Research and Development


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

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.

Theoretical and experimental performance of the T12 protocol.

Fig. 1Theoretical and experimental performance of the T12 protocol.

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.

Architecture of the Quantum Access Network and results of laboratory experiment.

Fig. 2Architecture of the Quantum Access Network and results of laboratory experiment.


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  



Chart 1Schedule for Team 157A-T02