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This study proposes a framework for incorporating wavenumber-domain acoustic reflection coefficients into sound field analysis to characterize direction-dependent material reflection and scattering phenomena. The reflection coefficient is…

Audio and Speech Processing · Electrical Eng. & Systems 2026-01-13 Satoshi Hoshika , Takahiro Iwami , Akira Omoto

With the rise of quantum technologies, data security increasingly relies on quantum cryptography and its most notable application, quantum key distribution (QKD). Yet, current technological limitations, in particular, the unavailability of…

Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase…

Quantum key distribution (QKD) establishes secure links between remote communication parties. As a key problem for various QKD protocols, security analysis gives the amount of secure keys regardless of the eavesdropper's computational…

Quantum Physics · Physics 2023-09-26 Hongyi Zhou , Toshihiko Sasaki , Masato Koashi

We report the distribution of a cryptographic key, secure from photon number splitting attacks, over 35 km of optical fiber using single photons from an InAs quantum dot emitting ~1.3 microns in a pillar microcavity. Using below…

Quantum Physics · Physics 2007-11-08 P. M. Intallura , M. B. Ward , O. Z. Karimov , Z. L. Yuan , P. See , A. J. Shields , P. Atkinson , D. A. Ritchie

Optical fibres constitute an exceptional sensing platform. However, standard fibres present an inherent sensing challenge: they confine light by design to an inner core. Consequently, nearly all distributed fibre sensors are restricted to…

Optics · Physics 2018-11-21 Gil Bashan , Hilel Hagai Diamandi , Yosef London , Eyal Preter , Avi Zadok

In distributed fiber-optic sensing based on optical frequency domain reflectometry (OFDR), Doppler frequency shifts due to the changes of disturbances during one sweep period introduce demodulation errors that accumulate along both the…

Optics · Physics 2024-10-28 Qiang Yang , Weilin Xie , Congfan Wang , Bowen Li , Xin Li , Xiang Zheng , Wei Wei , Yi Dong

Quantum key distribution (QKD) is a key application in quantum communication, enabling secure key exchange between parties using quantum states. Twin-field (TF) QKD offers a promising solution that surpasses the repeaterless limits, and its…

Quantum Physics · Physics 2025-05-28 Chunfeng Huang , Rui Guan , Xin Liu , Wenjie He , Shizhuo Li , Hao Liang , Ziyang Luo , Zhenrong Zhang , Wei Li , Kejin Wei

Quantum key distribution (QKD) promises provably secure communications. In order to improve the secret key rate, combining a biased basis choice with the decoy-state method is proposed. Concomitantly, there is a basis-independent detection…

Quantum Physics · Physics 2021-08-11 Hua-Lei Yin , Peng Liu , Wei-Wei Dai , Zhao-Hui Ci , Jie Gu , Tian Gao , Qiang-Wei Wang , Zi-Yao Shen

Many papers proved the security of quantum key distribution (QKD) system, in the asymptotic framework. The degree of the security has not been discussed in the finite coding-length framework, sufficiently. However, to guarantee any…

Quantum Physics · Physics 2009-11-13 Masahito Hayashi

Quantum key distribution (QKD) offers a reliable solution to communication problems that require long-term data security. For its widespread use, however, the rate and reach of QKD systems must be improved. Twin-field (TF) QKD is a step…

Quantum key distribution (QKD) protocols are proven secure based on fundamental physical laws, however, the proofs consider a well-defined setting and encoding of the sent quantum signals only. Side channels, where the encoded quantum state…

We propose a new quantum key distribution (QKD) protocol based on the fully quantum mechanical states of the Faraday rotators. The protocol is unconditionally secure against collective attacks for multi-photon source up to two photons on a…

Quantum Physics · Physics 2008-09-24 Taeseung Choi , Mahn-Soo Choi

We propose a novel continuous-variable quantum key distribution (CVQKD) protocol that employs orthogonal frequency-division multiplexing (OFDM) in the terahertz (THz) band to enable high-throughput and secure quantum communication. By…

Quantum Physics · Physics 2025-07-01 Mingqi Zhang , Kaveh Delfanazari

The appropriate selection of recurrence thresholds is a key problem in applications of recurrence quantification analysis (RQA) and related methods across disciplines. Here, we discuss the distribution of pairwise distances between state…

Data Analysis, Statistics and Probability · Physics 2018-04-11 K. Hauke Krämer , Reik V. Donner , Jobst Heitzig , Norbert Marwan

Laser with high spectral purity plays a crucial role in high-precision optical metrology and coherent communication. Thanks to the rapid development of laser frequency stabilization, the laser phase noise can be remarkably compensated,…

Instrumentation and Detectors · Physics 2020-04-22 Liang Zhang , Liang Chen , Xiaoyi Bao

We present a 625 MHz clocked coherent one-way quantum key distribution (QKD) system which continuously distributes secret keys over an optical fibre link. To support high secret key rates, we implemented a fast hardware key distillation…

Quantum key distribution (QKD) promises information-theoretic security based on quantum mechanics, but practical implementations face security vulnerabilities due to device imperfections. Recent advances have separately addressed source and…

Quantum Physics · Physics 2025-07-08 Guillermo Currás-Lorenzo , Margarida Pereira , Shlok Nahar , Devashish Tupkary

We experimentally demonstrated a sub-Mbps key rate Gaussian-modulated coherent-state continuous-variable quantum key distribution (CV-QKD) over 100 km transmission distance. To efficiently control the excess noise, the quantum signal and…

Quantum Physics · Physics 2023-04-12 Yaodi Pi , Heng Wang , Yan Pan , Yun Shao , Yang Li , Jie Yang , Yichen Zhang , Wei Huang , Bingjie Xu

Quantum key distribution (QKD) enables unconditionally secure symmetric key exchange between parties. However, terrestrial fibre-optic links face inherent distance constraints due to quantum signal degradation. Traditional solutions to…

Cryptography and Security · Computer Science 2026-03-10 Aitor Brazaola-Vicario , Oscar Lage , Julen Bernabé-Rodríguez , Eduardo Jacob , Jasone Astorga