preschool children's learning behaviors, concept

http://www.leeds.ac.uk/qcn2014

QuantumInformation

Group @ Leeds

International Workshop on

Quantum CommunicationNetworks

QCN2014

School of Electronic and ElectricalEngineering

University of Leeds

9-10 January 2014

International Workshop on Quantum Communication Networks, University of Leeds, 9-10 Jan 2014

1

Day 1 9 Jan 2014

Registration 8:30-onwardElec Eng Foyer

Session 1: Tutorial 9:00-10:00Session Chair: Timothy Spiller, University of Leeds Rhodes LT, Rm G.55

Opening StatementMohsen Razavi, University of Leeds

9:00-9:05

An introduction to quantum key distribution and its challenges (invited)Hugo Zbinden, University of Geneva

9:05-10:00

Coffee Break 10:00-10:30Elec Eng Foyer

Session 2: QKD NetworksSession Chair: Hugo Zbinden, University of Geneva

10:30-12:00Agilent LT, Rm 1.52

Quantum key distribution networks (invited)Andrew Shields, Toshiba Research Europe Ltd

10:30-10:55

QKD in Classic Optical Networks: Two different worlds forever? (invited)Andreas Poppe, Austrian Institute of Technology

10:55-11:20

Quantum communications from ultralow cost to ultralong range (invited)John Rarity, University of Bristol

11:20-11:45

Quantum friendly architectures for passive optical networksMohsen Razavi, University of Leeds

11:45-12:00

Lunch 12:00-13:30Elec Eng Foyer

Session 3: Emerging QKD SystemsSession Chair: Marcos Curty, University of Vigo

13:30-15:00Agilent LT, Rm 1.52

Quantum key distribution with continuous variables: long distance, side channelsand network integration (invited)Eleni Diamanti, CNRS, Telecom Paristech

13:30-13:55

Satellite quantum communications (invited)Paolo Villoresi, University of Padova

13:55-14:20

Measurement-device-independent quantum key distribution and its application toquantum networks (invited)Xiongfeng Ma, Tsinghua University

14:20-14:45

Long-distance measurement-device-independent quantum key distribution withoutquantum memoriesFeihu Xu, University of Toronto

14:45-15:00

Coffee Break 15:00-15:30Elec Eng Foyer

Session 4: Long-haul Quantum CommunicationsSession Chair: Hermann Kampermann, Universität Düsseldorf

15:30-17:00Agilent LT, Rm 1.52

Quantum repeaters and QKD: analysis of secret key rates (invited)Dagmar Bruß, Universität Düsseldorf

15:30-15:55


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How to get performance out of your quantum network? (invited)William Munro, NTT Basic Research Laboratory

15:55-16:12

The role of quantum memories in quantum networks (invited)Kae Nemoto, National Institute of Informatics, Japan

16:12-16:30

Quantum networks with spins in diamondHannes Bernien, Delft University of Technology

16:30-16:45

Ultrafast and fault-tolerant quantum communication across long distancesSreraman Muralidharan, Yale University

16:45-17:00

Poster Session* 17:00-18:00Elec Eng Foyer

Day 2 10 Jan 2014

Session 1: New Avenues for Quantum CryptographySession Chair: Jawoo Joo, University of Leeds

9:00-10:15Agilent LT, Rm 1.52

Quantum digital signatures without quantum memoryErika Andersson, Heriot-Watt University

9:00-9:15

Measurement-device independent quantum cryptography with continuous variablesStefano Pirandola, University of York

9:15-9:30

Continuous-variable quantum key distribution based on EPR entanglementVitus Händchen, Max-Planck Institute

9:30-9:45

Quantum key distribution using microwavesFreya Wilson, University of Leeds

9:45-10:00

Spacetime effects on satellite-based quantum communicationsDavid Bruschi, University of Jerusalem

10:00-10:15

Session 2: Discussion in GroupsDiscussion moderators: see below

10:30-12:30Various rooms

Key challenges of widespread use of QKD will be discussed in groups. Further detailsto follow. Discussions will be around the following themes:

Theme 1: Viable business models

Theme 2: Meeting performance objectives (moderator: William Munro)

Theme 3: Architecture and integration

Theme 4: Going long distance (moderator: Paolo Villoresi)

ELEC Eng, Rm 1.52

ELEC Eng, Rm 2.56

ELEC Eng, Rm 3.52

ELEC Eng, Rm G.70

Lunch 12:30-13:30Elec Eng Foyer

Session 4: Summary and Concluding RemarksSession Chair: Mohsen Razavi, University of Leeds

13:30-15:00Agilent LT, Rm 1.52

Team representatives to report a summary of their discussions; further discussion by all participants

*Posters will be on display throughout both days.


3

Poster Session9 Jan 2014

17:00-18:00Elec Eng Foyer

List of posters:

P1: Proof-of-principle experiment of reference-frame-independent quantum key distribution with phase

coding

Wenye Liang, Shuang Wang, Hongwei Li, Zhenqiang Yin, Wei Chen, Yao Yao, Jingzheng Huang, Guangcan Guo,

and Zhengfu Han, University of Science and Technology of China

P2: Fast implementation of privacy amplification in quantum key distribution

Chun-Mei Zhang1, Mo Li

1, Jing-Zheng Huang

1, Patcharapong Treeviriyanupab

2, Hong-Wei Li

1, Fang-Yi Li

1, Chuan

Wang1, Wei Chen

1, Zhen-Qiang Yin

1, Keattisak Sripimanwat

2, Zheng-Fu Han

1

1Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China

2Optical and Quantum Communications (OQC) Laboratory, National Electronics and Computer Technology Center

(NECTEC), National Science and Technology Development Agency (NSTDA), Thailand

P3: Two-way quantum cryptography with continuous variables: unconditional security and performances at

different wavelengths

Carlo Ottaviani, University of York

P4: Sharing a phase reference in quantum communications based on coherent detection. Applications to

QKD and to the architectural design of quantum networks.

Adrien Marie and Romain Alléaume, Telecom ParisTech

P5: Experimental demonstration of the coexistence of continuous-variable quantum key distribution with an

intense DWDM classical channel

Rupesh Kumar1, Hao Qin

1, Paul Jouguet

1,2, Sébastien Kunz-Jacques

2, Renaud Gabet

1, Eleni Diamanti

1, and

Romain Alléaume1

1LTCI, CNRS - Telecom ParisTech, 46 rue Barrault, 75013 Paris, France

2SeQureNet, 23 avenue d'Italie, 75013 Paris, France

P6: Memory-assisted measurement-device-independent quantum key distribution

Christiana Panayi1, Mohsen Razavi

1, Xiongfeng Ma

2, Norbert Lütkenhaus

3

1School of Electronic and Electrical Engineering, University of Leeds, Leeds, UK

2Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, China

3Institute for Quantum Computing, University of Waterloo, Waterloo, Canada

P7: Long-distance measurement device independent quantum key distribution

Nicoló Lo Piparo and Mohsen Razavi, University of Leeds

P8: QKD with two-segment quantum repeaters

S. Abruzzo, H. Kampermann, D. Bruß

Institut fr Theoretische Physik III, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany

P9: Coherent cavity networks with complete connectivity

A. Beige1, T. M. Barlow

1, E. S. Kyoseva

2, and L. C. Kwek

2,3

1The School of Physics and Astronomy, University of Leeds, United Kingdom

2Centre for Quantum Technologies, National University of Singapore, Singapore

3Nanyang Technological University, Singapore

P10: Repeat-until-success quantum repeaters

David E. Bruschi1,2

, Tom M. Barlow3, Mohsen Razavi

1, and Almut Beige

3


4

1School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK

2Hebrew University of Jerusalem, Jerusalem, Israel

3School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK

P11: Quantum-aided solutions in wireless systems

Dimitrios Alanis, Zunaira Babar, Panagiotis Botsinis, Soon Xin Ng and Lajos Hanzo, University of Southampton

P12: Quantum optical state comparison amplifier

Electra Eleftheriadou1, Stephen M. Barnett

2, and John Jeers

1

1Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, G2lasgow G4 0NG, UK

2School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, UK

P13: Asymmetric state discrimination

Gaetana Spedalieri and Sam Braunstein, University of York

P14: Strategy with recycling for the enhanced setup for creating large-scale W state networks

Sinan Bugu1,2

, Can Yesilyurt1, Volkan Erol

3,4, Azmi Ali Altintas

5and Fatih Ozaydin

6

1Department of Computer Engineering, Okan University, Istanbul, Turkey

2Institute of Science, Istanbul University, Istanbul, Turkey

3Institute of Science, Okan University, Istanbul, Turkey

4Progress R&D Center, Provus Information Technologies, Istanbul, Turkey

5Department of Electrical Engineering, Okan University, Istanbul, Turkey

6Department of Information Technologies, Isik University, Istanbul, Turkey

P15: Enhanced setup for creating large-scale W state networks with Toffoli gates

Firat Diker1, Fatih Ozaydın

2, Metin Arik

3,4

1Institute of Science, Bogazici University, Istanbul, Turkey

2Department of Information Technologies, Isik University, Istanbul, Turkey

3Physics Department, Bogazici University, Istanbul, Turkey

4Physics Department, Isik University, Istanbul, Turkey

P16: Securing Wireless Networks at the PHY Layer

Nabil Romero Zurita, University of Leeds


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Talks Short Abstracts

Day 1 9 Jan 2014

Session 1: Tutorial 9:00-10:00Session Chair: Timothy Spiller, University of Leeds Rhodes LT, Rm G.55

An introduction to quantum key distribution and its challenges (invited)Hugo Zbinden, University of Geneva

Abstract: This talk tries to set the scene for this workshop. I will give a short introduction to QKD for non-specialist and present the state of the art. Then I will outline a few technical and less technical challenges theQKD has to address in order to have a chance to be widely implemented in networks. Finally, I will slip into therole of devil's advocate and ask some provocative questions!

Session 2: QKD NetworksSession Chair: Hugo Zbinden, University of Geneva

10:30-12:00Agilent LT, Rm 1.52

Quantum key distribution networks (invited)B. Fröhlich1,2, J. F. Dynes1,2, M. Lucamarini1,2, K. Pate1l, L. Comandar1, A. W. Sharpe1, I. Choi1, Z. L. Yuan1,2 and A.J. Shields1,2

1Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK2Corporate Research & Development Center, 1 Komukai-Toshiba-Cho, Sawai-ku, Kawasaki 212-8582, Japan

Abstract: We present a scheme for large-scale quantum networks based on a nodal mesh of high bandwidthpoint-to-point links, which are connected to the customer premise by point-to-multipoint access networks.Low cost Quantum Access Networks (QANs) may be realised by connecting multiple transmitters to a singlequantum receiver using passive optical (or DWDM) combiners. We demonstrate continuous operation of aQAN by pre-compensation of phase and polarisation fluctuations at each transmitter and show that it ispossible to connect up to 64 users to a single QAN. We report also on recent progress to use wavelengthmultiplexing to distribute quantum keys on fibre transmitting conventional data with high bandwidths.

Quantum communications from ultralow cost to ultralong range (invited)J.G. Rarity, D. Lowndes, C-Y. Hu and R. NockDept. of Electrical and Electronic Engineering and Centre for Quantum Photonics, University of Bristol, Woodland Rd,Bristol BS8 1UB, UK

Abstract: The secure exchanging of cryptographic keys over fibre or free space is now approaching acommercial reality. One key limitation to significant uptake of commercial systems is cost. In Bristol we havebeen developing a low cost short range key exchange system for consumer applications with transmitter unit(Alice) designed to eventually fit inside a mobile phone or even in a credit card. Such a system could ultimatelysolve much of the ‘skimming’ and ‘card-not-present’ fraud presently funded by banks. I will present recentresults on our system and some future prospects.

Quantum friendly architectures for passive optical networksMohsen Razavi, Nicoló Lo Piparo and Christiana Panayi, University of Leeds

Abstract: Three network architectures, compatible with passive optical networks, for future hybrid quantum-classical networks are proposed and compared. These setups rely on three different schemes for quantum keydistribution (QKD): BB84, entanglement-based QKD, and measurement-device-independent QKD (MDI-QKD). Itturns out that, while for small-to-moderate size networks BB84 supports the highest secret key generationrate, it may fail to support large numbers of users. Its cost implications are also expected to be higher thanother setups. For large networks, MDI-QKD offers the highest key rate if fast single-photon detectors areemployed. Entanglement-based networks offer the longest security distance among the three setups. MDI-QKD is, however, the only architecture resilient to detection loopholes and possibly the most favorable with itsless demanding end-user technology. Entanglement-based and MDI-QKD setups can both be combined withquantum repeater systems to allow for long-distance QKD with no trust constraints on the service provider.Finally, with a small modification to PONs, we show how to make them more quantum friendly.


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Session 3: Emerging QKD SystemsSession Chair: Marcos Curty, University of Vigo

13:30-15:00Agilent LT, Rm 1.52

Quantum key distribution with continuous variables: long distance, side channels and networkintegration (invited)Eleni Diamanti, CNRS, Telecom Paristech

Abstract: The distribution of secret keys with information-theoretic security is arguably one of the mostimportant achievements of the field of quantum information processing and communications. Encoding thekey information on continuous variables, such as the values of quadrature components of coherent states,presents the major advantage that implementations require only standard telecommunication technology,albeit at the expense of complex post-processing procedures. In this talk, we describe recent long-distancecontinuous-variable QKD experiments, which take into account all aspects of a practical scenario, includingfinite-size effects. Furthermore, we discuss progress towards the identification of side channels present in oursystem and development of suitable countermeasures, and demonstrate experimentally the coexistence ofcontinuous-variable QKD with intense wavelength division multiplexed classical channels. These resultsillustrate the suitability of this technology for securing communications in emerging quantum informationnetworks.

Satellite quantum communications (invited)Alberto Dall’Arche, Davide Bacco, Davide Marangon, Marco Tomasin, Francesca Gerlin, Matteo Canale,Nicola Laurenti, Giuseppe Vallone and Paolo VilloresiQuantumFuture Project, Department of Information Engineering, University of Padova, Padova, Italy

Abstract: The modelling of the quantum communications for the ground-to space and the intersatellite linkshas been analysed on the base of extensive calculations and the previous experience on the single-photonexchange with orbiting retroreflectors. For this purpose, the exploitation of novel resources as non maximallyentangled states in the device independent QKD as well, on classical side, of the exploitation of the statistictransformation in the photon arrival time is expected to pave the way for a significant advancement of free-space QKD.

Measurement-device-independent quantum key distribution and its application to quantum networks(invited)Xiongfeng Ma, Tsinghua University

Abstract: The measurement-device-independent (MDI) QKD protocol closes all loopholes on detection at once.In fact, the detectors in a MDI-QKD setup can even be assumed to be in Eve's possession. Here, we presentrecent experimental realizations of MDI-QKD. By developing up-conversion single-photon detectors with highefficiency and low noise, the MDI-QKD protocol is faithfully demonstrated. Meanwhile, the decoy-statemethod is employed to defend attacks on non-ideal source, such as photon-number-splitting attacks. In theend, the system generates more than 25 kbits secure key over a 50 km fiber link. The MDIQKD can adapt to aquantum network setting.

Long-distance measurement-device-independent quantum key distribution without quantummemoriesFeihu Xu, Bing Qi, Zhongfa Liao, and Hoi-Kwong LoCentre for Quantum Information and Quantum Control, Department of Physics and Department of Electrical & ComputerEngineering, University of Toronto, Toronto, Ontario, M5S 3G4, Canada

Abstract: We present a novel and practical method that can make quantum key distribution (QKD) both ultra-long-distance and immune to all attacks in the detection system. This method is called measurement-device-independent QKD (MDI-QKD) with entangled photon sources in the middle. By proposing a model andsimulating a QKD experiment, we find that MDI-QKD with one entangled photon source can tolerate 77dB loss(367km standard fiber) in the asymptotic limit and 60dB loss (286km standard fiber) in the finite-key case withstate-of-the-art detectors. Our method does not require quantum memories and thus can be easilyimplemented in practice.


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Session 4: Long-haul Quantum CommunicationsSession Chair: Hermann Kampermann, Universität Düsseldorf

15:30-17:00Agilent LT, Rm 1.52

Quantum repeaters and QKD: analysis of secret key rates (invited)Dagmar Bruß, Universität Düsseldorf

Abstract: This talk gives an overview of our recent work on secret key rates in the context of quantumrepeaters. We analyse the influence of various parameters on the key rate: on one hand, experimentalimperfections such as gate errors, imperfect detectors and memories are studied [PRA 87, 052315 (2013)], andon the other hand variations of the repeater protocol (different realisations, different distillation strategies[PRA 87, 062335 (2013)]) are investigated. Furthermore, the performance of a two-segment quantum repeaterin the measurement-device- independent scenario [arXiv:1306.3095] is analysed, and the influence ofmultiplexing with short range [arXiv:1309.1106] is discussed.

How to get performance out of your quantum network? (invited)William Munro, NTT Basic Research Lab, Japan

Abstract: Quantum communication—the ability to transmit quantum information—is a primitive necessary forany quantum internet. At its core, quantum communication generally requires the formation of entangledlinks between remote locations. The performance of these links is limited by the classical signalling timebetween such locations, necessitating the need for long-lived quantum memories. Here, we present the designof a communications network that neither requires the establishment of entanglement between remotelocations nor the use of long-lived quantum memories. The rate at which quantum data can be transmittedalong the network is only limited by the time required to perform efficient local gate operations.

The role of quantum memories in quantum networks (invited)Kae Nemoto, National Institute of Informatics, Japan

Abstract: Until recently, it had been believed that long-lived quantum memory was necessary for long-distancequantum communications. The requirements for quantum memory is dependent on the quantumcommunication scheme, and the feasibility of schemes is dependent on the quantum repeater-nodetechnology. In our presentation, with a concrete model of global quantum network using a cavity-baseddevice, we discuss the trade off in resources with and without quantum memories.

Quantum networks with spins in diamondH. Bernien1, B. Hensen1, W. Pfaff1, S. van Dam1, G. Koolstra1, M.S. Blok1, L. Robledo1, T.H. Taminiau1, M.Markham2, D.J. Twitchen2, L. Childress3, and R. Hanson1

1Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands2Element Six Ltd., Kings Ride Park, Ascot, Berkshire SL5 8BP, United Kingdom3McGill University Department of Physics, 3600 Rue University, Montreal, QC H3A 2T8, Canada

Abstract: We present our recent results towards the realization of scalable quantum networks with solid-statequbits. We have entangled two spin qubits, each associated with a nitrogen vacancy center in diamond. Thetwo diamonds reside in separate setups three meters apart from each other. With no direct interactionbetween the two spins to mediate the entanglement, we make use of a scheme based on quantummeasurements: we perform a joint measurement on photons emitted by the NV centers that are entangledwith the electron spins. The detection of the photons projects the spins into an entangled state. We verify thegenerated entanglement by single-shot readout of the spin qubits in different bases and correlating theresults.

Ultrafast and fault-tolerant quantum communication across long distancesSreraman Muralidharan1, Jungsang Kim2, Norbert Lütkenhaus3, Mikhail D. Lukin4, and Liang Jiang5

1Department of Electrical Engineering, Yale University, New Haven, CT 06511 USA2Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708 USA3Institute of Quantum computing, University of Waterloo, N2L 3G1 Waterloo, Canada4Department of Physics, Harvard University, Cambridge, MA 02138, USA and5Department of Applied Physics, Yale University, New Haven, CT 06511 USA


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Abstract: We investigate a new approach to ultrafast quantum repeaters in which information can be

transmitted through a noisy channel without the use of long distance entanglement [Nat. Photon. 6, 777-781

(2012)]. With small encoding blocks, our approach can fault-tolerantly correct both operational and photon

loss errors using a teleportation based error correction procedure at each repeater station [arXiv:1310.5291].

Furthermore, we optimize the resource requirements for this quantum repeater scheme for the generation of

a secure key. Finally, we discuss using multi-level quantum systems and quantum polynomial codes for more

efficient ultrafast quantum repeaters.

Day 2 10 Jan 2014

Session 1: New Avenues for Quantum CryptographySession Chair: Jawoo Joo, University of Leeds

9:00-10:15Agilent LT, Rm 1.52

Quantum digital signatures without quantum memoryErika Andersson1, Robert J. Collins1, Ross J. Donaldson1, Petros Wallden1, Vedran Dunjko1,2, Patrick J. Clarke1,3,John Jeers4, and Gerald S. Buller1

1SUPA, Institute of Photonics and Quantum Sciences, EPS, David Brewster Building, Heriot-Watt University, Edinburgh EH144AS, UK2Now at: Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstr. 21A, A-6020Innsbruck, Austria3Now at: School of Instrumentation Science and Opto-electronics Engineering, Beijing University of Aeronautics andAstronautics, Beijing, China4SUPA, Department of Physics, John Anderson Building, University of Strathclyde, Glasgow G4 0NG, UK

Abstract: Digital signatures ensure that messages cannot be forged or tampered with. They are widely used toprovide security for electronic communications, for example in financial transactions and electronic mail.Signed messages are also transferrable, meaning that if one recipient accepts a message as genuine, then sheis guaranteed that others will also accept the same message if it is forwarded. Digital signatures are differentfrom encryption, which guarantees the privacy of a message. Both are important cryptographic tasks.Currently used classical digital signature schemes, however, only offer security relying on unprovencomputational assumptions. In contrast, quantum digital signatures (QDS), similar to quantum key distribution(QKD), offer information-theoretic security based on the impossibility of perfectly distinguishing between non-orthogonal quantum states. A serious drawback of previous QDS schemes is however that they require long-term quantum memory, making them unfeasible. We present a scheme that does not need quantum memoryand which uses only standard linear optical components and photodetectors, together with an experimentalproof-of-principle demonstration. In the experimental realisation, the recipients measure the distributedquantum signature states using a new type of quantum measurement, quantum state elimination. This showsthat QDS and QKD are similar in terms of experimental feasibility.

Measurement-device independent quantum cryptography with continuous variablesStefano Pirandola, University of York

Abstract: We extend the field of continuous variable quantum cryptography to a more robust formulationwhich can be applied to untrusted networks. We consider two remote parties connected to an untrusted relayby insecure quantum links. To generate correlations, they transmit coherent states to the relay where acontinuous-variable Bell detection is performed. Despite the working mechanism of the relay could be fullytampered and the links subject to optimal coherent attacks, the parties are still able to extract a secret key.Furthermore, our analysis shows that very long distances can be reached when the relay is proximal to one ofthe parties, configuration typical of a mobile device connecting to a public access point. Thus, using thecheapest possible quantum resources, our findings demonstrate the possibility of long-distance high-ratequantum key distribution in network topologies where direct links are missing between two end-users andintermediate relays cannot be trusted.

Continuous-variable quantum key distribution based on EPR entanglementVitus Händchen1, Tobias Eberle1, Jörg Duhme2, Fabian Furrer3, Jan Gniesmer1, Torsten Franz4, Reinhard F.Werner2, and Roman Schnabel1


9

1Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) and Institut für Gravitationsphysik der LeibnizUniversität Hannover, Callinstraße 38, 30167 Hannover, Germany2Institut für Theoretische Physik der Leibniz Universität Hannover, Appelstraße 2, 30167 Hannnover3Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan, 113-00334Institut für Fachdidaktik der Naturwissenschaften der Technischen Universität Braunschweig, Bienroder Weg 82, 38106Braunschweig

Abstract: Continuous-variable (CV) quantum key distribution (QKD) gained a lot of interest in recent years dueto its high detection efficiencies and low dark noise levels. Current implementations use for example standardtelecommunication lasers and modulators and PIN photo detectors, thereby achieving efficient QKD links overseveral tens of kilometers. The scheme I will present in this talk uses entangled states of light at 1550 nmwhich enables low-loss transmission of the quantum states through telecommunication networks. The setupinvolves two squeezed-light sources providing more than 10 dB non-classical noise reduction, each. The twosqueezed states are superimposed at a beam splitter, thereby achieving the strongest CV entanglement sourcecurrently available at the desired detection band. A secure key is generated exploiting thecorrelations/anticorrelations between the field quadratures measured by homodyne detection. A complexlocking scheme provides long term stability of the entanglement level. Furthermore, a switching process wasimplemented to enable the random basis choice for QKD measurements. By applying a recent security proofby Furrer et al., a secret key with security against collective attacks was generated using a post-selectiontechnique. Futhermore, the setup even enables QKD with security against most general attacks wherefor thepostprocessing is currently under development. By coupling one of the entangled beams into a km-scale fibrewe plan to demonstrate the feasibility of QKD based on EPR entanglement in local area networks.

Quantum key distribution using microwavesMatthew Everitt, Freya Wilson, and Ben Varcoe, University of Leeds

Abstract: We are developing a method of key distribution using microwave regimes allowing for long distancecommunication and implementation on current hardware technologies; most continuous variable quantumkey distribution focuses on optical exchanges however microwave communication links have a ubiquitouspresence. The method exploits quantum shot noise properties of measuring a microwave exchange andreconciliation techniques to secure the exchange from an eavesdropper. If biased noise is distributed over thesystem a correlation of signals between communicants Alice and Bob can be identified and it is this we intendto exploit for secrecy. This should allow us to create a secure system for communication using microwaveswith applications across wi-fi networks, mobile phones and satellites.

Spacetime effects on satellite-based quantum communicationsDavid Edward Bruschi1,5, Tim Ralph2, Ivette Fuentes3, Thomas Jennewein4, and Mohsen Razavi51Hebrew University of Jerusalem, 2University of Queensland, 3University of Nottingham, 4University of Waterloo,5University of Leeds

Abstract: We investigate the effects of space-time curvature on space-based quantum communicationprotocols. We analyze tasks that require either the exchange of single photons in a certain entanglementdistribution protocol or beams of light in a continuous-variable quantum key distribution scheme. We find thatgravity affects the propagation of photons, therefore acting as a noisy channel for the transmission ofinformation. The effects can be measured with current technology.


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List of Participants

Participants Affiliation

Alanis, Dimitrios Southampton University

Alléaume, Romain SeQureNet, Paris Telecom

Andersson, Erika Heriot-Watt University

Babar, Zunaira Southampton University

Barlow, Thomas University of Leeds

Beige, Almut University of Leeds

Bernien, Hannes Delft University

Botsinis, Panagiotis Southampton University

Bruschi, David Jerusalem University

Bruss, Dagmar Universität Düsseldorf

Curty, Marcos University of Vigo

Diamanti, Eleni Telecom Paristech

Diker, Firat Bogazici University

Dorenbos, Sander Single Quantum

Eleftheriadou, Electra Strathclyde University

Erol, Volkan Okan University

Everitt, Matthew University of Leeds

Guha, Saikat Raytheon BBN Technologies

Händchen, Vitus Max-Planck Institute

Hanzo, Lajos University of Southampton

Hongyu, Wu Shandong Institute of Quantum Science and Technology Co., Ltd

Joo, Jaewoo University of Leeds

Kampermann, Hermann Universität Düsseldorf

Knot, Paul University of Leeds

Kumar, Rupesh Paris Telecom

Liang, Wen-ye University of Science and Technology of China

Linfield, Edmund University of Leeds

Lo Piparo, Nicolo University of Leeds

Ma, Xiongfeng Tsinghua University

Munro, William NTT Basic Research Lab

Muralidharan, Sreraman Yale University

Navaie, Keivan University of Leeds

Nemoto, Kae National Institute of Informatics, Japan

Ng-SL, SX Southampton University

Ottaviani, Carlo York University

Panayi, Christiana University of Leeds

Pirandola, Stefano York University

Poppe, Andreas Austrian Institute of Technology

Rarity, John University of Bristol

Razavi, Mohsen University of Leeds

Ribordy, Grégoire ID Quantique

Romero-Zurita, Nabil University of Leeds

Shields, Andrew Toshiba Research Europe

Spedalieri, Gae York University


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Spiller, Timothy University of Leeds

Varcoe, Ben University of Leeds

Villoresi, Paolo University of Padova

Wilson, Freya University of Leeds

Xu, Feihu University of Toronto

Zbinden, Hugo University of Geneva

Zhang, Chun-Mei University of Science and Technology of China

Zhang, Yinghua Shandong Institute of Quantum Science and Technology Co., Ltd


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School of Electronic and Electrical Engineering Floor Plan(maps not to scale)


13

University Campus Map


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Sponsors

We are grateful for the financial support of the following sponsors:

Engineering and Physical Sciences Research Council (EPSRC)

EPSRC is the main UK government agency for funding research and training inengineering and the physical sciences, investing more than £800 million a year in abroad range of subjects – from mathematics to materials science, and frominformation technology to structural engineering. Visit http://www.epsrc.ac.uk formore information.

Digital Technologies Innovation Hub

The digital technologies hub at the University of Leeds brings together institutes andresearch groups across several disciplines, all of whom are involved in developinghardware and software. It covers electronics, photonics and electrical systems (EPES)and information and communication technology (ICT). Broadly speaking, EPES focuseson hardware components, while ICT focuses on software components together withtheir alignment with people and processes. Our researchers are partnering with awide variety of companies on projects ranging from early stage research through tohighly applied development work. We are committed to expanding these relationshipsand to developing opportunities with new organisations with the potential to benefitfrom the research carried out into EPES and ICT at the University.

Quantum Communication Technology Co., Ltd., Anhui

Quantum Communication Technology Co., Ltd., Anhui (USTC-QuantumCTech),together with Shandong Institute of Quantum Science and Technology Co., Ltd.(SIQST), is the first and biggest provider of multi-protocol network security productsand services based on quantum technology, in China. The companies produce state-of-the-art quantum communication systems and series of innovative opt-electronicunits with the commercial applications for the financial industry, governmentorganizations and other enterprises, as well as the research applications for thescientific societies.

Initially founded by the Chinese leading quantum physics research group from HefeiNational Laboratory for Physical Science at Micro-scale (HFNL), University of Scienceand Technology of China (USTC), the companies are continually transferring cutting-edge scientific and technical achievements into mature commercial products, makinggreat efforts to promote wide-range applications of quantum technology and formingthe Chinese quantum industry.

Quantum Information Group at Leeds

The Leeds Quantum Information Group (School of Physics and Astronomy, Universityof Leeds) conducts theoretical and experimental research into various aspects ofquantum information processing, and into the implications of the quantum theory ofcomputation for physics itself. Find out more by visiting http://www.qi.leeds.ac.uk/.

QQQ Group at the Institute of Physics

The Quantum Optics, Quantum Information and Quantum Control (QQQ) Groupcovers a broad spectrum of topics, from the foundations of quantum physics andinformation theory, through the investigation and control of fundamental physical andchemical phenomena, to new types of quantum technologies, metrology andstandards.


15

Suggested Topics for Discussion on Key Challenges of

Commercial Quantum Communication Networks

10 Jan 2014, 10:30-12:30

Based on the suggestions received from you, here are 4 themes for the discussion session on the

second day of the workshop. Participants have been tentatively grouped into four teams, one

corresponding to each theme, to discuss the key challenges in each theme. The rationale for the

member allocation has been to have a core group of experts in each team, plus representatives from

other related areas. If you think you definitely want to be in another group, please let the organizers

know. An alphabetic list of theme members can be found at the end of this page.

The format of the discussion sessions would be as follows. Each group will have a discussion

moderator. Team members will pick someone to report back the summary of their discussions to all

participants in the final session. The questions on the list below are simply suggestions to start a

discussion, and where the discussions go from there is under the discretion of the group members.

Moreover, it is suggested that groups discuss other themes among themselves as well if time

permits. Broader discussion on each theme will then be followed in the final session.

Theme 1: Viable business models ELEC Eng, Rm 1.52

Discussion topics may include:

- Applications of QKD along with viable business models, to achieve much wider adoption

- The issue of cost; what would be a manageable cost for service providers and home users?

What the QC industry can offer in 5, 10, and 20 years?

- Rationale of possible technology segmentations in quantum communication networks: Is it

already the time to segment quantum communication technologies (the segments could for

example rely on speed, reach, cost, network compatibility) in the perspective of building

future quantum networks? What could be meaningful segments? How would they position

themselves with respect to border conditions such as the architecture of existing optical

networks and the alleged requirements of quantum memory and quantum repeaters?

Theme 2: Meeting performance objectives ELEC Eng, Rm 2.56


- What is the key rate that we aim to provide users with in different generations of QC

networks? What is the key rate currently needed to keep up with classical applications?

- Operational scenarios in network security where the use of quantum communications can

provide a clear advantage (possibly with other drawbacks) over classical, existing, techniques

in IT security.

- How to establish the initial key with every server? How many key bits are needed per

session? Will we use ASE+QKD? Servers like Google, Amazon,… need to exchange keys with

many users, how do we handle that?


16

Theme 3: Architecture and integration ELEC Eng, Rm 3.52


- The last-mile access network: Compatibility with PONs; Can it be made wireless? Can it be

made mobile?

- Would trusted node solution be acceptable? Right now, in classical networks, we only trust a

few entities (e.g., our email server); with the trusted node approach we have to trust the

service provider and all its nodes; how about cross-border problems? How to deal with

governmental requests/legal obligations for having a back door?

- Optical integration (cost-effective, performance effective) of quantum communications in

modern optical networks

- Compatibility with current networks: packet switching; how do we buffer photons: (in

memories like in repeaters?), or do we measure them (trusted node?)

Theme 4: Going long distance ELEC Eng, Rm G.70


- Experimental issues: that we need memories; conversion; heralding; good detectors

- The quest and appeals of multimodal QKD (e.g., fibre to ground free-space or to space links)

- Fabrication of multi-mode and multiple memories

- How to match the rate of entanglement generation between memories in quantum

repeaters, with that required by home users?

- How to share memory resources in quantum repeaters among many users? What is the

scale of memories, processing and control needed

- How much would it cost?

Tentative list of group members in alphabetic order

Theme 1 Theme 2 Theme 3 Theme 4

Romain Alleaume Erika Andersson Matthew Everitt Dimitrios Alanis

Panagiotis Botsinis Zunaira Babar Paul Knot Almut Beige

David Bruschi Thomas Barlow Rupesh Kumar Hannes Bernien

Volkan Erol Marcos Curty Xiongfeng Ma Dagmar Bruss

Andreas Poppe Eleni Diamanti Keivan Navaie Electra Eleftheriadou

John Rarity Firat Diker SX Ng-SL Vitus Händchen

Gregoire Ribordy Jaewoo Joo Stefano Pirandola Nicolo Lo Piparo

Gae Spedalieri Saikat Guha Mohsen Razavi Sreraman Muralidharan

Timothy Spiller Hermann Kampermann Nabil Romero-Zurita Kae Nemoto

Ben Varcoe Wenye Liang Andrew Shields Christiana Panayi

Chun-Mei Zhang William Munro Hongyu Wu Paolo Villoresi

Yinghua Zhang Carlo Ottaviani Hugo Zbinden Feihu Xu

Freya Wilson


17

Your Feedback

We would be grateful if you could leave us some feedback on the quality and the organization of this

workshop, and how we can improve it in the future.

1. On a scale of 1 (poorest) to 10 (best), how do you score the organization of QCN2014?

1 2 3 4 5 6 7 8 9 10

2. How did you find the quality and the breadth of the talks?

1 2 3 4 5 6 7 8 9 10

3. How about the posters?

1 2 3 4 5 6 7 8 9 10

4. Discussion sessions?

1 2 3 4 5 6 7 8 9 10

5. Breaks and reception?

1 2 3 4 5 6 7 8 9 10

6. The web page?

1 2 3 4 5 6 7 8 9 10

7. If this workshop is going to be run on an annual basis, how long its duration should be?

1 day 2 days 3 days 4 days 5 days

8. What would be an appropriate and reasonable registration fee for such a workshop

(assuming it is over two days)?

£50/€60/$80 £100/€120/$160 £150/€180/$240 £200/€240/$320

9. Will you attend such future events?

No, I won’t. Yes, I will try to.

Please leave any further comments/suggestions on the back of this page.

Thanks for your feedback.

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