Superconducting Quantum Processors: Status and Outlook

Doug McClureIBM Research

ETSI-IQC WorkshopNovember 6, 2019

The road to quantum advantage

2016 ~2020s1960s 2050+

Quantum Science

Quantum Ready

Quantum Advantage

Created the fundamental theoretical and physical building blocks of quantum computing.

Engage the world and prepare for the quantum computing era.

Beneficial to use a quantum computer to solve real-world problems.

Physical qubit systems

Topological systems?

Atomic systems Electron spins

Image: http://vandersypenlab.tudelft.nl/

Image: http://www.quantumoptics.at/

Image: http://topocondmat.org/ w2_majorana/braiding.html

Majorana fermions

Superconducting circuits

• Straightforward wafer-scale fabrication with established materials and processes

• Accurate device design with standard software

• Scalable architecture with circuit QED paradigm

• Control and readout using readily available components

Photons

Image: PSIQuantum

Superconducting Microwave Resonators: read-out of qubit states multi-qubit quantum bus noise filter

Superconducting Transmon Qubits:

Superconducting quantum processor building blocks

100 nmX 100 nm

Josephson Junction acts as a non-linear inductor, allowing isolation of lowest two allowed energy levels

Phys. Rev. A 76, 04319 (2007)

Superconducting qubit environment, control, and readout

• Cryo temperatures required Qubits sit at base of dilution refrigerator

• Control and readout performed by sending pulses over coaxial cables

• Input lines use attenuation to reduce incoming noise

• Output lines use cryogenic amplification and isolation

Superconducting qubit performance

• Coherence times Steady increase over 20 years Now 100’s of microseconds

• Single-qubit gate errors < 0.1%, not a limiting factor

• Two-qubit gate errors < 1% demonstrated with cross-resonance gate used at

IBM Near threshold for error correction

• Readout errors Less than 1% with use of quantum-limited amplifiers

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Quantum processor performance

• System-level benchmarks will be key for comparing the “power” of different quantum processors Affected by device features not captured by lower-level properties Results depend on how the problem is mapped onto the device

System Benchmarks

• Entangled state fidelities• Algorithm results• Designed system-level

benchmarking routines, e.g. quantum volume

Device Properties

• Number of qubits• Connectivity map• Crosstalk matrix• Max. shot rate

Operation Fidelities

• Single-qubit gates• Multi-qubit gates• Simultaneous gates

(single and/or multi-Q)• Readout• Initialization

Qubit Parameters

• Physics of operation• Control and readout

frequencies• Coherence time• Temperature

IBM Q Experience

Launched May 4, 2016

Free, cloud-based GUI and programmatic access to small quantum devices and simulators

Detailed user guide with example algorithms

> 160,000 users

> 15 million experiments

> 200 scientific papers

New in 2019: cloud-hosted programming in Qiskit

The elements of Qiskit

• Build and run circuits

• Study and mitigate errors

• Simulate device behavior

• Solve real-world problems

Terra

Aqua

Aer

Ignis

Open Source (Apache 2.0)

Written in Python 3

Modular and extendible

qiskit.org

Putting quantum computers in the hands of quantum information theorists, software developers and end-users

IBM Q cloud systemsYorktown Heights, NY: 3x 20Q, 1x 14Q, 4x 5Q

Poughkeepsie, NY: 2x 20Q, 3x 5Q, 1x 53Q

Devices are named after various cities, but located in one of the two sites above

Rochester

7 with free public access

Toward practical use cases

• Quantum volume, our system-level benchmark, doubling every year Represents effective size of usable quantum state space

• IBM Q Network: studying applications in chemistry, finance, optimization, etc. Qiskit provides path to test ideas on real hardware and track improvements on problems

of interest

• Enabling quantum error correction Reduce errors well below threshold to minimize overhead

Improve scalability to support need for many qubits

Research more efficient QEC codes

Summary and outlook• Programmable superconducting quantum processors

are now accessible over the cloud

• Continued improvements in coherence times and error rates

• Increasing efforts underway toward early use cases, quantum advantage, and demonstration of QEC