Improving continuous-variable quantum key distribution under local oscillator intensity attack using entanglement in the middle

Abstract

A modified continuous-variable quantum key distribution (CVQKD) protocol is proposed by originating the entangled source from a malicious third party Eve in the middle instead of generating it from the trustworthy Alice or Bob. This method is able to enhance the efficiency of the CVQKD scheme attacked by local oscillator (LO) intensity attack in terms of the generated secret key rate in quantum communication. The other indication of the improvement is that the maximum transmission distance and the maximum loss tolerance can be increased significantly, especially for CVQKD schemes based on homodyne detection.

Noiseless linear amplification for the single-photon entanglement of arbitrary polarization–time-bin qudit

“…In the past few decades, entanglement has been widely used in quantum teleportation, [1][2][3][4] quantum secure direct communication, [5][6][7][8][9][10][11][12] quantum key distribution, [13][14][15][16] and so on. [17][18][19][20][21][22][23][24] Among the various entanglement forms, single-photon entanglement (SPE) with the form of (|1 A 0 B + |0 A 1 B )/ √ 2 (A and B are two distant locations) is the simplest but most important entanglement mode. SPE has important applications in cryptography [25,26] and quantum repeater protocols.…”

Four-State Modulation in Middle of a Quantum Channel for Continuous-Variable Quantum Key Distribution Protocol with Noiseless Linear Amplifier*

“…The scheme of the four-state CV-QKD protocol with an untrusted source in the middle can be described with two steps. [25] First, the untrusted third party, Charlie encodes information in the quadratures of two-mode coherent states, and then he sends one of the four-state to Alice and Bob respectively with equal probability through unsecure channels 1 and 2 which could completely controlled by the eavesdropper, and Eve may perform her attack. Then Alice and Bob perform either homodyne (Hom) or heterodyne (Het) detection on the received modes 𝐴 2 and 𝐵 2 .…”