Experimental demonstration of intensity-modulation/direct-detection secret key distribution

Traditionally, the study of quantum key distribution (QKD) assumes an omnipotent eavesdropper that is only limited by the laws of physics. However, this is not the case for specific application scenarios such as the QKD over a free-space link. In this invited paper, we introduce the geometrical optics restricted eavesdropping model for secret key distillation security analysis and apply to a few scenarios common in satellite-to-satellite applications.

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Experimental demonstrations of unconditional security in a purely classical regime

Scientific Reports ◽

10.1038/s41598-021-83724-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Byoung S. Ham

Keyword(s):

Quantum Key Distribution ◽

Key Distribution ◽

Unconditional Security ◽

Zehnder Interferometer ◽

Experimental Demonstration ◽

Orthogonal Bases ◽

Unitary Transformations ◽

Mach Zehnder Interferometer

AbstractSo far, unconditional security in key distribution processes has been confined to quantum key distribution (QKD) protocols based on the no-cloning theorem of nonorthogonal bases. Recently, a completely different approach, the unconditionally secured classical key distribution (USCKD), has been proposed for unconditional security in the purely classical regime. Unlike QKD, both classical channels and orthogonal bases are key ingredients in USCKD, where unconditional security is provided by deterministic randomness via path superposition-based reversible unitary transformations in a coupled Mach–Zehnder interferometer. Here, the first experimental demonstration of the USCKD protocol is presented.

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A novel error correction protocol for continuous variable quantum key distribution

Scientific Reports ◽

10.1038/s41598-021-90055-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kadir Gümüş ◽

Tobias A. Eriksson ◽

Masahiro Takeoka ◽

Mikio Fujiwara ◽

Masahide Sasaki ◽

...

Keyword(s):

Error Correction ◽

Quantum Key Distribution ◽

Ldpc Codes ◽

Key Distribution ◽

Continuous Variable ◽

Early Termination ◽

Parity Check ◽

Secret Key ◽

Ldpc Decoder ◽

And Performance

AbstractReconciliation is a key element of continuous-variable quantum key distribution (CV-QKD) protocols, affecting both the complexity and performance of the entire system. During the reconciliation protocol, error correction is typically performed using low-density parity-check (LDPC) codes with a single decoding attempt. In this paper, we propose a modification to a conventional reconciliation protocol used in four-state protocol CV-QKD systems called the multiple decoding attempts (MDA) protocol. MDA uses multiple decoding attempts with LDPC codes, each attempt having fewer decoding iteration than the conventional protocol. Between each decoding attempt we propose to reveal information bits, which effectively lowers the code rate. MDA is shown to outperform the conventional protocol in regards to the secret key rate (SKR). A 10% decrease in frame error rate and an 8.5% increase in SKR are reported in this paper. A simple early termination for the LDPC decoder is also proposed and implemented. With early termination, MDA has decoding complexity similar to the conventional protocol while having an improved SKR.

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Security Analysis of Discrete-Modulated Continuous-Variable Quantum Key Distribution over Seawater Channel

Applied Sciences ◽

10.3390/app9224956 ◽

2019 ◽

Vol 9 (22) ◽

pp. 4956 ◽

Cited By ~ 2

Author(s):

Xinchao Ruan ◽

Hang Zhang ◽

Wei Zhao ◽

Xiaoxue Wang ◽

Xuan Li ◽

...

Keyword(s):

Quantum Key Distribution ◽

Secure Communication ◽

Security Analysis ◽

Finite Size ◽

Key Distribution ◽

Continuous Variable ◽

Heterodyne Detection ◽

Secret Key ◽

Transmission Distance ◽

Better Than

We investigate the optical absorption and scattering properties of four different kinds of seawater as the quantum channel. The models of discrete-modulated continuous-variable quantum key distribution (CV-QKD) in free-space seawater channel are briefly described, and the performance of the four-state protocol and the eight-state protocol in asymptotic and finite-size cases is analyzed in detail. Simulation results illustrate that the more complex is the seawater composition, the worse is the performance of the protocol. For different types of seawater channels, we can improve the performance of the protocol by selecting different optimal modulation variances and controlling the extra noise on the channel. Besides, we can find that the performance of the eight-state protocol is better than that of the four-state protocol, and there is little difference between homodyne detection and heterodyne detection. Although the secret key rate of the protocol that we propose is still relatively low and the maximum transmission distance is only a few hundred meters, the research on CV-QKD over the seawater channel is of great significance, which provides a new idea for the construction of global secure communication network.

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