1. Quantum Communications Hub
National Network of Quantum Technologies Hubs:
Quantum Communications Hub
Director: Professor Tim Spiller
Affiliation

2. Quantum Communications Hub: Partners
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Quantum Communications Hub: Partners
Academic partners:
York (lead), Bristol, Cambridge, Heriot-Watt, Leeds, Royal Holloway, Sheffield, Strathclyde
Industrial partners:
R&D: Toshiba Research Europe Ltd. (TREL), BT and the National Physical Laboratory (NPL)
Network: ADVA, NDFIS
Supplier/Consultancy (optical): Oclaro, ID Quantique
Collaboration/Consultancy (microwave): Airbus, L3-TRL
Start-ups (exploitation): Qumet (Bristol), Cryptographiq (Leeds/IP Group)
Standards/Consultancy: ETSI, GCHQ
User engagement: Bristol City Council, Knowle West Media Centre, Cambridge Science Park, Cambridge Network Ltd

3. Quantum Communications Hub
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Quantum Communications Hub
Vision:
“To develop new quantum communications (QComm) technologies that will reach new markets, enabling widespread use and adoption in many scenarios – from government and commercial transactions through to consumers and the home.”
Delivery:
First generation: Take proven concepts in Quantum Key Distribution (QKD) and advance these to commercial-ready stages. (Work packages 1-3)
Next generation: Explore new approaches, applications, protocols and services – beyond QKD. (Work package 4)

4. Quantum Key Distribution (QKD)
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Quantum Key Distribution (QKD)
Secure sharing of a key between two parties (Alice and Bob!)
The quantum part is the distribution of the key, with a promise from quantum physics that only Alice and Bob have copies.
Once distributed, the (non-quantum) uses of the key(s) cover a wide range of secure information tasks: communication or data encryption, financial transactions, entry, passwords, ID/passports…
The keys are consumables (use once only for security), so need regular replenishment, which is “quantum”.

5. Quantum Communications Hub: Work packages
WP1 Short Range Consumer QKD (WP Lead: John Rarity (Bristol))
Near infra red, line-of sight
Microwave
WP2 Chip Scale QKD Components (WP Lead: Mark Thompson (Bristol))
Chip scale optics
Network switches
WP3 Quantum Networks (WP Lead: Andrew Shields (TREL))
Quantum Core Networks
Quantum Metro Networks
Quantum Access Networks
WP4 Next Generation QComm (WP Lead: Gerald Buller (Heriot-Watt))
Quantum digital signatures
Quantum Relays, Repeaters and Amplifiers
Device Independent and Measurement-device independent QKD

6. Quantum Communications Hub: Work packages
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Quantum Communications Hub: Work packages
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7. WP1: Quantum secured key exchange for consumers
<€3000
<€10
Could use one-time-pad to protect the PIN
Generate one-time-pad using quantum secured key exchange
Key exchange at ATM allows user to ‘top-up’ a personal one-time-pad.

8. WP1: Why?
Weekly ‘top-up’ a personal one-time-pad into a personal phone/card.
Protects against ‘skimming’
Type your PIN into YOUR device
Absolute security for PIN online
Low cost: free to all customers
The competition:
present readers provide simplistic security based on ‘toy’ codes.
In shops: data between card and reader NOT encrypted during a transaction, PIN is sent in the clear!
See
See also google/vodafone: phone=wallet
Hacking demo

9. Bob meets Alice

10. WP1: The credit card Alice
New System:
Target 3x20x40mm Alice
>100MHz operation

11. WP1: Flexible receiver and software concept:
Standard 19” rack system with replaceable
receiver and software sub-units

12. WP2 Vision: Chip-based Qcomms devices
Integrated quantum photonic
Qcomms chip
1mm
Current approach

13. WP2: Compact chip-based QKD
Chip-based devices for:
Low cost
Compact
Energy efficient
Mass-manufacture
Compatibility with current microelectronic devices
Hub will target:
Fully integrated and packaged QKD devices with control electronics
Deployment in real networking situations

14. WP2: Targeted Applications
Mobile devices
Computer networks
City wide communications network

15. WP2: Chip-based QKD/WDM switches
4x4 building block
16x16 integrated
switch
Compact switching device for reconfigurable quantum networks
InGaAsP devices based on Clos switching architecture

16. WP3: Quantum Networks
Today: Point-to-point fibre QKD links

17. WP3: Quantum Networks
Explore integration of QKD in different network segments
(long-haul, metro, access)
Key management and security analysis of extended trusted node network
Application development, eg layer 3 encryption, quantum digital signatures
Multiplex quantum signals on conventional DWDM grid . .
data
Provisioning of quantum and data channels
quantum
DWDM
DWDM

18. WP3: UK Quantum Network
Establish large-scale Quantum Network test-bed in UK
Implemented in stages
Metro networks in Cambridge and Bristol
Long-haul network connecting Cambridge-London-Bristol (NDFIS) with possibility to extend
Access networks providing multi-user connectivity
TREL
Cambridge
Martlesham
(BT)
UCL
Bristol
Reading
Telehouse
NPL
Southampton
A focus for application development, industrial standardisation and user engagement
Potential test-bed for the other QT Hubs and associated projects

19. Untrusted Measurement Unit
WP 4: Emerging Quantum Communications Technologies
Quantum Digital Signatures Information Theoretic Secure Digital Signatures
Quantum Repeaters Amplifiers for Quantum Communications Systems 𝑝 𝑥
Noiseless amplifier
Quantum
limited
amplifier
Classical
Coherent states
|ΨAlice>
Bob
Verify
Alice
|ΨAlice>
Charlie
Measurement Device Independent Quantum Key Distribution Cryptographic Key Exchange in an Untrustworthy World
Several km
Alice
Bob
Untrusted Measurement Unit
Several km

20. Quantum Comms Hub: Theory and Security Analysis
Contributes to all four Technology Workpackages:
Identify and remove security vulnerabilities at an early stage
Contribute to ETSI standards for QKD and other Qcomm systems
Physical level security analysis
Match physical models for analysis to practical implementations
Widely applicable channel analysis with side channel information leakage studies
Analysis of attacks and countermeasure design
Protocol level security analysis
Analysis of protocol stacks, incorporating low-level quantum and higher level conventional protocols
Analysis of practical security advantages of new protocols such as QDS and MDIQKD
“Quantum-immune” conventional (classical) protocols
Hybrid system analysis
High speed (Gb/s upwards) systems combine QKD and conventional secure communications protocols, trading unconditional and forward security for speed
Detailed security analysis of such hybrid systems (and mitigation against security “loss”) is needed

21. Quantum Communications Hub: Work package targets
“Commercial-ready” QKD technologies...
WP1 Short Range Consumer QKD
Handheld system, leading to minimal mobile phone modification for Alice
Microwave quantum secure communications analysed and demonstrated
WP2 Chip Scale QKD Components
Chip scale Alice with semi-bulk Bob, leading to fully packaged chip scale QKD optical modules
Network switches demonstrated on the UKQN
WP3 Quantum Networks
High bit rate link encryption
Quantum Metro Networks demonstrated in Bristol and Cambridge
Establishment and operation of the UKQN
WP4 Next Generation Quantum Communications
Quantum digital signatures deployed at Metro Network level
Quantum Relays/Repeaters for weak pulse QKD demonstrated on UKQN
Device Independent and Measurement-device independent QKD deployed at QAN level

22. Note: standard slide format – flexible - e
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Title
Text

23. Note: standard slide format – flexible - e
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24. Partners Note: Logos to add/be supplied.
8x University, and industry / funding body partners.
Grid format – and locked in place (master template option).
Partners
[PARTNER LOGO]

25. Quantum Communications Hub
The UK National Quantum Technologies Programme
aims to ensure the successful transition of quantum technologies
from laboratory to industry. The programme is delivered by
EPSRC, Innovate UK, BIS, NPL, GCHQ, DSTL and the KTN.
National Network of Quantum Technologies Hubs:
Quantum Communications Hub
Director: Tim Spiller
Main partners: York (lead), Bristol, Cambridge,
Heriot-Watt, Leeds, Royal Holloway, Sheffield,
Strathclyde,
Toshiba Research Europe Ltd. (TREL),
BT and the National Physical Laboratory (NPL)

26. QCrypto – Example Key Distribution
Alice and Bob use alternative bases of individual photonic qubits
(e.g. plane polarization) to keep Eve guessing (BB84 protocol).
Alice sends photons one by one, chosen at random from
Bob chooses to measure polarization in basis or chosen at random.
Bob announces publicly his list of bases used, but not his results! (Null results are identified and discarded.)
Alice tells Bob which data to keep, those where he used the basis in which she transmitted.
They agree a protocol for 0,1 in each basis to obtain a shared bit string, the raw quantum transmission (RQT).
| >
| >
| >
| >

27. QCrypto – Example Key (BB84)
| > = 1
| > = 0
| > = 0
| > = 1

28. QCrypto – Eavesdropping
Eve cannot clone qubits, but she can try the same as Bob --- guess a basis at random from or , measure the polarization and then send on a photon to Bob polarized as per her result.
Out of the results which Alice and Bob keep, Eve will guess wrong (on average) half of the time. Out of these (through measurement in the wrong basis), Bob will (on average) project half of these photons back to the original state transmitted by Alice. Eve therefore corrupts 25% of the RQT which she intercepts.
More involved eavesdropping strategies also leave evidence: the irreversibility of quantum measurement ensures that Eve cannot gain information without causing disturbance.

29. QCrypto – Errors and key distillation
Using the public channel, A and B can:
- Estimate Eve’s activity
- Detect and eliminate errors in the RQT
- Distil a highly secure key
However, this costs! For every bit of information revealed publicly, a component bit is discarded to avoid increasing Eve’s information. -6
e.g. 4% RQT errors: > 754 bits (Eve knows ~10 bit)
8% RQT errors: > 105 bits (Eve knows ~10 bit) -6

30. WP4: MDI-QKD
Current QKD systems secure the fibre, but equipment must be physically secure
& several “hacks” on detectors demonstrated
Alice
Bob
Eve’s domain
Measurement Device Independent (MDI) QKD relaxes the requirement to trust the detectors. (The detectors can even be operated by Eve)
Alice
Bob
Measurement Unit BS
PBS D1 D2 D3 D4
Mitigates all attacks on the detectors.
We plan to demonstrate a practical and efficient system for MDI-QKD.
Complimented by theoretical analysis of MDI-QKD, as well as complete DI-QKD.

31. WP 4: Quantum Digital Signatures
Bob
|ΨAlice>
Alice
|ΨAlice>
Charlie
Authentication
A receiver believes the message was from a known sender.
Non-repudiation
A sender cannot deny sending a message, without claiming that the private key has been compromised.
Integrity
The message was not altered in transit.
Transferable
The message is transferrable: Bob can be sure that if he forwards the message to Charlie, then Charlie will also accept the message as genuinely from Alice.

32. Phase encoded coherent states: “A quantum one-way function”
WP 4: Quantum Digital Signatures
Phase encoded coherent states: “A quantum one-way function”
Alice
Classical
List of Phases
Difficult
Easy
Set phases
Measure phases π
π/2
3π/2
Phase
Intensity
Bob & Charlie
Coherent States
The lower the intensity, the harder it is to distinguish between the phases of the coherent states

33. WP 4: Quantum Repeaters
Classical amplifier: Increases the amplitude of the signal
Quantum amplifier: A perfect amplifier would violate the No-cloning Theorem
Original
Perfect copy
Imperfect copy
We pay the price in the form of noise:
Classical: noise is added from the technical limitations of the equipment
Quantum: Heisenberg’s relation prevents exact knowledge of the signal, i.e. intrinsic noise
Solution: Non-deterministic (or probabilistic) amplifier
Keep the success probability low 𝑝 𝑥
Noiseless amplifier
Quantum
limited
amplifier
Classical
Coherent states

34.  ?  WP 4: Quantum Repeaters Subtraction Vacuum Detector Comparison
𝑡√2𝛼⟩ ⟨𝑡√2𝛼
𝑡≈1
“1”
𝑟≈0
Vacuum
Subtraction
Detector
𝑝 1 √2𝛼⟩ ⟨√2𝛼 + 𝑝 2 0⟩⟨ 0 
𝑝 1 > 𝑝 2
𝛼⟩ ⟨𝛼 ? 
Imperfect Indication of Amplification
“0”
−𝛼⟩ ⟨−𝛼
Comparison
Detector
𝛼⟩ ⟨𝛼

35. WP 4: Quantum Teleportation
RM Stevenson, J Nilsson, AJ Bennett, J Skiba-Szymanska, I Farrer, DA Ritchie, AJ Shields
arXiv preprint arXiv:

36. References for WP 4
P J Clarke, R J Collins, V Dunjko, E Andersson, J Jeffers and G S Buller, Nature Comm. 3, 1174 (2012).
V Dunjko, P Wallden and E Andersson, Phys. Rev. Lett. 112, (2014).
E Eleftheriadou, S M Barnett and J Jeffers, Phys. Rev. Lett. 111, (2013).
R J Donaldson et al., Experimental Implementation of a Quantum Optical State Comparison Amplifier, arxiv:
C L Salter et al. An entangled-light-emitting diode, Nature 465, 594–597 (2010).
M Stevenson et al.,Nature Comm. 4, 2859 (2013).