IMPACT OF NOISE ON FIBER OPTIC QUANTUM KEY … · 2016-11-01 · system using optsim software The term Wavelength-Division Multiplexing is commonly applied to an optical carrier (which

IMPACT OF NOISE ON FIBER OPTIC

QUANTUM KEY DISTRIBUTION SYSTEM

A PROJECT REPORT

Submitted by

S.KANNADHASAN

Register No: 14MCO013

in partial fulfillment for the award of the degree

of

MASTER OF ENGINEERING

in

COMMUNICATION SYSTEMS

Department of Electronics and Communication Engineering

KUMARAGURU COLLEGE OF TECHNOLOGY

(An autonomous institution affiliated to Anna University, Chennai)

COIMBATORE - 641049

ANNA UNIVERSITY: CHENNAI 600 025

APRIL - 2016

ii

BONAFIDE CERTIFICATE

Certified that this project report titled “IMPACT OF NOISE ON FIBER OPTIC

QUANTUM KEY DISTRIBUTION SYSTEM” is the bonafide work of

S.KANNADHASAN [Reg. No. 14MCO013] who carried out the research under my

supervision. Certified further, that to the best of my knowledge the work reported herein

does not form part of any other project or dissertation on the basis of which a degree or

award was conferred on an earlier occasion on this or any other candidate.

HHHH

The Candidate with Register No.14MCO013 was examined by us in the project

viva –voice examination held on ............................

INTERNAL EXAMINER EXTERNAL EXAMINER

SIGNATURE

Ms.S.KRITHIKA

PROJECT SUPERVISOR

Department of ECE

Kumaraguru College of Technology

Coimbatore-641 049

SIGNATURE

Dr.A. VASUKI

HEAD OF THE DEPARTMENT

Department of ECE

Kumaraguru College of Technology

Coimbatore-641 049

iii

ACKNOWLEDGEMENT

First, I would like to express my praise and gratitude to the Lord, who has

showered his grace and blessings enabling me to complete this project in an excellent

manner.

I express my sincere thanks to the management of Kumaraguru College of

Technology and Joint Correspondent Shri Shankar Vanavarayar for his kind

support and for providing necessary facilities to carry out the work.

I would like to express my sincere thanks to our beloved Principal

Dr.R.S.Kumar Ph.D., Kumaraguru College of Technology, who encouraged me

with his valuable thoughts.

I would like to thank Dr.A.Vasuki Ph.D., Head of the Department, Electronics

and Communication Engineering, for her kind support and for providing necessary

facilities to carry out the project work.

In particular, I wish to thank with everlasting gratitude to the project

coordinator Dr.M.Alagumeenaakshi Ph.D., Assistant Professor III, Department of

Electronics and Communication Engineering, throughout the course of this project

work.

I am greatly privileged to express my heartfelt thanks to my project guide,

Ms.S.Krithika M.E., Assistant professor, Department of Electronics and

Communication Engineering, for her expert counselling and guidance to make this

project to a great deal of success.

I wish to convey my deep sense of gratitude to all teaching and non-teaching

staff of ECE Department for their help and cooperation.

Finally, I thank my parents and my family members for giving me the moral

support and abundant blessings in all of my activities and my dear friends who helped

me to endure my difficult times with their unfailing support and warm wishes.

iv

ABSTRACT

This project is to observe the impact of noise generated from fiber optic system

using Quantum Key Distribution .Quantum Key Distribution is the important process for

this information or data transmission .Its highly secure, Quantum Key Distribution

performed continuously, No one can hack between two user (Alice and Bob).the output

result shows that how can measured the impact of noise from encryption algorithm in

fiber optic system using Quantum Key Distribution. Now we simulate basic Quantum

Key Distribution (QKD), Noise immune systems, single data telecom channel

transmission process, Wavelength Division Multiplexing, Dense Wavelength Division

Multiplexing and Co-Counter propagating. Fundamental concept for this process is given

electrical generation and laser source combined and its convert optical energy to measure

the power amplitude ,best sampling rate, distortion, error sampling using eye diagram and

spectrum analyzer. The impact of the noise on fiber optics Quantum Key Distribution

system using optsim software

The term Wavelength-Division Multiplexing is commonly applied to an optical

carrier (which is typically described by its wavelength), whereas frequency-division

multiplexing typically applies to a radio carrier (which is more often described by

frequency). Since wavelength and frequency are tied together through a simple directly

inverse relationship, in which the product of frequency and wavelength equals c (the

propagation speed of light), the two terms actually describe the same concept.

Quantum Cryptography (QC) uses quantum channel to exchange key securely and

keeps unwanted parties or eavesdroppers from learning sensitive information. A

technique called Quantum Key Distribution (QKD) is used to share random secret key by

encoding the information in quantum states. Photons are the quantum material used for

encoding. QKD provides an unique way of sharing random sequence of bits between

users with a level of security not attainable with any other classical cryptographic

methods.

TABLE OF CONTENTS

CHAPTER.NO. TITLE PAGE NO.

ABSTRACT iv

LIST OF FIGURE vii

LIST OF ABBREVATIONS ix

1 INTRODUCTION 1

1.1 QUANTUM CRYPTOGRAPHY 1

1.2 QUANTUM KEY DISTRIBUTION 2

1.3 THEORMS OF QKD 3

1.3.1 HEISENBERG’S UNCERTAINTY

PRINCIPLE

3

1.3.2 QUANTUM ENTANGLEMENT 3

1.3.3 QUANTUM NO-CLONING 5

1.3.4 PHOTON POLARISATION 5

1.4 KEY DISTRIBUTION 7

1.5 METHODOLOGY 8

1.6 SPONTANEOUS RAMAN

SCATTERING GENERATED BY

SINGLE TELECOM DATA CHANNEL

10

2 LITERATURE SURVEY 12

3 OPTSIM SOFTWARE ANALYZE 20

3.1 INTRODUCTION 20

3.2 OPTSIM 5.2 20

4 NOISE IMMUNE SYSTEM 25

4.1 QKD SETUP 25

4.2 NOISE IMMUNE QKD 26

5 SINGLE DATA TELECOM CHANNEL 28

5.1 INTRODUCTION 28

5.2 IMPLEMENTATION OF SINGLE

DATA TELECOM CHANNEL

29

5.3 WAVELENGTH DIVISION

MULTIPLEXING

30

5.4 DENSE WAVELENGTH DIVISION

MULTIPLEXING

31

5.5 CO-COUNTER PROPAGATING USING

SAMPLE MODE

32

6 SIMULATION RESULT 34

6.1QKD SETUP 34

6.2NOISE IMMUNE QKD 34

6.3 IMPLEMENTATION OF SINGLE DATA

TELECOMMUNICATION CHANNEL

35

6.4 WAVELENGTH DIVISION

MULTIPLEXING

36

6.5 DENSE WAVELENGTH DIVISION

MULTIPLEXING

38

6.6 CO-COUNTER PROPAGATING USING

SAMPLE MODE

39

7 CONCLUSION AND FUTURE WORK 43

REFERENCES 44

LIST OF PUBLICATIONS 47

vii

LIST OF FIGURES

FIGURE.NO.

FIGURE NAME

PAGE NO.

1.1 QUANTUM CRYPTOSYSTEM 1

1.2 QUANTUM KEY DISTRIBUTION 2

1.3 UNCERTAINTY PRINCIPLE 3

1.4 QUANTUM ENTANGLEMENT 4

1.5 QUANTUM NO CLONING 5

1.6 PHOTON POLARIZATION 6

1.7 PHOTON POLARIZATION DIRECTION 7

1.8 FLOWCHART OF QKD PROTOCOL 8

1.9 KEY EXCHANGE 9

1.10 EVOLUATION OF THE SRS GENERATED BY A

SINGLE TELECOM DATA CHANNEL

10

4.1 IMPLEMENTATION OF QKD 25

4.2 NOISE IMMUNE QKD 26

5.1 BASIC BLOCK DIAGRAM OF SINGLE DATA

TELECOM CHANNEL

28

5.2 IMPLEMENTATION OF SINGLE CHANNEL 29

5.3 WAVELENGTH DIVISION MULTIPLEXING 30

5.4 DENSE WAVELENGTH DIVISION MULTIPLEXING 31

5.5 CO-COUNTER PROPAGATING 33

6.1 INPUT SPECTRUM OF QKD 34

6.2 OUTPUT SPECTRUM OF QKD 34

6.3 SPECTRUM BEFORE NOISE IMMUNE 34

6.4 SPECTRUM AFTER NOISE IMMUNE 35

viii

6.5 SPECTRUM NOISE INPUT 35

6.6 SPECTRUM NOISE OUTPUT 36

6.7 EYE DIAGRAM FOR SINGLE DATA CHANNEL 36



6.10 EYE DIAGRAM FOR WAVELENGTH DIVISION

MULTIPLEXING

37



6.13 EYE DIAGRAM FOR DENSE WAVELENGTH

DIVISION MULTIPLEXING

39



6.16 QUALITY FACTOR VALUE FOR 130 KM 40

6.17 EYE DIAGRAM FOR 100KM 41


6.19 QUALITY FACTOR VALUE FOR 100KM

42

6.20 EYE DIAGRAM FOR CO-COUNTER

PROPAGATING 13OKM

42

ix

ix

LIST OF ABBREVIATIONS

QC Quantum Cryptography

QKD Quantum Key Distribution

QM Quantum Mechanics

SRS Spontaneous Raman Scattering

FBG Fiber Bragg Gratings

FWHM Full-Width Half-Maximum

NP Non Polynomial

TDM Time Division Multiplexing

QPSK Quadrature Phase Shift Keying

BER Bit Error Rate

OSNR Optical Signal to Noise Ratio

PBS Polarization Beam Splitter

PD Photo Diode

PMD Polarization Mode Dispersion

WDM Wavelength Division Multiplexing

DWDM Dense Wavelength Division Multiplexing

DOP Degree of Polarization

DGD Differential Group Delay

DOS Denial of Service

OFDM Orthogonal Frequency Division Multiplexing

x

TTP Trusted Third Party

AMZI Asymmetric Mach-Zehnder Interferometer

PKI Public Key Infrastructure

PR Polarisation Rotators

APD Avalanche Photo Diodes

PON Passive Optical Network

SMZ Symmetrical Mach-Zehnder

TDM Time Division Multiplexing

WDM Wavelength Division Multiplexing

SMF Single Mode Fiber

CW Continuous wave

SPD Single photon detector

OOK On Off Key

RZ Return To Zero

1

CHAPTER 1

INTRODUCTION

1.1 QUANTUM CRYPTOGRAPHY

Quantum Cryptography [5] is a relatively recent arrival in the information security

world. It harnesses the laws of Quantum Mechanics (QM) to create new cryptographic

primitives. Quantum Key Distribution (QKD) is one quantum cryptographic primitive

which is achievable with today’s technology. Secure key distribution is one of the

interesting research in the network security field. Digital cryptography affords a solution

based on computational security. As today’s rapid technology growth is capable of

breaking the security by a simple technique called brute force attack in near future.

Furthermore the imminent product from quantum mechanics principle is the quantum

computer and its algorithms are capable of solving the Non Polynomial (NP) problem in

polynomial time. On the other hand, quantum cryptography from QM offers an

unconditional security by its uncertainty principle, no-cloning theorem and entanglement.

Fig 1.1 Quantum Cryptosystem

2

1.2 QUANTUM KEY DISTRIBUTION

The most well known and developed application of quantum cryptography is

Quantum Key Distribution (QKD), which is the process of using quantum

communication to establish a shared key between two parties (Alice and Bob) without a

third party (Eve) learning anything about that key. Key distribution is achieved by Alice

encoding the bits of the key as quantum data and sending them to Bob; if Eve tries to

learn these bits, the messages will be disturbed and Alice and Bob will notice. The key is

then typically used for encrypted communication using classical techniques. For instance,

the exchanged key could be used as the seed of the same random number generator both

by Alice and Bob.

Fig 1.2 Quantum Key Distribution

Heisenberg - based protocols use the fact that measuring a quantum state changes

it: the eavesdropper will introduce errors into the information transfer along a quantum

channel which should always be detected by the protocol.

Entanglement - based protocols do not have any information to eavesdrop.

Information only springs into existence when the entangled quanta are measured. The

eavesdropper’s only potential ploy is to attempt to inject extra quanta into the protocol.

The extra quanta violate Bell’s inequalities, and so the eavesdropper will also be detected

3

in this case. Quantum no-cloning further ties the eavesdropper’s hands, as no copies of

quanta can be taken for processing later.

1.3 THEORMS OF QKD

1.3.1 HEISENBERG’S UNCERTAINTY PRINCIPLE

There is a complication to quantum observations, when the position of a quantum

is measured, be it a photon, electron or whatever, its velocity cannot be known exactly

and vice versa. This is the Heisenberg Uncertainty Principle exists to protect quantum

theory.

Fig 1.3 Uncertainty Principle

It is impossible to measure, predict or both the position and momentum,

simultaneously, of a particle, with unlimited precision in both quantities. if it was

possible, we could predict the future position of everything in the cosmos

1.3.2 QUANTUM ENTANGLEMENT

A quantum property of relevance to QKD is quantum entanglement. Pairs of

quanta can be produced which behave as if they are a single entity, so called EPR pairs

following the work of Einstein, Podolsky and Rosen[7]. For example, quanta possess a

property called “spin”: one quantum could have spin up, one spin down, so that the total

4

spin is zero but until a measurement is made it is not clear which is which of the pair. If

the pair is separated, measuring one causes the other’s wave function to collapse into the

opposite state. It appears to know instantaneously that its partner has been measured;

apparently contradicting Einstein’s finding that nothing can travel faster than light. This

is known as the EPR paradox.

Fig1.4 Quantum Entanglement

Quantum Entanglement is a physical phenomenon that occurs when quantum

systems such as photons, electrons, atoms or molecules interact and then become

separated, so that they subsequently share a common quantum mechanical state. Even

when a pair of such entangled particles are far apart, they remain "connected" in the sense

that a measurement on one of them instantly reveals the corresponding aspect of the

quantum state of its twin partner. These "aspects" of quantum state can be position,

momentum, spin, polarization, etc. While it can only be described as a superposition with

indefinite value for the entangled pair, the measurement on one of the partners produces a

definite value that instantly also determines the corresponding value of the other. The

surprising "remote connection" between the partners and their instantaneous action

"faster than light" that would seem to contradict relativity has been the reason for intense

research efforts, both theoretically and experimentally. In the corresponding experiments,

5

entanglement is proven by correlation of the measurment outcomes on the separated

twins.

1.3.3 QUANTUM NO-CLONING

Quantum No-Cloning Theorem specifically prevents copies of an unknown

quantum state from being created and was first identified by Wooters, Zurek and

Dieksp[8] . It is another ‘protection’ mechanism for quantum theory, in that copying

unknown quantum states would enable an observer to measure the copies exactly, and

avoid the restrictions of Heisenberg’s Uncertainty Principle. So, backup copies of

quantum states cannot be taken and used in quantum computing error correction routines,

and an eavesdropper cannot create copies of quantum information sent along a quantum

channel. It also means that a quantum signal cannot be amplified along a quantum

channel.

Fig 1.5 Quantum No Cloning

It is not possible to copy an unknown quantum state with perfect fidelity. Bound

on copy fidelity is such the eavesdropper will not succeed in tapping the channel even if

using the best possible quantum copying machine

1.3.4 PHOTON POLARIZATION

Electromagnetic waves such as light have an electric field associated with them,

which vibrates as the wave travels. The direction of this vibration is known as

6

polarization and polarized photons can be created by passing a normal beam of light

(which contains photons of many differing polarizations) through a filter set for a specific

Angle of polarization.

Photon

Fig 1.6 Photon Polarization

Light impinging on a filter will either go through and emerge polarized to the angle

of the filter regardless of its original polarization, or will be blocked. The probability of

each result depends on the difference between the polarization angles of the filter and the

incoming photon. For example, if vertically polarized photons are sent through a filter set

at an angle θ to the vertical, the probability of passing through the filter decreases as θ

increases: when θ is 90o, i.e. when the second filter is horizontal, the photon will not pass

through. When θ is 45o, this probability is precisely one half, so the output from the

second filter in this case is exactly the same as it would have been had a randomly

polarized stream of photons been passed through it , it has been randomized.

7

Two bases are conjugate if the measurement of the polarization of one randomizes the

other, and thus are subject to the Heisenberg Uncertainty Principle: measuring one affects

the value of the other, so its impossible to know both values simultaneously. So, for

example, filters set at 0o

and 90o form one basis, and its conjugate basis has filters set at

45o and 135

o. Illustration is being shown in Fig1.3. Photons passing through the first will

emerge with vertical or horizontal polarization, which will then be changed to diagonal

polarization once they have been filtered by the conjugate basis, but 45o or 135

o

polarizations will occur with random probability of 1/2.

Fig 1.7 Photon polarization direction

1.4 KEY DISTRIBUTION

Alice and Bob first agree on two representations for ones and zeroes

One for each basis used,{,} and {, }.

This agreement can be done in public

Define

1 = 0=

1 = 0 =

8

1.5 METHODOLOGY OF QKD

Quantum mechanical effects can be used to transfer information from Alice to Bob,

and any attempted eavesdropping by Eve will always be detectable. Three distinct phases

are needed: raw key exchange, key sifting and key distillation, with the option to discard

the secret key at any of the stages.

Fig 1.8 Flowchart of QKD protocol

i. RAW KEY EXCHANGE

This is the only quantum part of Quantum Key Distribution. Alice and Bob

exchange quantum states using QC. Quantum information is passed along a quantum

channel from Alice to be measured by Bob, with or without the presence of Eve, the

Authentication Key

Quantum state

transmission and

measurement

Key sifting/

reconciliation

Security

parameter

estimation

Error

correction

Privacy

amplification

Secret key

distillable Key

confirmation

Secret key

Abort

9

eavesdropper. In all subsequent exchanges in a protocol, only a secure classical channel

will be used. This is known as ‘classical post-processing’.

Fig1.9 Key Exchange

ii. KEY SIFTING

Alice and Bob decide between them which of the measurements will be used for

the secret key. The decision making rules depend on which protocol is being used, and

some measurements will be discarded e.g. if the settings used by Alice and Bob did not

match.

The Key Sifting stage is done over a public classical channel, where Alice and Bob each

broadcast their choice of basis for each photon. As it is only the basis which is being publicly

discussed, no key information can be gained by an eavesdropper at this point. The bases are

compared, and any photon which had been processed using non-matching bases is dropped from

the raw key material. The sifting process should, on average, leave half of the exchanged qubits

still available for use in the final secret key.

10

iii. KEY DISTILLATION

When reviewing experimental results protocol needs to be workable even in the

presence of transmission errors .Thus error correction and privacy amplification are

required, which are the first two steps in the key distillation phase of the classical post-

processing of the remaining secret key bits. The third final process is authentication,

which counteracts man-in-the-middle attacks.

1.6 EVALUATION OF THE SRS GENERATED BY A SINGLE TELECOM

DATA CHANNEL

To calculate an important parameter for the performance of QKD systems. The

estimated generated secure key rate as a function of the distance for a QKD system using

decoy-states [12]–[13]. QKD in optical fibers populated with multiple telecom DWDM

channels can be highly unfeasible unless mitigation techniques are employed [8]

Fig 1.10 Setup for evaluation of the SRS generated by a single telecom data channel

The secret key rate for a QKD system employing decoy-states is analyzed for the first

time. This is performed in two configurations, co- and counter-propagating directions

between the classical and quantum signals. The counter-propagation direction can be of

great practical value, such as in some demonstrations of measurement device-

independent QKD [16].Two types of channel used in SRS noise in the quantum channel .

11

One is the single channel and then another one is the multiple channel. Main aim is to

measure all the noise generated from other channels with classical power levels, as seen

at the quantum channel. The laser sources pass through a set of three pairs of optical

isolators and fiber-Bragg gratings (FBG) centered at the quantum channel with 100 GHz

full-width half-maximum (FWHM), in order to carve a spectral notch at this wavelength,

which provides a 60 dB extinction ratio. The isolators are used to avoid the formation of

optical cavities.

12

CHAPTER 2

LITERATURE SURVEY

2.1 IMPACT OF RAMAN SCATTER NOISE FROM MULTIPLE TELECOM

CHANNEL ON FIBER OPTIC QUANTUM KEY DISTRIBUTION SYSTEMS

The impact of the spontaneous Raman scattered noise generated from multiple

optical classical channels on a single quantum key distribution channel, all within the

telecom C-band. Measure the noise generated from up to 14 continuous-wave laser

sources with different wavelengths using the dense wavelength division multiplexing

(DWDM) standard, in both propagation directions in respect to the QKD channel, over

different standard SMF-28 fiber lengths. Simulate the expected secure key generation

rate for a decoy states based system as a function of distance under the presence of

simultaneous telecom traffic with different modulation techniques, and show a severe

penalty growing with the number of classical channels present.

For in-band coexistence, the telecom channels should be distributed as close as

possible from the quantum channel to avoid the Raman noise peaks. Operation far from

the zero dispersion wave length of the fiber is also beneficial as it greatly reduces the

generation of four-wave mixing inside the quantum channel. Furthermore, narrow

spectral filtering on the quantum channels is required due to the harsh limitations of

performing QKD under real telecom environments, with the quantum and several

classical channels coexisting in the same ITU-T C-band.

INFERENCES

To analyze the impact of the spontaneous raman scatter noise generated from

multiple optical channel on a single quantum key distribution using optsim.

The telecom channel should be distributed as close as possible from the quantum

channel to avoid the raman noise peaks.

13

PROBLEM IDENTIFIED

It would be highly desirable to have QKD channel sharing optical fibers together

with telecom data channels.

2.2 TRANSMISSION OF O-BAND WAVELENGTH-DIVISION MULTIPLEXED

HERALDED PHOTONS OVER A NOISE CORRUPTED OPTICAL FIBER

CHANNEL

Transmission O-band heralded photons over 10 km of optical fiber in a proof-of-

concept experiment demonstrating the feasibility of using heralded photons to improve

the noise tolerance of quantum key distribution. The optical fiber channel was corrupted

by noise photons to the extent that if we had used an attenuated laser as the photon

source, a photon signal-to-noise ratio of < 4.0 at the receiver, corresponding to a quantum

bit-error rate of > 10.0%, would have prevented the effective generation of secure keys.

Using a photon heralding scheme, the photon signal-to-noise ratio in our experiment was

shown to be > 7.8. This corresponds to a quantum bit-error rate of < 5.7%, which is good

enough for distilling secure keys. It is possible to incorporate wavelength-division-

multiplexing into the photon heralding scheme to improve overall key rate. Limitations

of the photon heralding scheme for noise tolerant quantum key distribution.

INFERENCES

transmitted O-band heralded photons over 10 km of optical fiber in a proof-of-

concept experiment demonstrating the feasibility of using heralded photons to

improve the noise tolerance of quantum key distribution.

PROBLEM IDENTIFIED

The optical fiber channel was corrupted by noise photons to the extent that if we

had used an attenuated laser as the photon source, a photon signal-to-noise ratio of

< 4.0 at the receiver, corresponding to a quantum bit-error rate of > 10.0%, would

have prevented the effective generation of secure keys.

14

Internet services coexist on the same fiber without having to impose any

restrictions on the Internet services. This shall allow non-disruptive introduction of

QKD into existing fiber optic networks and accelerate wide-spread deployment of

QKD systems.

2.3 QUANTUM ENTANGLEMENT DISTRIBUTION WITH 810 NM PHOTONS

THROUGH ACTIVE TELECOMMUNICATION FIBERS

Distribution of polarization-entangled photons for the purpose of quantum key

distribution (QKD) along active telecom fibers. Entangled photon pairs of 810 nm

wavelength generated by a SAGNAC interferometer source were coupled into standard

telecom single mode fibers. The fibers were either dark or carrying a standardized 1550

nm Ethernet signals (1000BASE-ZX) with a nominal speed of 1 GBps from regular

media converter devices, without any requirements on the optical power or spectrum

transmitted. Our system demonstrates a QKD network covering 6 km in distance with a

central service provider for classical and quantum data.

INFERENCES

The distribution of polarization-entangled photons for the purpose of quantum

key distribution along active telecom fibers. Our system demonstrates a QKD

network covering 6 km in distance with a central service provider for

classical and quantum data.

Most fiber-based implementations of QKD use ‘dark fibers’ dedicated solely to

quantum information [10, 11], an expensive usage of resources, or use parts of

the optical spectrum which currently have low volume of traffic[12, 13,14,15,].

15

PROBLEM IDENTIFIED

Noise cancellation or power regulation of the classical signal are required to

counteract this effect. Additionally, difficult to operate In GaAs photon detectors

or superconducting detectors must be used for these longer wavelength photons

2.4 QUANTUM CRYPTOGRAPHY

Quantum cryptography could well be the first application of quantum mechanics at

the single-quantum level. The rapid progress in both theory and experiment in recent

years is reviewed, with emphasis on open questions and technological issues.

Cryptography is art of devising codes and ciphers. Crypto analysis is the art of breaking

them . Cryptology is the combination of the two. That is cryptography and crypto

analysis

INFERENCES

Security principle relies on information theory and on a Heisenberg’s

uncertainty principle.

PROBLEM IDENTIFIED

Keys can be exchanged over distances of kilometers at a rates of thousand bits per

second

2.5 LONG DISTANCE PRACTICAL QUANTUM KEY DISTRIBUTION BY

ENTANGLEMENT SWAPPING

Develop a model for practical, entanglement-based long-distance quantum key

distribution employing entanglement swapping as a key building block. Relying only on

existing off-the-shelf technology, we show how to optimize resources so as to maximize

secret key distribution rates. The tools comprise lossy transmission links, such as telecom

optical fibers or free space, parametric down-conversion sources of entangled photon

16

pairs, and threshold detectors that are inefficient and have dark counts. Our analysis

provides the optimal trade-off between detector efficiency and dark counts, which are

usually competing, as well as the optimal source brightness that maximizes the secret key

rate for specified distances (i.e. loss) between sender and receiver.

INFERENCES

Entanglement-based long distance quantum key distribution employing

entanglement swapping as a key building block. To optimize resources so as to

maximize secret key distribution rates.

PROBLEM IDENTIFIED

The tools comprise lossy transmission links, such as telecom optical fibers or free

space, parametric down-conversion sources of entangled photon pairs, and

threshold detectors that are inefficient and have dark counts.

2.6 MULTIPLEXED CLASSICAL AND QUANTUM TRANSMISSION FOR HIGH

BITRATE QUANTUM KEY DISTRIBUTION SYSTEMS

Quantum key distribution (QKD) provides a unique way for secure communication.

During the past decade, rapid progress has been made towards the goal of a stable, high bit rate

QKD system for real-world applications.

QKD system uses the BB84 protocol with decoy pulses and phase encoding. The

quantum transmitter, Alice produces 1550nm optical pulses operating at the system clock rate of

1GHz. Information is imparted through phase encoding; achieved by the use of an Asymmetric

Mach-Zehnder Interferometer (AMZI). At the quantum receiver’s side, Bob, the information is

decoded using a matching AMZI before being detected by two single photon detectors. In GaAs

avalanche photodiodes are used as these detectors permit high speed gating at GHz clock

frequencies with low after pulsing.

The operation of a gigahertz clocked quantum key distribution system, with three

classical channels using coarse wavelength division multiplexing over a fiber distance of 80km.

17

INFERENCES

QKD must be able to share a single fiber with classical data communication. This

will allow the usage of existing fiber infrastructures, thereby reducing the capital

and operational cost for QKD system installation.

PROBLEM IDENTIFIED

A secure key rate of 72kbit/s is not achieved in presence of classical

communication channels.

2.7 TOWARDS THE MODELING AND SIMULATION OF QUANTUM KEY

DISTRIBUTION SYSTEMS

Quantum Key Distribution (QKD) is a next generation security technology that exploits

the properties of quantum mechanics to enable two parties to generate an unconditionally secure

shared secret key. QKD is novel because its security is based upon the fundamental laws of

quantum mechanics and not on computational complexity. QKD systems are composed of

multiple interconnected electrical, optical, and electro-optical subsystems and computer-based

controllers and can be viewed as a complex system (or system of systems). Currently, there is no

single simulation framework that supports a high level systems engineering analysis of QKD

system architectures. Cryptography, the practice and study of techniques for securing

communications between two authorized parties in the presence of one or more unauthorized

third parties, is the centerpiece of a centuries old battle between code makers and code breakers.

The strength of commonly used modern cryptographic algorithms relies on computational

security, which means the algorithms are considered secure if there is a negligible probability of

discovering the key in a reasonable amount of time using current computational technology.

INFERENCES

An evaluation process that considers end user and software developer requirements for

the identification and selection of a software framework suitable for modeling,

simulation, and analysis of QKD systems.

18

PROBLEM IDENTIFIED

The need to evaluate different QKD system implementations coupled with the cost of the

systems, the cost of testing, the uniqueness of each system implementation, and the

relative scarcity of resources creates a problem: How does one design, develop, test, and

analyze QKD systems in a resource-constrained environment.

2.8 OPTICAL NETWORKING FOR QUANTUM KEY DISTRIBUTION AND

QUANTUM COMMUNICATIONS

Modern optical networking techniques have the potential to greatly extend the

applicability of quantum communications by moving beyond simple point-to-point optical links

and by leveraging existing fiber infrastructures. Here they, experimentally demonstrate many of

the fundamental capabilities that are required. These include optical-layer multiplexing,

switching and routing of quantum signals; quantum key distribution (QKD) in a dynamically

reconfigured optical network; and coexistence of quantum signals with strong conventional

telecom traffic on the same fiber. They identify the dominant impairment as spontaneous anti-

Stokes Raman scattering of the strong signals, quantify its impact, and measure and model its

propagation through fiber. They describe a quantum networking architecture which can provide

the flexibility and scalability likely to be critical for supporting widespread deployment of

quantum applications.

The ultimate usefulness of most communications services depends strongly on the ability

to network, i.e. to efficiently connect many end users with each other or with shared resources.

Efficient networking solutions are clearly needed to move QKD and other types of quantum

communications beyond the realm of deployments.

INFERENCES

Successful operate QKD at 1310 nm over a fiber shared with four optically amplified

data channels near 1550 nm.

The experimental research on quantum key distribution (QKD) has focused on improving

transmission performance over a fixed end-to-end connection between a single pair

of quantum endpoints, Alice and Bob.

19

PROBLEM IDENTIFIED

This type of connectivity does not scale well, because the level of resources that are

required increases very rapidly with the number of end users.

20

CHAPTER 3

SOFTWARE - OPTSIM

3.1INTRODUCTION

The project deals with the QKD system, which provides secured communication

between two parties by the exchange of secret key using quantum channel (eg: optical

fiber).This system deals with the implementation of single data telecommunication

channel using simulation package Optsim5.2. Optsim software provides variety of optical

communication modeling and simulation. Optsim consists of variety of components

related to photonic telecom components.

3.2 OPTSIM 5.2

OptSim, RSoft's award-winning software tool for the design and simulation of

optical communication systems at the signal propagation level empowers the users with

models and simulation techniques that are specifically designed for PM-QPSK and other

advanced modulation formats including OFDM, D(Q)PSK and duo binary. It is basically

an advanced optical communication system designed for professional engineers. It can be

used to design optical communication systems and simulate them to determine their

performance given various component parameters. With user friendly simulation

techniques and easy-to-use graphical user interface, OptSim provides unmatched

flexibility and usability.

3.2.1 FEATURES

Performance analysis (e.g. Q value, BER, Power spectra and OSNR, eye diagram).

Wide and complete choice of measurement (e.g. jitter, eye opening/closure,

electrical/optical spectra, chirp, optical instantaneous phase/frequency and power).

Link optimization: power budget, dispersion map, tailoring of pulse shape and

chirp, transmitter pre-emphasis, amplifier positioning.

21

Transmission impairment analysis and assessment of countermeasures (e.g. All-

order PMD, SPM, XPM, FWM, Stimulated Raman Scattering effect)

Edge design and validation System sensitivity evaluation

Extensive library of predefined manufacturer components makes it easy to model

commercially available devices

3.2.2 SIMULATION ENGINES

The twin simulation engines support two complementary simulation approaches.

Block mode simulation engine: The signal data is represented as one block of

data and is passed between block to block. Nonlinear fiber is simulated using the

Split Step Fourier technique in this mode.

Sample mode simulation engine: The signal data is represented as single sample

that is passed between block to block.

Block mode simulation engine is used in the implementation QKD.

3.2.3 RESULTS ANALYSIS AND POST PROCESSING

Stage 1: Modeling preliminaries

Stage 2: Performance Evaluation

Stage 3: Optsim Validation

3.2.4 COMPONENT DESCRIPTION

CW LASER: This model produces the optical signal output of one or more CW

lasers. It is most commonly used in conjunction with the external modulator model to

encode a binary signal upon the CW source.

MODULATOR: This models an electro-optic modulator. Several types of

modulators may be modeled with this block, including the Mach-Zehnder type. When

using the modulator model with the mode-locked laser model, the user must ensure that

the number of samples per bit and the bit sequence pattern width for both the binary

sequence generator and the mode locked

22

laser model are the same.

NONLINEAR FIBER: This model provides a detailed implementation of

propagation of one or more optical channels in a single mode fiber. It takes into account

attenuation, dispersion, polarization mode dispersion (PMD) and nonlinearities including

Raman effects. When the Single-Channel mode of the MUX is used prior to the fiber

model, it also takes into account four wave mixing. Bi-directional effects, especially

Raman amplification, should be modeled using the Bidirectional Nonlinear Fiber Model.

PRBS PATTERN GENERATOR: This model generates a binary sequence of

several different types. A single model instance may be used to provide multiple pattern

outputs, optionally offset from each other, to drive different channels of a WDM or

parallel optical bus simulation. Or, each channel may have its own model instance

configured to provide a different pattern than the other model instances.

ELECTRICAL SIGNAL GENERATOR: This model converts an input binary

signal into an output electrical signal. The output signal may be specified as either

voltage or current. The user parameters are used to configure the electrical signal output.

OPTICAL ATTENUATOR: This model attenuates the input optical signal by the

specified level of attenuation. This model may be used anywhere in the topology where a

specified level of optical attenuation is desired. It has two parameters. The first and

primary parameter is the attenuation value in units of dB. This attenuation is applied to

the x polarization portion of the signal.

If the signal contains a y polarization component as well, then the second parameter,

xy_differential, is used to set the attenuation of the y polarization component. The

attenuation of the y polarization component (y_attenuation) is expressed as follows:

y_attenuation = attenuation – xy_differential

OPTICAL MULTIPLEXER: This model represents an optical WDM multiplexer

(see also the General Multiport Optical Device described below). It accepts multiple

23

optical signals at its input ports and produces a WDM optical signal at its output port

which includes all the input WDM optical signals.

POLARIZATION TRANSFORMER: This model transforms the polarization of

the input optical signal according to the specified parameters. This model may be used

anywhere in the topology where a specified polarization transformation is desired.

OPTICAL DEMULTIPLEXER: This model represents an optical WDM

demultiplexer .It accepts a WDM optical signal at its input port and produces N single

channel optical signals at its output ports, one channel per port. This is accomplished by

applying the specified filter to the input signal for each of the output ports.

POLARIZATION MONITOR: This model provides the facility to measure a

number of polarization state related properties of an optical signal, specifically

Differential Group Delay (DGD), Degree Of Polarization(DOP), Averaged Stokes

Parameters and Instantaneous Stokes Parameters.

OPTICAL EYE ANALYZER: This model computes a number of useful

parameters related to the noise, signal waveform, and eye diagram of the input optical

signal. These may be plotted vs. the scanned variables by this block.

BIT ERROR RATE TESTER: This model computes the Bit Error Rate for the

input electrical signal as well as a number of useful parameters such as the Q factor and

electrical eye properties such as the height, width, area and extinction ratio. The BER

may be calculated using either a Quasi-Analytical or Monte-Carlo algorithm depending

on the nature of the dominant noise sources in the simulation.

COMPOUND OPTICAL RECEIVER: This models an optical receiver and all

its standard parts. The OptSim photo receiver model is composed of several individual

building blocks: the photo detector, the preamplifier, and the post amplifier/filter.

24

PROPERTY MAP: This model produces maps of dispersion and power along a

fiber link. Frequently we construct links consisting of a series of fibers and amplifiers and

it is useful to monitor the power evolution along the link.This model allows the current

power and dispersion at the output of any component to be recorded and output as a map

along the link.

OPTICAL SPLITTER (1XN): This model represents an ideal optical splitter. It

takes a single input signal, and divides it equally among N output ports with 1/N splitting

loss, plus excess loss determined by the transmission model parameter.

POLARIZATION TRANSFORMER: This model transforms the polarization of

the input optical signal(s) according to the specified parameters. This model may be used

anywhere in the topology where a specified polarization transformation is desired.

25

CHAPTER 4

NOISE IMMUNE SYSTEM

4.1 QKD SETUP

The main objective of this project is to model quantum key distribution [5]

experiments using OptSim which looks simpler in shallow, but their in-built components

are not correlated with QKD operation. Polarization Beam Splitter (PBS) is one of the

prime passive components of the QKD, its functionality is to pass the incoming light

based on its angle. Unfortunately, in OptSim PBS splits the incoming light of photons to

two different angles (Horizontal or Vertical).Some of the available components in the

OptSim library does not execute as QKD components. For these cases, an alteration or

creation of components is required.

OptSim5.2 has some other built in libraries can be utilized for simulation called

visualizers. There are three major classifications in the telecommunication system; they

are transmitter, channel, and receiver. In transmitter block, photon source is the prime

component and OptSim5.2 offers wide variety of optical sources with many inseparable

properties. Attenuation is an indispensable mechanism in QKD[10] to extract a single

photon level from photon pulses. A polarizer is used for the polarization of photon

extracted to the desired direction angle.

Fig 4.1 Implementation of QKD

26

4.2 NOISE IMMUNE QKD

Simulation of noise immune QKD [15] is described below. Noise is considered

one of the biggest challenges in QKD. Distinguishing noise from eavesdropping is an

intrigue research. Noise can come various components, from fiber optic channel i.e.

birefringence, polarization dispersion and free space issues i.e. scattering, absorption,

diffraction, etc. Further, detectors problems like dark count and detection efficiency. As a

summary, noise has various triggering factors which results in poor performance in

QKD especially in secure key generation rate and distance. There have been several

solutions proposed by researches. Implementation of one of experiment and briefly

explained its protocol.

Fig 4.2 Noise immune QKD

27

Bob sent rectilinear basis photon to Alice. Alice passes incoming qubit to faraday

rotator and forward to Bob. Alice also sent unpolarized photon to Bob. The information

about photon is calculated by the polarization basis and time delay between photon. The

property of faraday rotator is given by the following property.

Hin → Faraday Rotator → Vout

Vin → Faraday Rotator → Hout

Here H and V refer to horizontal and vertical basis. In this simulation, the

polarization rotator is inbuilt OptiSystem’s component. The noise immune QKD

simulation is showed in Fig.3.5

Polarization rotator’s property,

0○ – 90

○ = -90

○

90○ – 90

○ = 0

○

Here 0○ and 90

○ refer to rectilinear angles. The utilization of two ‘Time Delay’

components for time difference between photon are being sent. Both components

generate time/value based on value from pseudo random number generator.

28

CHAPTER 5

SINGLE DATA TELECOM CHANNEL

5.1 INTRODUCTION

Quantum key distribution (QKD) enables the generation of a secret key between two

remote parties with security guaranteed by the principles of quantum physics [1]. It can

be of great interest to the telecommunication industry as it can provide. An important

alternative to the key distribution problem in classical cryptography. The widespread

practical deployment of QKD depends heavily on its compatibility with current telecom

optical networks. From a practical point of view, it would be highly desirable to have

QKD channels sharing optical fibers together with telecom data channels. Although many

quantum key distribution demonstrations have been done in “dark” fibers, that is, fibers

devoid of any classical signals, there has been considerable interest in experimentally

investigating QKD performed in fibers with coexisting classical signals [2]. This has

huge benefits in order to minimize the cost of having an entire fiber solely dedicated to a

QKD system.

Fig 5.1 Basic block diagram of single data telecom channel

29

5.2 IMPLEMENTATION OF SINGLE DATA TELECOM CHANNEL

Typically the classical and quantum signals are multiplexed using standard

Wavelength Division Multiplexing Technology (WDM). Two main technical difficulties

arise when trying to multiplex the two types of signals in the same optical fiber. The first

one is related to the fact that the power level difference between a classical signal and the

single-photon level can reach 100 dB, which may lead to extreme crosstalk and even

eventually saturating the single-photon detectors. Cascaded filters, combined with pre-

filtering of the classical channels to remove unwanted broadband spontaneous emission,

is effective in dealing with this issue.

The other hurdle is noise generated from the classical channels when photons are in

elastically scattered due to the spontaneous Raman scattering (SRS) [8], [10]. In this case,

the problem is more complex as the noise is generated in-band with the QKD signal

along the fiber, therefore, it cannot be spectrally filtered out. Different solutions have

been proposed such as: operating in the 1300 nm window outside of the Raman

bandwidth [8], using reduced launch powers for the classical channels and narrowband

filters [11], time interleaving the single photons with the Raman scattered photons [8],

and employing a temporal filter [9].

Fig 5.2 Implementation of single channel

30

In this project, the impact of spontaneous Raman noise generated from multiple

classical DWDM channels on a QKD wavelength, all within the telecom C-band, is

experimentally measured. In this scenario, the secret key rate for a QKD system

employing decoy-states is analyzed for the first time. This is performed co-propagating

direction between the classical and quantum signals.

5.3 WAVELENGTH DIVISION MULTIPLEXING

Wavelength division multiplexing (WDM) is a technology or technique modulating

numerous data streams, i.e. optical carrier signals of varying wavelengths (colors) of laser

light, onto a single optical fiber. Basic concept of wavelength division multiplexing

provide transmit the signal in single data channel using optsim software.

The technology of combining a number of optical wavelength and then transmit the

same through a single fiber is called wavelength division multiplexing .Electrical

generator and laser source connect with together and send the modulation state .It can

perform simply and convert the signal into light source ,in this conversions gives the

result shown in input spectrum analyzer Fig 6.10 . Attenuator is a devise used to reduce

the power level of an optical level either free space or an optical fiber .The basic types of

optical attenuator are fixed ,step wise, variable, and continuously variable .For an

example reduce the strength of a radio or audio signal.

Fig 5.3 Wavelength Division Multiplexing

31

Optical circulator is defined special optical or fiber optic component .that can be used to

separate optical signal that travels in opposite direction an optical fiber. Here we apply

non linear fiber, in this fiber used to reduce the velocity dispersion.non linear test

component gives two wave form shown in Fig 2.6 This is referred as Raman response

spectrum

5.4 DENSE WAVELENGTH DIVISION MULTIPLEXING

Make efficient utilization of bandwidth and low attenuation characteristics of single

mode fiber and use multiple wavelengths as carried and allow them to transmit in the

fiber simultaneously. dense wavelength division multiplexing greatly increase the

network capacity

Fig 5.4 Dense Wavelength Division Multiplexing

32

5.5 CO-COUNTER PROPAGATING USING SAMPLE MODE

Nowadays a lot of research is done on the usage of fiber nonlinearity for optical

amplification. Among all nonlinear optical effects stimulated Raman scattering is of

particular interest, because it can be efficiently used for obtaining high signal gain

combined with low amplifier noise

A comparison has been made between co- and counter-propagating first- and

second-order pumping in U-band lumped fiber Raman amplifiers. It has been shown that

the co-propagating pump scheme results in much higher gain increases, which agrees

with simulation results. In both the co- and counter-propagating pumps schemes, the

noise figure was found to only minimally increase. Believe that second-order Raman

pumping can be beneficial in lumped systems as the gain evolution along the fiber can be

tailored to specific needs. In addition, undesirable nonlinear effects from a single high-

power pump can be suppressed by distributing the pump power between two orders,

while still obtaining high Raman gains.

Counter propagating and co-propagating beams generally mean they have the same

wave vector: for counter propagating beams the wave vector has opposite sign, for co

propagating, the same sign. The gains and noise figures of discrete second-order-pumped

fiber Raman amplifiers utilizing co propagating and counter propagating pump

configurations were experimentally obtained, and the gain results were compared with

computer simulations. It was found that the additional gain that is due to second-order

Raman pumping is larger for the co propagating pumps than for the counter propagating

pumps, in agreement with simulations. In contrast to distributed second-order-pumped

fiber Raman amplifiers, a slight increase in noise figure, by as much as ~1 dB was

observed relative to the single-pump scheme. However, the advantages of second-order

pumping in discrete amplifiers include greater flexibility in design of the gain distribution

along the fiber and the ability to spectrally distribute the pump powers to avoid undesired

nonlinear effects.

33

Fig 5.5 Co-Counter Propagating

Two channel NRZ Wavelength Division Multiplexing transmitter at 10Gb/s with

100Ghz Of channel spacing. Two different Raman configurations are compared .a single

counter propagating Raman pump at 1543 nm with p=500mW. A co-propagating Raman

pump at 1453 with p=500mW which in turn amplifies the signal propagating into the

fiber. Four different power values from 250 to 500mW for the co-propagating pump are

compared

34

CHAPTER 6

SIMULATION RESULTS

6.1 QKD SETUP

The quantum key distribution setup Fig 4.1 implemented using simulation software

OptSim at the input of the optical fiber propagating is shown in Fig 6.1 and the output

spectrum analyzer 2 is shown in fig 6.2

Fig 6.1 Input Spectrum of QKD Fig 6.2 Output Spectrum of QKD

6.2 NOISE IMMUNE QKD

The input to noise immune quantum key distribution from the spectrum analyser in

the Fig 4.2 before noise reduction and the output spectrum derived from the output

spectrum analyser after the reduction of noise is shown below.

Fig 6.3 Spectrum Before Noise Immune

35

Fig 6.4 Spectrum after Noise Immune

6.3 IMPLEMENTATION OF SINGLE DATA TELECOM CHANNEL

The results of implementation of single data telecom channel shown in Fig 5.2 is

given in Fig 6.5. Two main technical difficulties arise when trying to multiplex the two

types of signals in the same optical fiber. The first one is related to the fact that the power

level difference between a classical signal and the single-photon level can reach 100 dB,

which may lead to extreme crosstalk and even eventually saturating the single-photon

detectors. Cascaded filters, combined with pre-filtering of the classical channels to

remove unwanted broadband spontaneous emission, is effective in dealing with this issue.

Fig 6.5 Input at single data communication channel

36

Fig 6.6 Output at single data communication channel

Fig 6.7 Eye Diagram

6.4 WAVELENGTH DIVISION MULTIPLEXING

The result of implementation of Wavelength Division Multiplexing shown in Fig

5.3 is given in Fig 6.12. The best time to make the measurement can be interpreted from

the Eye diagram. SNR can be measured from the eye opening.Signal to noise ratio at the

sampling point also reduced.

Fig 6.8 Input - Wavelength Division Multiplexing

37

Fig 6.9 Output at wavelength division multiplexing

Fig 6.10 Eye diagram

38

6.5 SIMULATION RESULT OF DENSE WAVELENGTH DIVISION

MULTIPLEXING

The results of implementation of Dense Wavelength Division Multiplexing

shown in Fig 5.4 is given in Fig 6.17. The slope indicates sensitive to timing

error,smaller the timing error better is SNR.

Fig 6.11 Input at Dense Wavelength Division Multiplexing

Fig 6.12 Output at Dense Wavelength Division Multiplexing

39

Fig 6.13 Eye Diagram

6.6 SIMULATION RESULT OF CO-COUNTER PROPAGATING

Two channel NRZ Wavelength Division Multiplexing transmitter at 10Gb/s with

100Ghz of channel spacing is implemented. Two different Raman configurations are

compared .A single counter propagating Raman pump at 1543 nm with p=500mW, a co-

propagating Raman pump at 1453 with p=500mW which in turn amplifies the signal

propagating into the fiber. Four different power values from 250 to 500mW for the co-

propagating pump are compared

Fig 6.14 Input at co-counter propagation

40

Fig 6.15 Output at Co-Counter propagation

Fig 6.16 Quality Factor for 130 km

41

Fig 6.17 Eye Diagram for 130km

Fig 6.18 Spectrum Noise Output for 100km

42

Fig 6.19 Quality Factor for 100 km

Fig 6.20 Eye Diagram for 100km

43

CHAPTER 7

CONCLUSION

This project focuses on implementing of noise immune QKD setup using OptSim

5.2 simulation software. Quantum Communication is the art of transferring a quantum

state from one location.The project deals QKD devices can be directly integrated in some

standard access network. The major compensation is that the combination is straight

forward and does not need any alternation as well as the system devices and procedure.

This technique has enabled the first demonstration of QKD with negligible noise. Later,

the impact of the noise generated from optical signal on a QKD channel is simulated.

Therefore, this reproduction structure reduces the execution rate by choose opposite

elements correctly. Further improvement can be done towards an additional possibility to

reduce the detection bandwidth as much as possible. The teleportation procedure cannot

be used to transmit information faster than light but it can be argued that quantum

information presented in unknown state is transmitted instantaneously (except two

random bits to be transmitted at the speed of light at most).

Observing, or measuring, a quantum system will alter its state. Example: the Qubit

when observed, the state of a qubit will collapse to unpredictable random state 1 or 0. If

an eavesdropper Eve tries to tap the channel, this will automatically show up in Bob’s

measurements.In those cases where Alice and Bob have used the same basis, Bob is

likely to obtain an incorrect measurement: Eve’s measurements are bound to affect the

states of the photons.The best configuration is to populate the telecom channels as close

as possible from the quantum one, preferably positioned at longer wavelengths to avoid

the higher Stokes shift peak contribution of the shorter wavelengths.

44

REFERENCES

[1]. Thiago Ferreira da Silva, Guilherme B. Xavier, GuilhermP. Tempor˜ao,and Jean

Pierre vonder Weid,“ Impact of Raman Scattered Noise from Multiple Telecom

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no.13, july 1, 2014

[2]. K. A.Patel, J. F. Dynes, I. Choi, A. W. Sharpe, A. R. Dixon, Z. L. Yuan, R. V. Penty,

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[6]. E. Waks, A. Zeevi, and Y. Yamamoto, “Security of quantum key distribution with

entangled photons against Individual attacks,” Phys. Rev. A 65, 052310 (2002).

[7]. A. Einstein, B. Pqdolsky And N. Rosen, “Can Quantum-Mechanical Description of

Physical Reality Be Considered Complete?”Institute for Advanced Study, Princeton,

New Jersey(Received March 25, 1935).

45

[8]. William Wooters, Wojciech Zurek, “A single quantum cannot be cloned”, Nature

299, 802- 803 (1982).

[9]. N. Gisin, G. Ribordy, W. Tittel, and H. Zbinden, “Quantum cryptography,”Rev.

Modern Phys., vol. 74, pp. 145–195, Jan. 2002.

[10]. H. Zbinden, N. Gisin, B. Huttner, A. Muller, and W. Tittel, “Practical Aspects of

Quantum Cryptographic Key Distribution,” Journal of Cryptology, vol. 13, no. 2,

2000, pp. 207-220.

[11]. J. Anders, H.K. Ng, B.G. Englert, and S.Y. Looi, “The Singapore Protocol:

Incoherent Eavesdropping Attacks,” Arxiv preprint quant- ph/0505069, 2005.

[12]. W.-Y Wang, “Quantum key distribution with high loss: Toward global secure

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[13]. H.-K. Lo, X. Ma, and K. Chen,“Decoy state quantum key distribution,”Phys. Rev.

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[14]. G. B. Xavier and J. P. von der Weid, “Limitations for transmission ofphotonic

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1072, 2010.

[15] .T. Ferreira da Silva, D. Vitoreti, G. B. Xavier, G. C. do Amaral, G. P.Tempor˜ao,

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http://ncatlab.org/nlab/show/William+Wooters

http://ncatlab.org/nlab/show/Wojciech+Zurek

46

WEBSITES

[16]. http://optics.synopsys.com

[17]. http://www.cs.dartmouth.edu/~jford/crypto.html

[18]. http://en.wikipedia.org/wiki/Quantum_cryptography

http://www.cs.dartmouth.edu/~jford/crypto.html

47

LIST OF PUBLICATION

Presented a paper titled “Imapact of noise on Fiber optic quantum key

distribution system,” International Conference on engineering Digital Green Era,

EDGE-2016 in Rajalakshmi engineering college, Chennai.

Documents

IMPACT OF NOISE ON FIBER OPTIC QUANTUM KEY … · 2016-11-01 · system using optsim software The term Wavelength-Division Multiplexing is commonly applied to an optical carrier (which