Subject A : QKD network control technology

157A-T02Next generation QKD core- and access-networks

Toshiba Corporation (Andrew Shields)

Our role in the Secure Photonic Network Project is to develop next generation (Gen-III) QKD systems with improved reliability, security and ease-of-use. Future customers require not only high secure key rates, but that this key rate is always available - 24 hours a day and 7 days a week. Furthermore, current QKD hardware, which has previously been realised for high performance over short periods, requires a redesign to ensure long operating lifetimes with no, or minimal, maintenance. This NICT commissioned research project will improve the reliability and stability of QKD. We will develop active stabilisation technology to allow operation of QKD under different ambient conditions. Reliability will be improved by integrating the electronics into a small number of PCBs and by introducing methods to monitor critical components. We will also study the implementation security of QKD and introduce countermeasures against the most significant side channel attacks. Real world application also requires the system to be easy to use by non-experts. We will refine the control software to allow automatic set-up and recovery from system failure. The reliability, stability and security will be tested by field trials on installed fibre. We will also explore techniques for building larger-scale networks using Quantum Access Networks.

Interim results for Team 157A-T02

Task title	Outcome	Date	Note
1: Active stabilisation technology	New analogue electronics	Sep. 2012	Gen-II system delivered and installed for evaluation in Tokyo QKD Network
	FPGA electronics	Sep. 2012
	Control software	Jan. 2013
	Assembly Gen-II system	Jan. 2013
2a: Quantum core network	T12 protocol theory (Fig. 1(a))	Sep. 2012	Proc. SPIE 8542, 85421K (2012).
	Experimental implementation of T12 protocol (Fig. 1(b))	Aug. 2013 Oct. 2013	QCrypt 2013 Optics Express 21, 24550 (2013)
2b: Quantum access network	Quantum access network result published in Nature. (Fig. 2)	Sep. 2013	Nature 501, 69 (2013).
3: Evaluation of QKD systems in the Tokyo QKD Network	Operation of the Gen-II QKD system in the Tokyo QKD Network	Sep. 2013	The Gen-II system was actually installed in Jan 2013

Task 2a: We have developed the efficient "T12" protocol with composable and quantifiable security. The protocol features decoy-states, threshold detectors, and finite-size analysis. With a block size of merely 1.4x10⁵ detected counts the protocol allows a positive secure key rate (Fig. 1a). The bit rate will reach 85% of the asymptotic limit when the block size is 100 Mbits. Figure 1(b) shows an efficiency improvement of 78% for the "T12" protocol as compared with the standard decoy protocol. At a security level quantified with a failure probability of ε=10¹⁰ we have achieved a secure key rate of 1.09 Mb/s over a fibre length of 50 km.

Task 2b: Our study on quantum networks shows that novel quantum access network technology (Fig. 1a) allows up to 64 users to share a detector (Fig. 2b), enabling to scale up quantum networks significantly.

Targets for Team 157A-T02

Task title	Work/Milestone	Due Date	Note
1: Active stabilisation technology	Refine technology for active stabilisation of the interferometer arm lengths, polarization and detection synchronization in QKD systems.	Mar. 2016
2: Quantum core network	Develop QKD prototype with a key distillation system satisfying practical security criteria/considering finite key size effects/countermeasures to secure against side-channel attacks. Introduce methods to monitor critical components for failure and automatic start up procedures.	Mar. 2016
3: Evaluation of QKD systems in Tokyo QKD Network	Operation of Gen III QKD prototype on installed fibre network.	Mar. 2016