Sending or Not-Sending Twin-Field Quantum Key Distribution with Flawed and Leaky Sources

Abstract

Twin-field quantum key distribution (TF-QKD) has attracted considerable attention and developed rapidly due to its ability to surpass the fundamental rate-distance limit of QKD. However, the device imperfections may compromise its practical implementations. The goal of this paper is to make it robust against the state preparation flaws (SPFs) and side channels at the light source. We adopt the sending or not-sending (SNS) TF-QKD protocol to accommodate the SPFs and multiple optical modes in the emitted states. We analyze that the flaws of the phase modulation can be overcome by regarding the deviation of the phase as phase noise and eliminating it with the post-selection of phase. To overcome the side channels, we extend the generalized loss-tolerant (GLT) method to the four-intensity decoy-state SNS protocol. Remarkably, by decomposing of the two-mode single-photon states, the phase error rate can be estimated with only four parameters. The practical security of the SNS protocol with flawed and leaky source can be guaranteed. Our results might constitute a crucial step towards guaranteeing the practical implementation of the SNS protocol.

Security Analysis of Sending or Not-Sending Twin-Field Quantum Key Distribution with Weak Randomness

“…Particularly, the sending-or-not-sending (SNS) TF-QKD [ 12 ], as an efficient protocol, can tolerate large misalignment errors even up to in the single-photon interference. In fact, the SNS TF-QKD protocol has made significant progress in theory [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. In addition, several experiments on the SNS protocol have also been performed so far [ 26 , 27 , 28 , 29 , 30 , 31 ].…”

Phase-matching quantum key distribution with imperfect sources

“…In recent years, QKD has made tremendous progress, which includes the realization of longdistance fiber communication systems [1][2][3][4][5][6][7][8][9][10][11] and the deployment of QKD networks. [12][13][14][15] Although the theoretical assumptions of QKD are impeccable, the actual devices have potential security loopholes, [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] which seriously threaten the security of QKD.…”

“…For the THAs, when Eve injects strong light into Alice and Bob, information leakage can be detected by observing back-reflected light. For both the PMDs and THAs, the state may not be a qubit, the generalized LT (GLT) protocol can solve this problem, [24,25] but the GLT protocol is more complex and requires a lot of calculations. The existing security analysis assumes that the state is independent and identically distributed.…”

Multi-Party Quantum Private Comparison Based on Bell States

“…In 1984, Bennett and Brassard [ 2 ] amalgamated the principles of quantum mechanics with classical cryptography, thus presenting the pioneering quantum cryptography protocol. Subsequently, a multitude of quantum cryptography protocols have been put forward, which encompass quantum secret sharing (QSS) [ 3 , 4 ], quantum key distribution (QKD) [ 2 , 5 , 6 , 7 , 8 , 9 , 10 ], quantum private query (QPQ) [ 11 , 12 ], quantum-secure direct communication (QSDC) [ 13 , 14 ], and various others.…”