal in the future will be to perform Optically Detected Magnetic Resonance and Time-Resolved Spin-Rotation measurements, with further exchange funding obtained to undertake 3D tomography using this technique.

This past year has seen an increasing emphasis on engineered

DIRECTOR’S FOREWORD

PROFESSOR GERARD MILBURN Director, ARC Centre of Excellence for Engineered Quantum Systems

quantum systems in the calls for grant applications from funding organisations around the world.

In November I spoke at a meeting held at the Royal Society Centre at Chicheley Hall convened to discuss a possible new funding initiative in quantum technologies in the United Kingdom. There is growing awareness that a number of quantum technologies are within five years of significant commercial deployment.

As a result of this meeting in December 2013 The Chancellor of the Exchequer, George Osborne, confirmed £270 million worth of investment in Quantum technology. Part of this will go to the research councils who will fund one or more quantum technology hubs in UK universities.

In Europe there is now a new funding program on quantum simulations, a core part of our Centre’s activities.

EQuS is very well placed to develop new collaborations with researchers in the UK and Europe that will be enabled by these new funding schemes. This will ensure EQuS remains internationally competitive and continues to hold a position of leadership in quantum technology.


ORGANISATION AND GOVERNANCE

Centre Governance and Management Structure

In 2011, the Centre was formed as a partnership of the collaborating institutions under a formal Centre Agreement, with The University of Queensland as the administering institution.

EQuS ORGANISATIONAL CHART

IP Committee Scientific Advisory Committee

Advisory Board

Research Director

Chief Operations Officer

AdministrationNode Managers Committee

EQuS acknowledges the support of the Australian Research Council.

We also acknowledge the financial and in-kind support provided by our participating organisations – The University of Queensland, The University of Sydney, Macquarie University, The University of Western Australia, The University of New South Wales.

Chief Investigators, Research Fellows and Students

Program (CI) Committee

6 EQuS ANNUAL REPORT 2013


Advisory Board

The Advisory Board assists Centre management by contributing to the development of strategies and vision for the future relative to the proposed goals and objectives of the Centre, and by serving as a vehicle for creating better linkages between academia, industry and government.

The Advisory Board met on March 8 and October 11 in 2013.

In 2013 the Centre’s Advisory Board comprised:

Dr Rowan Gilmore (Chair)

CEO EM Solutions Pty Ltd Brisbane

Dr Ben Greene

Group CEO Electro Optic Systems (EOS) Canberra

Mr Rick Wilkinson

COO – Eastern Region Australian Petroleum Production & Exploration Association Brisbane

Dr David Pulford

Senior Research Scientist DSTO Canberra

Mr Vic Dobos

CEO Australian Science Teachers Association (ASTA) Canberra

Professor Max Lu

DVC Research The University of Queensland Brisbane

Professor Jim Piper

DVC Research Macquarie University Sydney

Professor Jill Trewhella

DVC Research The University of Sydney Sydney

Professor Robyn Owens

DVC Research The University of Western Australia Perth

Professor Les Field

DVC Research The University of New South Wales Sydney

Professor Gerard Milburn

EQuS Research Director (ex officio) The University of Queensland Brisbane

Professor Andrew White

EQuS Deputy Director (ex officio) The University of Queensland Brisbane

Ms Marianne Johnston

EQuS COO (ex officio) The University of Queensland Brisbane

CI meeting 2013 at the University of Sydney



Program Managers (CI) Committee

The Centre Program Managers or CI Committee is responsible for a process of continuous quality assessment of the major programs of the Centre, the provision of feedback to the Advisory Board and Scientific Advisory Committee on the progress being made in the Centre’s research programs and against its research objectives and milestones. It works to provide academic leadership and cohesion within the Centre, and oversees continuity of research approach and communication between research nodes.

The Centre Program Managers Committee comprises the Chief Investigators at the participating collaborating organisations (UQ, USyd, MQ, UWA and UNSW) and the Centre Chief Operations Officer, and is chaired by the Centre Director.

The Centre’s CI Committee met on the following dates in 2013:

Date Venue

8 February The University of Queensland

10 May The University of Sydney

2 August The University of Queensland

8 November Macquarie University

Scientific Advisory Committee

The Scientific Advisory Committee (SAC) comprises the Research Director, the Advisory Board Chair, international scientists and experts in quantum science and engineering and an eminent international researcher as an independent chair. The SAC is responsible for advising the Centre Research Director and the Centre Program Managers or CI Committee on the direction of research undertaken within the Centre, as well as providing guidance on emerging international trends and scientific developments as they relate to the major programs of the Centre.

The Centre’s Scientific Advisory Committee comprises:

Professor Sir Peter Knight FRS (Chair)

The Kavli Royal Society International Centre United Kingdom

Professor Mikhail Lukin

Harvard University United States

Professor Rainer Blatt

University of Innsbruck Austria

Professor Gerard Milburn

The University of Queensland Australia

Professor John Clarke

University of California, Berkeley United States

Dr Rowan Gilmore

EM Solutions Pty Ltd Australia

EQuS and Friends Workshop 2013

Photo centre: Scratched spiral inductor, fabricated from silver deposited on a niobium chip. Courtesy of PhD student Alice Mahoney (EQuS photo competition).


Microscopic photo of a semiconductor (EQuS photo competition).



OUR VISION

In the ARC Centre for Engineered Quantum Systems (EQuS), we are engineering the quantum future. By discovering how to control and exploit the most exotic phenomena in quantum theory, our Centre is building a new discipline with the potential to radically transform technology.

OUR MISSION

To exploit the vast resources of the quantum realm to produce new capabilities, new technologies, and new science through the creation of designer quantum systems.

Objectives – To establish a world-leading research community driving the

development of quantum technologies, with Australia as the focus of international efforts

– To train a generation of young scientists with the skills needed to lead the future of quantum technology development

– To stimulate the growth of world-class Australian industries using innovative quantum technologies developed from cutting-edge research

– To demonstrate the potential and capabilities of engineered quantum technologies to the next generation of scientists and the wider community


Xanthe Croot in the Quantum Nanoscience Laboratory at The University of Sydney.


EQuS STAFF AND STUDENTS


RESEARCH DIRECTOR PROFESSOR GERARD MILBURN obtained a PhD in theoretical Physics from the University of Waikato in 1982 for work on squeezed states of light and quantum nondemolition measurements. Professor Milburn is a Fellow of the Australian Academy of Science and The American Physical Society. He has worked in the fields of quantum optics, quantum measurement and stochastic processes, atom optics, quantum chaos, mesoscopic electronics, quantum information and quantum computation. More recently, he initiated collaboration with Philosophy at The University of Queensland to study the nature of causation in a quantum world.

DEPUTY DIRECTOR AND NODE MANAGER – PROFESSOR ANDREW WHITE was raised in a Queensland dairy town, before heading south to the big smoke of Brisbane to study chemistry, maths, physics and, during the World Expo, the effects of alcohol on uni students from around the world. Deciding he wanted to know what the cold felt like, he first moved to Canberra, then Germany—completing his PhD in quantum physics—before moving on to Los Alamos National Labs in New Mexico where he quickly discovered that there is more than enough snow to hide a cactus, but not nearly enough to prevent amusing your friends when you sit down. Over the years he has conducted research on various topics including shrimp eyes, nuclear physics, optical vortices, and quantum computers. He likes quantum weirdness for its own sake, but his current research aims to explore and exploit the full range of quantum behaviours—notably entanglement—with an eye to engineering new technologies and scientific applications.

ASSOCIATE PROFESSOR WARWICK BOWEN leads the Queensland Quantum Optics Group at The University of Queensland. His group’s research is primarily focused on applications of silicon chip based optical microresonators in fundamental science, photonics and sensing. Warwick’s research background is in quantum optics and photonics, and particularly in the emerging fields of quantum information science and quantum optomechanics. These fields rely critically on the development of new techniques to generate and control non-classical states of systems such as optical fields, atoms, and micromechanical cantilevers. Warwick has worked on each of these systems, aiming to investigate their quantum behaviour, use it in quantum technologies, and spin off real-world applications.

Chief Investigators




PROFESSOR HALINA RUBINSZTEIN-DUNLOP’S research interests are in the fields of atom optics, laser micromanipulation, nano optics, quantum computing and biophotonics.She has long standing experience with lasers, linear and nonlinear high-resolution spectroscopy, laser micromanipulation, and atom cooling and trapping. She was one of the originators of the widely used laser enhanced ionisation spectroscopy technique and is well known for her recent work in laser micromanipulation. She also has been working (Nanotechnology Laboratory, Göteborg, Sweden) in the field of nano- and microfabrication in order to produce the microstructures needed for optically driven micromachines and tips for the scanning force microscopy with optically trapped stylus. Recently she led the team that observed dynamical tunnelling in quantum chaotic system. Additionally Prof. Rubinsztein-Dunlop has led the new effort into development of new nano-structured quantum dots for quantum computing and other advanced device related applications.

DR IAN MCCULLOCH leads the Tensor Network Algorithms group that works in computational tensor network algorithms for one- and two-dimensional

quantum systems, and applications to condensed matter, ultra-cold atomic gases and engineered quantum systems. The current focus of the group is DMRG and MPS algorithms for infinite 1D systems, applications of MPS to physically relevant simulations (especially non-equilibrium), groundstates and time evolution in 2D PEPS, fermionic tensor networks. The group has ties to experimental groups at The University of Queensland and other institutions. Ian was born in Tasmania, and graduated with a BSc from the University of Tasmania in 1997. After a PhD in condensed matter physics at ANU, he moved overseas, firstly to the Lorentz Institute in Leiden, the Netherlands, and then to RWTH-Aachen University in Germany. In 2007 he moved back to Australia to take up a postdoctoral fellowship, and later a lecturing position, at The University of Queensland. Ian’s research interests are numerical techniques for simulating quantum many-body systems, and he is the author of a large suite of software tools that are used by several research groups around the world.

DR TOM STACE completed his PhD at the Cavendish Lab, University of Cambridge in the UK on quantum computing, followed by postdoctoral research at the Department of Applied Mathematics and Theoretical Physics, also at Cambridge. During this time he was a fellow at Queens’ College, known for its eclectic mix of medieval, tudor and victorian architecture. He has been a researcher at The University of Queensland since 2006, firstly on an ARC Postdoctoral Research Fellowship, and latterly with an ARC Research Fellowship. His research has largely focused on applying

methods from quantum optics to solid state devices for use in quantum information applications, and more recently on error correction protocols. He also works on high precision measurement in collaboration with experimental colleagues at UWA, in a project whose ultimate aim is to contribute to the international definition of Boltzmann’s constant, and some biophysics.

DR ARKADY FEDOROV completed his PhD at Clarkson University, United States in 2005. His research work was primarily on theoretical aspects of quantum information science and decoherence in solid state systems. He was then appointed a postdoctoral fellow at Karlsruhe Institute of Technology, Germany working on a theory of superconducting quantum circuits in application to quantum computing and quantum optics phenomena. From 2007-2010 he worked at the Delft University of Technology, The Netherlands conducting experiments with superconducting flux qubits. Later he became a research scientist in ETH Zurich to continue research in the area of superconducting quantum devices. Starting January 2013 he is a group leader in the School of Mathematics and Physics at The University of Queensland. His group studies quantum phenomena in systems consisting of superconducting artificial atoms, microwave resonators and mechanical oscillators.

Chief Investigators (continued)




NODE MANAGER – PROFESSOR STEPHEN BARTLETT is a Professor in the School of Physics at The University of Sydney, and part of the Quantum Information Theory group. He is a theoretical physicist, pursuing fundamental research in quantum physics. Professor Bartlett’s particular focus is on quantum information theory, including the theory of quantum computing, as well as the foundational issues of quantum mechanics. He completed his PhD in mathematical physics at the University of Toronto in 2000. After moving to Australia, he directed his research to the theory of quantum computing, first as a Macquarie University Research Fellow and then as an ARC Postdoctoral Research Fellow at the University of Queensland. Since 2005, he has led a research program in theoretical quantum physics at The University of Sydney, with interests spanning quantum computing, quantum measurement and control, quantum many-body systems, and the foundations of quantum theory.

ASSOCIATE PROFESSOR MICHAEL BIERCUK is an experimental physicist and the Primary Investigator in the Quantum Control Laboratory at The University of Sydney. Michael’s specialties include quantum physics, quantum control, quantum error suppression, ion trapping, nanoelectronics, and precision metrology. Michael was educated in the United States, earning his undergraduate degree from the University of Pennsylvania, and his Master’s and Doctoral degrees from Harvard University. Today, Michael runs a research group performing cutting-edge experiments using trapped atomic ions as a model quantum system. His expertise has been recognized by numerous technical appointments, awards, and media appearances. He is a regular contributor to both the technical literature and the popular press, providing expert commentary on issues pertaining to science policy and the role of science in society.

ASSOCIATE PROFESSOR ANDREW DOHERTY is a theoretical physicist and senior lecturer with research interests in quantum control and quantum information at The University of Sydney. He holds an Australian Research Council Future Fellowship in the School of Physics at The University


of Sydney. He received a BSc (Hons) in Physics from the University of Canterbury in 1995 and his PhD in quantum optics under the supervision of Professor Dan Walls at The University of Auckland in 2000. From 2000 to 2003 he was a postdoctoral researcher at the California Institute of Technology and from 2003 to 2010 he was at the School of Mathematics and Physics at The University of Queensland.

PROFESSOR DAVID REILLY is the Director of the Quantum Nanoscience Laboratory at The University of Sydney where he leads a group of 7 PhD students and 2 postdoctoral research fellows. The focus of his research is the development of enabling technology to control condensed matter systems at the quantum level. Reilly’s niche is the interface between fundamental quantum science research and technical solutions that typically involve microwave electronics, cryogenics, nanofabrication, and engineering expertise. Before his appointment at Sydney, Professor Reilly was a Research Fellow in Physics at Harvard University, USA. His PhD is in Physics from the University of New South Wales, Australia.




NODE MANAGER – PROFESSOR JASON TWAMLEY is a Professor of Quantum Information Science at the Department of Physics and Astronomy at Macquarie University. He is a theorist who works in quantum science and has worked on topics ranging from the theory of quantum wormholes in quantum cosmology through to the theoretical designs for superconducting quantum devices. Professor Twamley believes that the world is essentially quantum mechanical in nature and we should therefore learn the fascinating properties of this quantum world and use these properties to create new science and technology. He is also Director of the MQ University for Quantum Science & Technology (QSciTech).

ASSOCIATE PROFESSOR GABRIEL MOLINA-TERRIZA is an Associate Professor of the Physics and Astronomy Department at Macquarie University and an Australian Research Council Future Fellow. At Macquarie University he is the group leader of QIRON (Quantum InteRactiOns with Nanoparticles). His research focuses on the spatial properties of light and uses the spatial modes of light as a tool to probe the properties of nanostructures. In his group, a

team of 6 PhDs and 2 post-docs is exploiting engineered quantum states of light to better understand the interaction of light and matter at the nanoscale. Experimentally combining the techniques of quantum optics and the new methods available in nanophotonics allows for the design of innovative biosensing capabilities and new measuring techniques.

DR THOMAS VOLZ is a senior lecturer at Macquarie University specializing in solid-state quantum optics and quantum photonics. During his PhD, he carried out experiments on ultracold atomic and molecular quantum gases in optical lattices in the group of Prof. Gerhard Rempe at the Max-Planck Institute of Quantum Optics in Garching (Germany). He was awarded his PhD in 2007 through the Technical University of Munich (Germany). Afterwards Dr Volz changed fields and joined Prof. Atac Imamoglu’s Quantum Photonics Group at ETH Zurich (Switzerland) where he carried out experiments on semiconductor cavity QED. At Macquarie University, Dr Volz continues his research in semiconductor quantum optics, and at the same time leads the diamond nanoscience lab with a research focus on quantum sensing with nano-diamond. Dr Volz was appointed an EQuS CI in January 2013.

ASSOCIATE PROFESSOR GAVIN BRENNEN is an Associate Professor of the Physics and Astronomy Department at Macquarie University. Gavin believes that nature is a wondrous place and an unfinished product. As a result, his main interests are how to use the physical laws we know, particularly quantum mechanics, to probe in ever more exquisite detail the manifestations of nature -- from elementary interactions to collective behaviour of complex many particle systems. His more general research interests are quantum information theory, coherent control of atomic/molecular/optical systems, topological order and topological quantum computation.

ASSOCIATE PROFESSOR ALEXEI GILCHRIST is a theoretical physicist in the research areas of quantum optics and quantum information. He received his PhD from Waikato University (New Zealand) in 1997 under the supervision of Professor Crispin Gardiner. Moving to Australia in 2001 as a New Zealand FRST Fellow, he remained in Australia as a research fellow for the ARC CoE for Quantum Computer Technology until becoming part of the faculty at Macquarie University in 2007. Associate Professor Gilchrist was appointed as an EQuS CI in 2011.




NODE MANAGER - PROFESSOR MICHAEL TOBAR is currently an ARC Laureate Fellow with the School of Physics at the University of Western Australia. He received his PhD degree in physics from the University of Western Australia in 1994. His research interests encompass the broad discipline of frequency and quantum metrology, precision measurements, and precision tests of the fundamentals of physics. Professor Tobar has had many career highlights since graduating including the award of the Barry Inglis medal (2009) and the Australian Institute of Physics Boas medal (2006) and the Alan Walsh medal (2012). During 2007 he was elevated to Fellow of the Institute of Electrical and Electronics Engineers (IEEE), during 2008 the Australian Academy of Technological Sciences and Engineering and during 2012 the Australian Academy of Science. Professor Tobar also received a citation from the Australian Learning and Teaching Council for inspiring research students to reach their full potential and transform to successful research scientists through participation in ground-breaking research.


NODE MANAGER - PROFESSOR TIMOTHY DUTY leads the Laboratory for Superconducting Single-Charge Devices at The University of New South Wales in Sydney, which focuses on experiments that explore and exploit the quantum behaviour of single-electrons and Cooper-pairs in nano-structured superconducting devices at millikelvin temperatures---with particular expertise using microwave and radio-frequency measurement techniques. Members of his laboratory also concentrate on nano-fabrication processing of superconducting devices at the UNSW node of the Australian National Fabrication Facility (ANFF).

Tim grew up in the hills of southwestern Virginia in the US, and received a BSc degree in Physics from Virginia Tech, followed by a MSc degree and a PhD in Physics from the University of British Columbia in Canada. Tim was a postdoc at Chalmers University of Technology in Gothenburg, Sweden, before becoming an Assistant Professor there in the Department of Microtechnology and Nanoscience. While at Chalmers, Tim worked on superconducting charge qubits and quantum metrological experiments aimed at current-to-frequency conversion using nano-structured superconducting devices. Prior to his appointment at UNSW, Tim was a Senior Lecturer at the University of Queensland.






CHIEF OPERATIONS OFFICER – MS MARIANNE JOHNSTON oversees the day-to-day management of the Centre assuming responsibility for the Centre’s reporting requirements, research operations and planning, and the administration of financial, human and physical resources.

BUSINESS SUPPORT MANAGER – MR ERIC PHAM’S primary role is to provide financial management and administrative support and advice to the Centre Director and Chief Operations Officer in managing financial and selected human resource functions of the Centre.

COMMUNICATION AND OUTREACH OFFICER (JANUARY TO OCTOBER) – MS LYNELLE ROSS is passionate about embracing new technology to deliver key messages and outcomes for EQuS. Lynelle holds a Bachelor of Multimedia from Griffith University and is part-way through completing a Masters in Organisational Communication.

EXECUTIVE SUPPORT OFFICER – MRS RUTH FORREST provides administrative and secretarial support to the Centre Director and Chief Operations Officer, and secretariat support to the Centre Advisory Board.

ADMINISTRATION OFFICER – MRS EMMA LINNELL provides a high level of customer service and broad administrative support to staff, students and visitors of the EQuS Centre. Emma has a particular focus on Deputy Director Andrew White’s research group ensuring it runs efficiently and effectively.


USYD NODE ADMINISTRATOR - MS LEANNE PRICE provides financial and administrative support to The University of Sydney node of EQuS & The University of Sydney Quantum Physics Group.


MQ NODE ADMINISTRATOR - MRS LYNNE COUSINS provides a high level of customer service and broad administrative support to staff, students and visitors of the EQuS Node at Macquarie University.


UWA NODE ADMINISTRATOR - MS ADIA YU provides a high level of customer service and broad administrative support to staff, students and visitors of the EQuS Node at The University of Western Australia.

Management and Administration



Research Fellows Research Assistants


– Uzma Akram – Matthias Baur – Matthew Broome – Robin Cole – Gregory Crosswhite – Alessandro Fedrizzi – Marcus Jerger – David McAuslan – Pascal Macha – Clemens Mueller – Casey Myers – Tyler Neely – Marcelo Pereria de Almeida – Jacopo Sabbatini – Stuart Szigeti – Till Weinhold – Fei Zhan

The University of Sydeny

– Sylvain Blanvillain – Steven Flammia – Torsten Gaebel – Stephen Gensemer – David Hayes – Michael Lee – Aroon O’Brien – Karsten Pyka – Andres Reynoso


– Stefania Castelletto – Mathieu Juan – Nitin Nand – Peter Rohde – Suhkbinder Singh – Eugene Tan – Ke Yu Xia


– Karim Benmessai – Daniel Creedon – Yaohui Fan – Maxim Goryachev


– Karin Cedergren – Sergey Kafanov – Jean-Loup Smirr


– Thomas Carey


– Ian Conway Lamb – John Hornibrook


– Alex Barbara – Elizabeth Camilleri


– Stephen Osborne


– Kari Pihl



Students – PhD


– Kirill Afanasyev – Sahar Basiri Esfahani – James Bennett – Devon Biggerstaff – Andrew Bolt – George Brawley – Janani Chander – Bixuan Fan – Adil Gangat – Geoffrey Gillett – Glen Harris – Phien Ho – Kiran Kholsa – Nicholas McKay-Parry – Markus Rambach – Yarema Reshitnyk – Martin Ringbauer – Juan Loredo Rosillo – Thomas Milburn – Andrew Ringsmuth – Seyed Saadatmand – Devin Smith – Alexander Szorkovszky – Michael Taylor


– Rafael Alexander – Harrison Ball – Courtney Brell – Jacob Bridgeman – Simon Burton – James Colless – Xanthe Croot – Andrew Darmawan – Natasha Gabay – Todd Green – John Hornibrook – Alice Mahoney – Matthew Palmer – Ewa Rej – Alexandr Sergeevich – Alexander Soare – William Soo – Maki Takahashi – David Waddington – Joel Wallman – Matthew Wardrop


– Ayeni Babatunde – Alexander Buese – Mauro Cirio – Tommaso Demarie – Ivan Fernandez-Corbaton – Faraz Inam – Clara Javaherian – Laurie Lehman – Keith Motes – Andrea Tabachinni – Hossein Tavakoli-Dinani – Nora Tischler – Ke Yu Xia


– Romain Bara-Maillet – Jeremy Bourhill – Natalia Do Carmo Carvalho – Warrick Farr – Md Akhter Hosain – Nikita Kostylev

Masters


– Thomas Guff – Daniel Lombardo – Trond Linjordet – Reece Roberts – Andrew Wood – Matthew van Breugel


– Dominic Else – Dominic Williamson



Collaborators

EQuS gratefully acknowledges the contributions of the following individuals associated with our administering, collaborating and partner organisations:

– Dr Alberto Amo – Prof. Marcus Aspelmeyer – Dr Jose Aumentado – Dr Cyril Branciard – Prof. Joachim Brand – Dr Carlo Bradac – Dr Thomas Barthel – Prof. Iwo Bialynicki-Birula – Assoc. Prof. C J Bolech – Dr John Bollinger – Dr Ben Brown – Prof. Carlton Caves – Mr C Y Chen – Ming-Chiang Chung – Assoc. Prof. Aashish Clerk – Prof. Matthew Davis – Prof. Jonathan Dowling – Prof. Milton Feng – Prof. Shangqing Gong – Prof. Arthur Gossard – Mr Jad Halimeh – Dr Fabian Heidrich-Meisner – Prof. Matt James – Prof. Fedor Jelezko

– Ms Ngaire Jones – Dr Ivan Kassal – Mr Stefan Kessler – Prof. Myungshik Kim – Prof. Martina Knoop – Prof. Jerzy Krupka – Prof. Eugene Ivanov – S Langer – Dr Jean-Michel Le Floch – T Liu – Mr Jing Lu – Prof. Charles Marcus – Prof. Florian Marquardt – Dr James McLouglin – Dr Terry McRae – Dr Nick Menicucci – Mr Steven Naboicheck – Dr Akisma Miyake – Dr William D Oliver – Assoc. Prof. Giuliano Orso – Prof. Christian Ospelkaus – Dr Jiannis Pachos – Dr Giandomenico Palumbo – Prof. David Poulin

– Prof. Romain Quidant – Prof. Tim Ralph – Dr Joseph Renes – Assoc. Prof. Marcos Rigol – Prof. Ulrich Schollwoeck – Prof. Robert Scholten – Dr Eoin Sheridan – Prof. Christine Silberhorn – Mr Adam Sirois – Mr Ray Simmonds – Prof. Enrique Solano – Dr Vid Stojevic – Dr Luca Tagliocozzo – Dr Kirsty Vernon – Prof. Frank Verstraete – Dr Michael Vanner – Prof. Guifre Vidal – Dr Xavier Vidal – Mr Anton Wollert – Dr Wan Li Yang – Sang-Keet Yip – J H Zhou – Prof. Peter Zoller


Optical microscopy calibration of a pentium 90 chip. Courtesy of PhD student Alice Mahoney (EQuS photo competition).



INFRASTRUCTURE

Our Centre of Excellence includes world-leading experimental infrastructure focused on a broad spectrum of technologies. Our efforts represent the absolute cutting-edge of capability in quantum control and quantum systems engineering.

The Quantum Technology LaboratoryThe University of Queensland

The Quantum Technology Laboratory is focused on emulating both natural and engineered quantum systems by using quantum photonics, a proven and flexible architecture for investigating exotic quantum phenomena, to enable new applications from secure communications through to improved metrology. The Laboratory has extensive quantum photonics facilities, including the world’s highest-efficiency entangled photon source, integrated photonic circuits, and highly efficient cryogenic calorimeters that can be used to count individual photons.

The Queensland Quantum Optics LaboratoryThe University of Queensland

The Queensland Quantum Optics Laboratory undertakes research in the quantum physics of micro- and nano-scale optical devices, with the aims of both testing fundamental physics, and developing quantum technologies with future applications in metrology, communication, and computation. Our research is primarily based around optical architectures integrated onto silicon chips compatible with current-day fibre optic systems. These architectures provide a test-bed from which we can study a wide

range of quantum processes including entanglement and non-locality, and quantum optomechanical systems. The robustness and scalability of the systems used offer potential for the investigation of large-scale quantum systems and phenomena. The lab has Australia’s only fabrication facilities for silicon chip based ultrahigh quality optical microcavities, and one of only a few such facilities in the world. The lab also has cryogenic facilities allowing operation of quantum devices at temperatures as low as 0.3 K; multiple laser sources; and a range of radio frequency test and measurement systems.

Staff at The Queensland Quantum Optics Laboratory


The Atom Optics LaboratoryThe University of Queensland

The Atom Optics Laboratory at the University of Queensland explores applications of ultracold degenerate atomic systems. These include problems of fundamental physics interest, utilising ultracold atoms to produce emulations of other quantum systems and classical/quantum phase

transitions. We are currently developing a Bose-Einstein condensate apparatus utilising Rubidium (87Rb) and Potassium (41K) atoms to form a dual bosonic BEC. This apparatus centres around a custom-built all glass ultra-high vacuum chamber, allowing a high degree of optical access and facilitating high resolution imaging. Manipulation of the atomic ensemble through the use of configurable dipole potentials and magnetic fields yield the high degree of control necessary for emulation experiments.

Hybrid quantum systems, in which atoms are coupled to opto-mechanical resonators, are also being developed in collaboration with the group of Assoc. Prof. Warwick Bowen. Using our in-house expertise in pulling fibre tapers, a cold atom trap can be constructed. As the cold atoms interact strongly with the light propagating along the fibre, this light can then be utilised for external coupling of the atoms to other systems. Additionally, our group explores the applications of ultracold atoms to precision sensing, focusing on the measurement of rotation.

The Superconducting Quantum Devices LaboratoryThe University of Queensland

Superconducting quantum circuits are artificial structures with a possibility to design and engineer their key properties. These unique features have made these engineered systems to be one of the most promising candidates for realizing a quantum computer in solid state, have allowed for exploration of quantum optical phenomena on-chip and have facilitated the implementation of a quantum control of a nanomechanical degree of freedom.

Superconducting Quantum Devices Laboratory aims at establishing fabrication and measurement techniques for the next generation of superconducting nanodevices consisting of superconducting qubits or artificial atoms, microwave transmission lines and high quality superconducting resonators.

The heart of the Atom Optics laboratory experiment is a customised ultra-high vacuum (UHV) system. A cold atom beam produced in the 2D magneto-optical trap (MOT) is collected in the 3D-MOT, producing a cloud of 109 rubidium atoms one ~1/10,000th of a degree Kelvin above absolute zero.

By using strong coupling strength between single microwave photon and a superconducting qubit in these networks, one can realize a plethora of novel light-matter interaction regimes. In addition, superconducting circuits can integrate nanomechanical quantum devices opening avenues for quantum control of mechanical degree of freedom.

The laboratory enables ultra-low noise electronic measurements at milliKelvin temperatures and contains an Oxford instruments DR200 dilution refrigerator and a complete set of test and measurement microwave equipment.

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Left: Oxford instruments DR200 dilution refrigerator prepared for measurements with superconducting quantum bits. Right: Different stages of an open dilution refrigerator with microwave wiring and a magnetic shield.


The Superconducting Single-Charge Device Laboratory (SSCDL)The University of New South Wales

In 2011, a new low temperature laboratory, focused on experiments with nano-structured superconducting quantum devices based on Josephson junctions, was established at The University of New South Wales by Tim Duty. This laboratory became part of EQuS in 2012, and has since expanded its facilities to include two BlueFors cryogen-free dilution refrigerators which enable ultra-low noise microwave and radio-frequency measurements at milliKelvin temperatures.

Since 2011, the laboratory has invested heavily in developing new nano-fabrication processes for superconducting devices at the UNSW node of the Australian National Fabrication Facility. The development of such nano-fabrication processes from the ground up is a very complex and labor-intensive task, therefore

the SSCDL is proud to have achieved production of working and reliable Josephson devices as of late 2013. This achievement significantly expands the capabilities for EQuS and other Australian-based science.

As of the beginning of 2014, EQuS researchers at UNSW can now produce superconducting devices on par with the leading laboratories around the world.

The Diamond Nanoscience LaboratoryMacquarie University

The Diamond Nanoscience Laboratory is based at Macquarie University and is part of the Quantum Materials and Applications Group (QMAPP) led by the new EQuS CI Dr Thomas Volz. The research on nano-diamonds lies at the interface of quantum physics, nanotechnology and material science. A major research direction in the diamond lab is the use of NV-centre spins for magnetic sensing in biological and low-temperature condensed-matter systems. In addition, the potential of defect centres in diamond for building efficient light-matter interfaces for carrying out quantum-photonics experiments is explored. The diamond laboratory uses a confocal microscope setup combined with an atomic force microscope (AFM) to perform simultaneous analysis of optical properties and size of nano-diamonds. This setup has allowed important studies on fluorescence properties of nano-diamonds over a large range of particle sizes down to the few-nm scale.

With Dr Volz arriving as a new CI at the beginning of 2013, new capabilities have been added to the nano-diamond lab. The lab now houses a closed-cycle cryostat from Montana Instruments for building a low-temperature confocal setup combined with low-temperature AFM capabilities. Besides performing low-temperature spectroscopy on defect centres in diamond, this will also allow the group to build a setup for low-temperature magnetic sensing with

diamond. In order to push the efforts on light-matter interfaces in diamond, the group has installed a system for fabricating mirrors at the end of fibre tips. In addition, a home-built low-temperature fibre-cavity microscope setup will enable cutting-edge cavity-QED experiments, not only with diamond defect centres, but also with other emitters such as low-dimensional semiconductor nanostructures.

Dr Carlo Bradac and Dr Nitin Nand in the Diamond Nanoscience Laboratory

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Dr Jean-Loup Smirr with open fridge The SSCDL laboratory


The QIRON Laboratory Macquarie University

The QIRON (Quantum Interactions with Nanoparticles) laboratory is based at Macquarie University. The aim of the lab is to study and control the properties of the smallest structures that can be fabricated to date. In particular, we are interested in controlling the quantum properties of metallic structures. The fabrication capabilities that exist nowadays allow for realization of a diversity of geometries on the nanoscale, i.e. structures with features with sizes in one part in a million of a millimeter. These particles can confine an electron gas (plasma) in a very small volume, which can then couple very strongly with optical fields forming so called plasmons. In our laboratory we combine the techniques of quantum optics and nanooptics in order to discover new physical phenomena at those scales. In the lab we prepare quantum sources of light to interact with very small particles and structures (of the order of one part in one million of a millimeter, i.e. the nanometer). Our quantum sources of light emit optical radiation in a very special state. We take the smallest amount of light that Nature allows, the photon, and engineer states of light with just a few photons

INFRASTRUCTURE

which are strongly correlated in their properties: timing, colour, direction, etc. These correlations are much stronger than any classical source of light, like a laser or a bulb, can produce. We use these properties to control and measure with a much higher precision our small structures. The lab is equipped with a set of tools which allow us to control the properties of light in a very precise manner. We can control the angular

momentum of the light (the amount of torque that light can transfer to material particles) with spatial light modulators, we have laser sources capable of producing very short pulses of light (around 100 femtosecond) and also very stable continuous wave lasers with very small bandwidths. This year we have expanded our lab facilities and open a new laboratory and a new optical table where we will continue to progress the EQuS vision.

The beauty of engineering quantum sources (credit A. Buese)

The Quantum Nanoscience Laboratory The University of Sydney

The Quantum Nanoscience Laboratory offers extensive measurement capability combining ultra-low temperatures (3 dilution fridges with based temperatures below 10 milliKelvin) with a suite of radio and microwave frequency electronics and test equipment. Two nuclear magnetic resonance spectrometers

The Quantum Nanoscience Laboratory at The University of Sydney

and an electron spin resonance system unpin work on nanoparticle MRI sensors. These facilities enable a range of nanoscale quantum systems to be investigated at low temperature, high magnetic field, and on short timescales, where exotic quantum phenomena become apparent.


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The Frequency and Quantum Metrology Laboratory The University of Western Australia

The Frequency and Quantum Metrology Laboratory, run by CI Michael Tobar, has a long history of research in precision measurement, materials characterisation, ultra-high Q-factor resonators, and the development of frequency stable, low phase noise instruments with world-class precision and performance. One such device, the Cryogenic Sapphire Oscillator, is now found in metrological laboratories around the globe, and has allowed atomic fountain clock technology to reach its ultimate performance, as well as being used in some of the most precise tests of fundamental physics ever performed. The group’s research has also led to a number of practical technologies that have been successfully patented and

commercialised. The lab offers access to three 4 K pulse-tube cryogenic systems, one 30 K system, and a BlueFors cryogen-free dilution refrigerator capable of reaching 10 mK. The lab is also well equipped with many sophisticated microwave diagnostic technologies such network analysers, synthesizers, and spectrum

analysers from RF to millimetre wave frequencies. The laboratory possesses a hydrogen maser which is distributed as a frequency reference in addition to several Cryogenic Sapphire Oscillators developed in-house that allow microwave signals to be synthesized with frequency stability of better than 1 part in 1000 trillion.

The Quantum Control LaboratoryThe University of Sydney

The Quantum Control Laboratory (QCL) was formed in 2010 with the appointment of Assoc. Prof. Biercuk to a continuing faculty position at the University of Sydney. In the short time that he has been in Australia, Assoc. Prof. Biercuk has established a world-leading research effort on quantum control and quantum simulation with trapped ions, driving major efforts towards EQuS Grand Challenges.

The research undertaken in the QCL is focused on the development of practically useful techniques in

The Frequency and Quantum Metrology Laboratory

quantum control likely to underpin the functionality of an entire generation of engineered quantum systems. Our research combines theory and experiment and leverages major international funding streams, and international collaborations facilitated via the group’s role within EQuS.

The Centre of Excellence has formed a focal point for international attention on our efforts. It has drawn high quality visiting students from the US, Germany and China, helped support applications for international funding, and formed a basis for our international media profile. EQuS has been a major facilitator for our efforts, and much of the research below could not have been carried out without the QCL’s participation in the Centre.

Ion trapping apparatus in the Quantum Control Lab

New Quantum Control equipment developed in 2013 A crystal of Ytterbium ions in a RF Paul trap

26 EQuS ANNUAL REPORT 2013 explanation of photo here

Acetone residue on a GaAs AlGaAs chip. Courtesy of PhD student James Colless (EQuS photo competition).



EQuS RESEARCH PROGRAMS

Delivering on Grand Challenges

Our Centre is organised around carefully crafted research programs and individual projects.

EQuS RESEARCH THEMES

Synthetic Quantum Systems and

SimulationApplied Theory Fundamental Theory

UQ USYD MQ UWA UNSW

Spins in Solids

Quantum Photonics

Trapped Atoms

Opto/Nano Mechanics

Superconducting Circuits

Hybrid & Integrated Systems

Cross-Disciplinary Collaboration

Quantum-Enabled Sensors and

Metrology

Quantum Measurement and

Control

Quantum Measurement and Control addresses scientific challenges in quantum limited measurement and control, to enable demonstrations of quantum solutions for control engineered problems in each technology platform.

Quantum-Enabled Sensors and Metrology delivers unprecedented levels of sensitivity and precision in applications of quantum systems for sensing, biomedical imaging and metrology.

Synthetic Quantum Systems and Simulation produces novel states of light and matter exhibiting strong quantum mechanical correlations that enable simulations of complex interacting quantum systems.

ARC Centre of Excellence for Engineered Quantum Systems



Quantum Measurement and Control

– Realise new capabilities through the development of a comprehensive and flexible quantum control toolkit. Specific example: Preserve quantum states against decoherence indefinitely using optimised quantum control, quantum feedback, open-loop protocols, weak measurement and projective measurement.

– Realise new and otherwise inaccessible regimes of physics through the construction of hybrid quantum systems. Specific example: Achieve macroscopic mechanical entanglement to test the interplay between quantum mechanics and general relativity.

– Develop design principles for robust control of hybrid quantum systems and demonstrate their utility in experimental applications.

Quantum-Enabled Sensors and Metrology

– Realise sub-cellular, in vivo, imaging in real time with microsecond time-resolution using biocompatible nano-particles and spin manipulation.

– Use quantum mechanical coherence to produce enhanced sensing technologies with unrivalled performance. Specific example: Use nanoscale diamonds as ultra-sensitive probes of magnetic fields in industrial and biological environments.

– Achieve new field and force sensing regimes using arrays of quantum controlled mechanical oscillators. Specific example: Characterize the structure of an uncrystallisable protein using single-molecule MRI with integrated cavity optomechanics.

Synthetic Quantum Systems and Simulation

– Produce programmable quantum simulators capable of outperforming the best classical technology. Specific example: Simulate quantum chemistry using conditional linear optics and photosynthesis using electromechanical systems.

– Achieve complete control over individual quantum particles in a strongly interacting many-body system with tunable interactions. Specific example: Engineer synthetic quantum system with controllable topological order.

– Address key fundamental theoretical questions. For example: When can one quantum system simulate another? How can one know that a quantum simulation is correct, or even quantum?

All of our research activities tie in to these Grand Challenges, with an aim of progressing towards them by the conclusion of the Centre.

In 2013, our research saw remarkable advances against several of our most ambitious Grand Challenges. The Centre is well positioned to exceed its extraordinary technical objectives and truly lay the groundwork for the future of quantum technology.

All of our investigators, however, share a passion for pushing the limits of quantum technology.

This is captured in our creation of The EQuS Grand Challenges that lays out our vision of some of the most important – and of course challenging – technical questions in the field.



Dr Matthew Broome working in the Quantum Technology Laboratory.


MAJOR RESEARCH PROJECTS IN 2013





Quantum Control with Trapped Ions Chief Investigator: Michael Biercuk, The University of Sydney

Researchers: Harrison Ball, Todd Green, Dr Michael Lee, Dr David Hayes, Marie Claire Jarratt, Jarrah Sastrawan, Alex Soare

Collaborators: Ken Brown, Lorenza Viola, Amir Yacoby

A major thrust of our research effort focused on the development of new quantum control protocols and techniques that allow for the error-robust control of quantum coherent systems. We have become world leaders in the development of these techniques and the incorporation of true engineering perspectives into our quantum physics research. We consider questions of robustness to perturbations, sensitivity to realistic environmental perturbations, and compatibility with large-scale systems integration. The work we have pursued through EQuS, dubbed Quantum Firmware, has led to major technical outcomes for the community and media attention in global outlets, as will be detailed in the following.

As will be demonstrated below our work on quantum control is tightly focused on the EQuS Grand Challenges and has delivered major successes both scientifically and in terms of quantitative metrics.

Engineering Transfer Functions in the Quantum Regime

Grand Challenge: Realise new capabilities through the development of a comprehensive and flexible quantum control toolkit.

EQuS research spans theory and experiment, exploiting an extraordinarily wide range of proven quantum systems for our efforts to Engineer the Quantum Future. In this section we provide highlights of major new discoveries and notable accomplishments across the Centre.

Open-loop quantum control techniques have proven themselves extraordinarily effective at suppressing the effects of environmental noise in quantum systems. Over the last few years, CI Biercuk and his team have shown that it is possible not only to suppress error using these techniques – known as dynamical error suppression – but also to accurately predict the resulting errors for complex time-dependent noise. This is a key requirement if one is to accurately bound the performance of quantum systems put to use in quantum information processing.

A major development supporting our Centre’s progress has been the realization of a robust and broadly applicable theoretical framework for understanding the effects of real noise on quantum systems. Our work has produced a detailed, and fully generic filter-design perspective for the analysis and development of quantum control techniques. Results were published in New Journal of Physics in 2013 and have already attracted multiple citations and adoption of our techniques by other groups worldwide.

A variety of methods have been developed to characterize the performance of quantum control protocols, with an eye towards

estimating error rates due to decoherence in realistic, experimentally relevant noise environments. One of the most interesting, from a practical perspective, is the concept of spectral overlap formalized by Kofman and Kurizki. In this general approach, the net susceptibility of a given quantum control protocol to environmental noise is given by the overlap in frequency between the noise power spectral density and the spectral characteristics of the modulation imparted by the control. Such insights have been particularly important for the field of dynamical error suppression (DES), which seeks to provide error robustness to quantum hardware at the physical level. These techniques address both implementation of quantum memory (dynamical decoupling) as well as nontrivial quantum logic gates as we discussed in our last progress report.

Despite broad successes in the implementation of the filter function formalism, there has remained a significant gap in our understanding of how to efficiently calculate expected operational fidelities and error rates for complex quantum control protocols and for situations in which universal (i.e. multi-axis) time-dependent noise sources are present. For instance, relatively little was known about how to




account for the accumulation of error due to pulse non-idealities in dynamical decoupling sequences; the bang-bang limit is still widely assumed in analytic treatments.

Additionally, while it was understood that spectral overlap techniques may be employed in order to evaluate error rates, it was not known how to efficiently produce analytic filter functions appropriate for such complex quantum control protocols. This is largely due to the fact that the analytic complexity of deriving such functions grows significantly as soon as non-commuting operators appear in the control Hamiltonian - as would be the case in dynamical decoupling with nonzero-duration control pulses or other nontrivial control operations.

Sydney PhD student Todd Green has addressed these major gaps in the community by developing an effective Hamiltonian formulation that can be used to treat any piecewise-constant control sequence. This work involves significant complication because of the time-varying form of the dephasing environment. He has produced a

closed-form analytic expression for the universal (three-dimensional) filter function given an arbitrary sequence with arbitrary control rotations.

In the presence of weak decohering noise, this work showed how all Cartesian contributions to the resulting operational fidelity could be calculated using noise power spectral densities along with the Fourier-space representations of the elements of the control matrix. Conditions under which high-order contributions may be ignored were laid out and validated using brute-force numerics.

As an example of the utility of this approach we study dynamical decoupling incorporating both realistic, nonzero-duration “primitive” pi-pulses and more complicated dynamically corrected gates. We are able to derive first order filter functions for the incorporation of arbitrary control pulses into a dynamical decoupling sequence and validate the performance of dynamically corrected gates in mitigating pulse errors in these sequences.

This work has very broad applicability. We now use it to characterize the performance of novel modulated/compensating gates with complex frequency, amplitude and phase profiles. Further, it may be employed in an algorithmic context. For instance, we currently apply this approach to understand and predict the performance of randomized benchmarking techniques in the presence of engineered noise.

Additionally, we showed that the analytic filter functions derived from this method were shown to provide close approximations for calculated operational fidelity (or equivalently error susceptibility) in a time of order ms on a laptop, as compared with many hours of processing on a workstation when averaging Bloch vector trajectories. Thus, our approach provides the benefit of providing a computationally efficient approach for calculating operational fidelities in the presence of complex control protocols.

The effect of noise during a driven operation – the noncommuting nature of the noise and control leads to complex dynamics.


Quantum Control with Trapped Ions (continued)



Designing a Practical, High-Fidelity Long-Time Quantum Memory

Grand Challenge: Preserve quantum states against decoherence indefinitely, using optimised quantum control, quantum feedback, open-loop protocols, weak measurement and projective measurement.

In collaboration with Prof. Lorenza Viola at Dartmouth our team has addressed the problem of designing a practically useful quantum memory through quantum control protocols, leveraging our insights into Walsh Dynamical Decoupling. Our technique provides a clear path to this EQuS grand challenge, showing how quantum states may be preserved indefinitely through quantum control techniques.

A variety of studies has consistently pointed to dynamical error suppression as a resource-efficient approach to substantially reducing physical error rates. However, they have largely focused on two control regimes: the “coherence-time” regime, where the goal is to extend the characteristic (“1/e” or T2) decay time for coherence as long as possible, and the “high-fidelity” regime, where the goal is to

suppress errors as low as possible for storage times short compared to T2 – for instance, during a single quantum gate. Still, these two regimes do not capture the typical operating conditions of any true quantum memory, namely, extremely low error probabilities (e.g. deep below the fault-tolerance threshold) maintained for arbitrarily long storage times. This would be required, for instance, in a quantum repeater or in a quantum computer where some quantum information must be maintained, while large blocks of an algorithm are carried out on other qubits.

In our work, we showed how dynamical error suppression techniques can be employed to realize a useful quantum memory capable of preserving quantum information for long times with high fidelity, while meeting the practical requirement of a small access latency. Given a variety of technical considerations, we identified the periodic repetition of a high-order dynamical decoupling sequence as an effective strategy for memory applications, and analytically characterized the resulting long-time coherence.

Remarkably, our study revealed that the error in a quantum memory at long times may be rigorously bounded using asymptotic expressions. We identified conditions under which a “coherence plateau” could be engineered, and qubit fidelity guaranteed to a desired level at long storage times – even in the presence of pulse imperfections, realistic noise environments and other practical constraints. The results suggested, for instance, that quantum states could be preserved with error probabilities in the range 10-9 for hours using trapped ion qubits. In certain conditions, we even showed that it would be possible to maintain this error level indefinitely.

This research was published in 2013 in the journal Nature Communications, and garnered significant international media attention. The work was highlighted in The New York Times, Forbes, and Wired magazines among others. This extraordinary interest from major media outlets highlights the public and commercial appeal of EQuS research.

The effect of periodic repetition on dynamical decoupling pulse sequence spectral response.



Robust Quantum Control for Nontrivial Quantum Logic

Grand Challenge: Develop design principles for robust control of hybrid quantum systems and demonstrate their utility in experimental applications.

A major challenge in quantum hardware is developing methods to implement quantum operations that are robust against error – especially the ubiquitous phenomenon of decoherence. Our group has contributed to a broad area of work on this topic, developing techniques using open-loop control in order to build-in robustness against external perturbations.

Building on the filter-design methodology described above, we have produced the first independent performance validation of dynamically corrected gates – quantum logic operations believed to be robust against errors – in the presence of time-dependent noise. These protocols allow important quantum logic operations to be implemented in the presence of both control imperfections and environmental noise with reduced probability of error. We have produced full expressions for the filter function to the first order in the Magnus expansion for previously published DCG constructions, accounting for the dephasing and depolarization effects of a nominally pure dephasing environment during application of a nontrivial control operation.

With this work, we now understand how to evaluate the efficacy of DCG constructions in the presence of classical noise and have verified that similar to the filter-function treatment of dynamical decoupling (DD), it is possible to reduce operational error rates by several orders of magnitude by use of DCGs. This is a significant result demonstrating a path towards error-robust control of quantum systems in real environments.

The capability to calculate filter functions for DCGs motivated our work to address a specific challenge pertaining to the development of robust control protocols most compatible with the classical hardware required to control

complex engineered quantum systems. As described above, previously our group studied the problem of reducing sequencing complexity in dynamical error suppression for the implementation of the quantum memory using Walsh functions. With this background, we have shown that the Walsh functions provide efficient performance against control complexity and the supporting sequencing hardware for nontrivial logic, as well as memory.

We may determine Walsh modulation protocols for arbitrary quantum control that provide protection against unwanted environmental fluctuations and control imperfections (e.g. master oscillator noise). We explore DCG performance using a filter-design framework in which the error suppressing properties of a quantum gate are captured in the form of an easily calculable filter function.

Our new Walsh DCGs are constructed from always-on, piecewise constant, and continuous control fields with amplitudes determined via Walsh synthesis. Through numerical optimization of the filter function we have identified a general family of first order DCGs executing arbitrary rotation angles. We also explore this analytically in order to derive the underlying decoupling condition responsible for the cancellation of the first order terms in a Taylor expansion of the filter function roll-off. By including higher-order Walsh functions in the spectral synthesis, we extend this procedure to the generation of higher-order DCGs and find regions of robustness of construction against fluctuations in Walsh amplitudes. Our analytic and numerical insights now show a path forward for the generalization of dynamical protection to the kinds of arbitrary rotation angles required, for instance, in an implementation of Shor’s algorithm, without a sacrifice of hardware compatibility.

We have also provided the first insights into the performance of composite-pulse sequences. These protocols, as developed in NMR, have been designed and traditionally employed to mitigate the effect of static control errors arising in pulse implementation. In particular,

well-known sequences such as SK1 and BB1 are intended to cancel (to the first and second order, respectively) pulse-length errors, whereas so-called CORPSE is intended to compensate for off-resonance (or detuning) errors.

We have engaged in a new collaboration between EQuS researchers, and the groups of Prof. Ken Brown at Georgia to study the robustness of composite-pulse sequences against time-dependent control noise, fundamentally leveraging our new filter function formalism. Remarkably, in all cases robustness to control noise up to frequencies as high as 10% of the Rabi frequency are observed, significantly expanding the practical usefulness of such sequences in engineered quantum systems functioning within realistic noise environments.

Experimental Quantum Logic and Noise Filtering Using Trapped Ions


The development of engineered quantum systems requires major investment in classical control hardware allowing experimentalists to access and manipulate quantum coherent effects of interest. In this part of our program we have focused on the development of a platform to test AC-based quantum control protocols using Ytterbium ions in a Paul trap. This is a new experimental system that came online this year with first light from trapped ions in January 2013. The group made extremely rapid progress with our first coherent control demonstrations coming just weeks later. Our advances this year take the form of major developments in our microwave system, demonstrations of high-fidelity coherent control, and substantive validation of our entire filter transfer function formalism.

Under this program, we have assembled a precision quantum control system that is now being replicated in Yb-ion-trapping labs around the world for the 12.6GHz microwave qubit in Yb+ ions. We realized that high fidelity


Quantum Control with Trapped Ions (continued)



control requires an extremely stable local oscillator, as qubit coherence in clock transitions is generally limited by master oscillator quality, rather than extrinsic factors such as magnetic field fluctuations. We utilize a LO phase reference at 10 MHz provided by a Cs clock followed by an ultra-low-phase-noise Wenzel crystal oscillator. This phase reference drives an ultra-low-phase-noise vector signal generator achieving phase noise (carried 12.6 GHz) below -80 dBc at 100 Hz offset and -50 dBc at 1 Hz, while also providing extraordinary long-term stability. This VSG is followed by a low-phase-noise microwave power amplifier (phase is not generally considered in the architecture of a power amp or LNA) and lensed microwave horn mounted on a rotating stage to maximize coupling of the linear polarization to the qubit.

The phase stability of the LO has permitted record-setting direct measurements of qubit coherence via Ramsey interference combined with extraordinary modulation techniques. Previous experiments have been limited to coherence times of several hundred milliseconds, due largely to the poor phase stability of their high-power microwave source. We have extended this approximately 10x to a direct Ramsey FID time of ~3 seconds and a spin echo decay of over 6s.

The fidelity of single-qubit control operations has been characterized using randomized benchmarking. We have measured operational infidelities of approximately 6e-5, a record for this qubit (~100x better than previous Yb ion experiments), and approaching published record levels for any qubit. At this stage we believe our measured operational fidelity remains limited by both minor inhomogeneities over the trap volume and small drifts in microwave power over very long experiments with up to 10,000 computational gates (sometimes extending overnight).

A significant capability provided by our ion-trap quantum control system is the ability to use the internal IQ modulation capabilities of our vector signal generator to engineer the path experienced by the qubit . We may thus use our trapped ions as a model quantum system capable of providing insights into the performance of alternate qubit technologies.

We implement this capability in our system by numerically generating a time-domain IQ modulation protocol (both dephasing and depolarization noise engineering, is possible but we restrict the current discussion exclusively to dephasing noise) whose two-time correlation function produces

a given power spectral density when Fourier transformed. Noise is injected with user-defined amplitude on top of any IQ modulation designed to implement a particular gate and spectral characteristics varied in accordance with desired physical regimes.

We have now tested primitive NOT pulses and DCGs using engineered noise in a regime where error rates at the percent level dramatically exceed the natural baseline error rates for control pulses. We have, for the first time, demonstrated regimes of noise where DCGs outperform primitive pulses for both NOT operations and pi/2 pulses.

In these experiments, we are able to compare experimental measurements with full numerical integration of the Schroedinger equation, finding excellent agreement between data and theory. In addition, we find good agreement with the first-order filter function formalism up to limits imposed by the first-order approximation. Breakdown of this approximation occurs where predicted analytically, forming a major experimental validation of our generalised noise filtering framework. Further, our experiments validate the Walsh-modulated error-suppressing gates described above.



Semiconductor Quantum DotsChief Investigators: David Reilly, Andrew Doherty & Stephen Bartlett, The University of Sydney; Tom Stace, The University of Queensland

Partner Investigator: Professor Charlie Marcus, Niels Bohr Institute, The University of Copenhagen

Researchers: John Hornibrook, Xanthe Croot, James Colless, Alice Mahoney, Sebastian Pauka, Matthew Wardrop.

Grand Challenge: Demonstrate low noise microwave tools for quantum limited actuation and stabilize and program nuclear spin gradient fields using fast realtime feedback

EQuS research on solid-state quantum devices includes a major effort on semiconductor-based quantum

systems called quantum dots. These devices allow experimentalists to confine, manipulate, and probe individual electrons in a solid material and engineer exotic states of quantum matter. This effort is led from the Quantum Nanoscience Laboratory (QNL), Directed by CI Reilly at The University of Sydney.

In 2013, we extended our recently developed technique of dispersive gate sensing (J I Colless et al, Phys Rev Lett, 2013) to multichannel readout using multiplexing techniques. These results have been accepted for publication in Applied Physics Letters.

Six quantum dot device, with integrated charge sensors.




In the past year, we have also ramped up our efforts to develop “quantum –hardware” – the much needed electronic systems that control quantum devices. In collaboration with Microsoft Corp (Redmond), we have developed a suite of cryogenic electronics for fast control of spin qubits. Three publications and one patent are in preparation.

Quantum Hardware

Controlling and measuring quantum systems requires custom engineering solutions, with no available commercial, off the shelf devices. The Quantum Nanoscience Laboratory at Sydney is developing cryogenic electronics and interconnect solutions for this purpose.

(a) Optical micrograph of a 10:1 MUX chip with integrated bias tees.

(b) Frequency response of the MUX chip with inductors Li each connected to GaAs HEMT with a gate-controllable conductance to mimic the response of 10 QPCs. Data shows the response with all HEMTs in the resistive state (black), odd HEMTs resistive (blue) and even HEMTs resistive (red). (c) Shows an optical micrograph of a section of the HEMT device with dashed lines indicative of bond-wires.

Quantum Hardware: controlling and measuring quantum systems requires custom engineering solutions, not available as commercial, off the shelf devices. The Quantum Nanoscience Laboratory at Sydney is developing cryogenic electronics and interconnect solutions for this purpose.



Exploiting Phonons in Semiconductor Quantum Devices

Chief Investigators: David Reilly & Andrew Doherty, The University of Sydney; Tom Stace, The University of Queensland

Researchers: James Colless, Xanthe Croot

Collaborators: Sean Barrett (deceased), Jing Lu, Arthur Gossard

Grand Challenge: Realise new and otherwise inaccessible regimes of physics through the construction of hybrid quantum systems

In 2013, this research program produced two significant publications [Stimulated Phonon Emission in a Driven Double Quantum Dot JI Colless, XG Croot, TM Stace, AC Doherty, SD Barrett, H Lu, AC Gossard, DJ Reilly arXiv preprint arXiv:1305.5982. Submitted to Nature Nanotechnology,and Dynamical Steady States in Driven Quantum Systems TM Stace, AC Doherty, and DJ Reilly Physical Review Letters 111, 180602 (2013)] that examine the interaction

of phonons and single electrons in semiconductor quantum dots. These results highlight the role of the phononic environment in understanding the driven dynamics of coherent quantum systems and provide a path for transducing quantum information between photons, phonons, spins and charge. The work is a strong collaboration between theorists CI Tom Stace (UQ) and CI Andrew Doherty (Sydney) and the experimental team of CI Reilly’s laboratory (Sydney). Building on this foundation, new work is underway to construct microwave circulators (devices needed in many quantum science experiments) from quantum Hall systems.

(a) Cartoon of the double dot potential showing a single electron wave function coherently tunnelling between the ground Ig⟩ and excited state |e⟩ under microwave excitation. In a microwave analog of the Raman effect, photon-stimulated emission of phonons (ripples) is modulated by the mode spectrum set by the intra-dot spacing, which for our device ~ 280 nm.

(b) Energy-level diagram for the single-electron charge qubit showing the stimulated phonon emission process (light blue) that leads to asymmetric line shapes and population inversion. At a later time, spontaneous emission of a phonon (orange) leads to qubit relaxation. Grey shading depicts virtual states.

(c) Micrograph of the double dot device showing surface gates and ohmic contacts to the electron gas (crossed squares). Microwaves are applied to the plunger (P) or centre (C) gate. The conductance GQPC of a proximal rf-QPC detects the average charge state of the dot and modulates the amount of reflected rf power Prf from a resonant tank-circuit, enabling fast readout (see §Methods for details).

(d) Charge stability diagram of the double dot, detected using the rf-QPC. Labels (n,m) denote the number of electrons in the left and right quantum dots respectively. The demodulated signal Vrf is proportional to the QPC conductance and thus the double dot charge configuration. Gate voltages VL and VR are applied to gates L and R in (c). Red arrows indicate the direction of allowed transitions under resonant microwave excitation.

Semiconductor Quantum Dots (continued)




Non-Markovian Dynamics in Driven Quantum Systems

Chief Investigator: Tom Stace, The University of Queensland

Researchers: Sahar Basiri Esfahani, Andrew Bolt, Bixuan Fan, Clemens Mueller


Semiconducting quantum dot systems, which behave as exquisitely tuneable artificial atoms, are typically measured using quantum point contacts, or single electron transistors. These respond to the electronic configuration on the quantum dot, yielding information about its quantum state, and can also be used as spin-sensitive detectors for even a single electron. Thus, they are simultaneously some of the most sensitive electrometers and magnetometers available.

Quantum dots couple very strongly to their external environment, both electromagnetic and vibrational. It follows that measurements of the electronic state of the quantum dot indirectly reveals information about its environment, and if used judiciously, to control the environment. There is then a question of how to describe the interplay of measurement of the quantum dot, which tends to localise its quantum state and the effects of external fields, which tend to drive dynamical changes.

In recent experiments from the Reilly group (in review), measurements of microwave-driven quantum dots demonstrated a range of phenomena that are inconsistent with a number of common approximations that are used to understand theoretical models of such systems. Instead, these results highlight the subtle interplay between dynamics and measurement in quantum systems.

Understanding these results has required theoretical developments to describe quantum systems that exist in a regime where the effects of dynamics, measurement and the environment may all be of comparable magnitude (Stace, Doherty and Reilly, Phys Rev Lett 111, 180602, 2013). This new theoretical understanding will become important in order to develop increasingly precise measurement and control of such systems.

Microwave Amplifiers for Semiconductor Quantum Devices

Chief Investigators: David Reilly, The University of Sydney; Michael Tobar, The University of Western Australia

Researchers: Romain Bara-Maillet, James Colless,Torsten Gaebel


In collaboration with CI Tobar, the Quantum Nanoscience Laboratory has continued to design and construct a new kind of cryogenic microwave amplifier that can boost quantum signals in a variety of systems being investigated in EQuS. Tobar and Reilly won travel funding in 2013, to continue this wor

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ANNUAL REPORT 2013equs.org/sites/default/files/documents/eQusAnnualReport2013web3.… · PUBLICATIONS 103 – Journal Articles 104 APPENDIX 2 CONFERENCES 107 Unpublished Presentations