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The Differential-Phase-Shift (DPS) and the Coherent-One-Way (COW) are among the most practical protocols for quantum cryptography, and are therefore the object of fast-paced experimental developments. The assessment of their security is…

Quantum Physics · Physics 2010-11-04 Cyril Branciard , Nicolas Gisin , Valerio Scarani

Quantum networks are complex systems formed by the interaction among quantum processors through quantum channels. Analogous to classical computer networks, quantum networks allow for the distribution of quantum computation among quantum…

Quantum Physics · Physics 2021-11-08 Matheus Guedes de Andrade , Wenhan Dai , Saikat Guha , Don Towsley

The study of quantum walk processes has been widely divided into two standard variants, the discrete-time quantum walk (DTQW) and the continuous-time quantum walk (CTQW). The connection between the two variants has been established by…

Quantum Physics · Physics 2008-11-08 C. M. Chandrashekar

This manuscript gathers and subsumes a long series of works on using QW to simulate transport phenomena. Quantum Walks (QWs) consist of single and isolated quantum systems, evolving in discrete or continuous time steps according to a…

Quantum Physics · Physics 2021-12-23 Giuseppe Di Molfetta

Quantum walks in atomic systems, owing to their continuous nature, are especially well-suited for the simulation of many-body physics and can potentially offer an exponential speedup in solving certain black box problems. Photonics offers…

The evolution of a walker in standard "Discrete-time Quantum Walk (DTQW)" is determined by coin and shift unitary operators. The conditional shift operator shifts the position of the walker to right or left by unit step size while the…

Quantum Physics · Physics 2020-03-03 Rashid Ahmad , Safia Bibi , Uzma Sajjad

Quantum repeaters create long-distance entanglement between quantum systems while overcoming difficulties such as the attenuation of single photons in a fiber. Recently, an implementation of a repeater protocol based on single qubits in…

Quantum Physics · Physics 2007-07-03 L. Jiang , J. M. Taylor , M. D. Lukin

Quantum Key Distribution (QKD) is an emerging cryptographic method designed for secure key sharing. Its security is theoretically guaranteed by fundamental principles of quantum mechanics, making it a leading candidate for future…

Quantum Physics · Physics 2025-12-03 Chia-Tso Lai

In this work, we present a new model of the Discrete-Time Open Quantum Walk (DTOQW) applicable to an arbitrary graph, thereby going beyond the case of quantum walks on regular graphs. We study the impact of noise in the dynamics of quantum…

Quantum Physics · Physics 2025-06-03 Monika Rani , Supriyo Dutta , Subhashish Banerjee

In this paper, we consider continuous-time quantum walks (CTQWs) on one-dimension ring lattice of N nodes in which every node is connected to its 2m nearest neighbors (m on either side). In the framework of the Bloch function ansatz, we…

Quantum Physics · Physics 2009-11-13 Xinping Xu , Feng Liu

Discrete-time quantum walks (DTQWs) in random artificial electric and gravitational fields are studied analytically and numerically. The analytical computations are carried by a new method which allows a direct exact analytical…

Quantum Physics · Physics 2017-04-25 G. Di Molfetta , F. Debbasch

In this paper, we study the recurrence of Open Quantum Walks induced by finite-dimensional coins on the line ($\mathbb{Z}$) and on the grid ($\mathbb{Z}^2$). Two versions are considered: discrete-time open quantum walks (OQW) and…

Quantum Physics · Physics 2026-03-23 Newton Loebens

In recent years, several properties and recurrence criteria of discrete-time open quantum walks (OQWs) have been presented. Recently, Pellegrini introduced continuous-time open quantum walks (CTOQWs) as continuous-time natural limits of…

Quantum Physics · Physics 2023-06-01 Newton Loebens

Quantum walks have been employed widely to develop new tools for quantum information processing recently. A natural quantum walk dynamics of interacting particles can be used to implement efficiently the universal quantum computation. In…

Quantum Physics · Physics 2016-10-04 Alexey A. Melnikov , Leonid E. Fedichkin

We present a scheme for quantum secure direct communication with quantum encryption. The two authorized users use repeatedly a sequence of the pure entangled pairs (quantum key) shared for encrypting and decrypting the secret message…

Quantum Physics · Physics 2007-07-31 Xi-Han Li , Chun-Yan Li , Fu-Guo Deng , Ping Zhou , Yu-Jie Liang , Hong-Yu Zhou

Quantum walk (QW) provides a versatile tool to study fundamental physics and also to make a variety of practical applications. We here start with the recent idea of {\it nonlinear} QW and show that introducing {\it nonlinearity} to QW can…

Quantum Physics · Physics 2015-12-29 Chang-Woo Lee , Paweł Kurzyński , Hyunchul Nha

Quantum secure direct communication (QSDC) can directly transmit secrete messages through quantum channel. Device-independent (DI) QSDC can guarantee the communication security relying only on the observation of the Bell inequality…

Quantum Physics · Physics 2023-03-29 Lan Zhou , Bao-Wen Xu , Wei Zhong , Yu-Bo Sheng

Distributing arbitrary graph states across quantum networks is a central challenge for modular quantum computing and measurement-based quantum communication. We introduce the phase quantum walk (PQW), a discrete-time quantum walk in which…

Quantum Physics · Physics 2026-05-19 Soumyojyoti Dutta

The discrete time quantum walk (DTQW) is a universal quantum computational model. Significant relationships between discrete and corresponding continuous quantum systems have been studied since the work of Pauli and Feynman. This work…

Quantum Physics · Physics 2019-09-19 Michael Manighalam , Mark Kon

Quantum communication holds promise for absolutely security in secret message transmission. Quantum secure direct communication is an important mode of the quantum communication in which secret messages are securely communicated over a…

Quantum Physics · Physics 2015-09-08 Jianyong Hu , Bo Yu , Mingyong Jing , Liantuan Xiao , Suotang Jia , Guoqing Qin , Guilu Long