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Intrinsic mitigation of the after-gate attack in quantum key distribution through fast-gated delayed detection

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Koehler-Sidki, A 
Dynes, JF 
Martinez, A 
Lucamarini, M 
Roberts, GL 

Abstract

The information theoretic security promised by quantum key distribution (QKD) holds as long as the assumptions in the theoretical model match the parameters in the physical implementation. The superlinear behaviour of sensitive single-photon detectors represents one such mismatch and can pave the way to powerful attacks hindering the security of QKD systems, a prominent example being the after-gate attack. A longstanding tenet is that trapped carriers causing delayed detection can help mitigate this attack, but despite intensive scrutiny, it remains largely unproven. Here we approach this problem from a physical perspective and find new evidence to support a detector's secure response. We experimentally investigate two different carrier trapping mechanisms causing delayed detection in fast-gated semiconductor avalanche photodiodes, one arising from the multiplication layer, the other from the heterojunction interface between absorption and charge layers. The release of trapped carriers increases the quantum bit error rate measured under the after-gate attack above the typical QKD security threshold, thus favouring the detector's inherent security. This represents a significant step to avert quantum hacking of QKD systems.

Description

Keywords

5108 Quantum Physics, 5102 Atomic, Molecular and Optical Physics, 51 Physical Sciences

Journal Title

Physical Review Applied

Conference Name

Journal ISSN

2331-7019
2331-7019

Volume Title

12

Publisher

American Physical Society (APS)

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (1678703)