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Quantum measurements are not deterministic. For this reason quantum measurements are repeated for a number of shots on identically prepared systems. The uncertainty in each measurement depends on the number of shots and the expected outcome…

Quantum Physics · Physics 2025-03-12 Pieter Thijs Eendebak

Measuring the state of quantum computers is a highly non-trivial task, with implications for virtually all quantum algorithms. We propose a novel scheme where identical copies of a quantum state are measured jointly so that all Pauli…

Quantum Physics · Physics 2025-09-03 Rick P. A. Simon , Zheng Shi , Charlie Nation , Andrew Jena , Luca Dellantonio

Quantum capacity quantifies the amount of quantum information that can be transmitted by a quantum channel with an arbitrary small probability of error. Mathematically, the quantum capacity is given by an asymptotic formula involving the…

Quantum Physics · Physics 2025-12-30 Zhen Wu , Zhihao Ma , James Fullwood

Stochastic processes underlie a vast range of natural and social phenomena. Some processes such as atomic decay feature intrinsic randomness, whereas other complex processes, e.g. traffic congestion, are effectively probabilistic because we…

Analyzing carefully an experimentally feasible non-entangled single qubit quantum secret sharing protocol and its modified version [Phys. Rev. Lett. 95, 230505 (2005); ibid. 98, 028902 (2007)], it is found that both versions are insecure…

Quantum Physics · Physics 2011-03-07 Guang Ping He , Z. D. Wang

In this article, we introduce a quantum key distribution protocol for the line of sight channels based on coincidence measurements. We present a proof-of-concept implementation of our protocol. We show that using coincidence measurements to…

When measuring phase of quantum states of light, the optimal single-shot measurement implements projection on the un-physical phase states. If we want to improve the precision further we need to accept a reduced probability of success,…

Quantum Physics · Physics 2015-06-16 Petr Marek

Several techniques of generating random quantum channels, which act on the set of $d$-dimensional quantum states, are investigated. We present three approaches to the problem of sampling of quantum channels and show under which conditions…

Quantum Physics · Physics 2021-06-16 Ryszard Kukulski , Ion Nechita , Łukasz Pawela , Zbigniew Puchała , Karol Życzkowski

The quantum measurement process by a single-electron transistor or a quantum point contact coupled to a quantum bit is studied. We find a unified description of the statistics of the monitored quantity, the current, in the regime of strong…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yuriy Makhlin , Gerd Schoen , Alexander Shnirman

We analyse the benefit, in terms of extracting work, of having a single use of a quantum channel or measurement in quantum thermodynamics. This highlights a connection between unital and catalytic channels, and some subtleties concerning…

Quantum Physics · Physics 2021-07-21 Tom Purves , Tony Short

We develop two general approaches to characterising the manipulation of quantum states by means of probabilistic protocols constrained by the limitations of some quantum resource theory. First, we give a general necessary condition for the…

Quantum Physics · Physics 2023-06-23 Bartosz Regula

The ability to transfer coherent quantum information between systems is a fundamental component of quantum technologies and leads to coherent correlations within the global quantum process. However correlation structures in quantum channels…

Quantum Physics · Physics 2022-05-03 Matthew Girling , Cristina Cirstoiu , David Jennings

We compare schemes for testing whether two parties share a two-qubit singlet state. The first, standard, scheme tests Braunstein-Caves (or CHSH) inequalities, comparing the correlations of local measurements drawn from a fixed finite set…

Quantum Physics · Physics 2025-05-13 George Cowperthwaite , Adrian Kent

Randomized algorithms are crucial subroutines in quantum computing, but the requirement to execute many types of circuits on a real quantum device has been challenging to their extensive implementation. In this study, we propose an…

Quantum Physics · Physics 2026-04-23 Shu Kanno , Ikko Hamamura , Rudy Raymond , Qi Gao , Naoki Yamamoto

Two qubit operation sharing schemes [J. Phys. B 44 (2011) 165508] are generalized to qutrit ones. Operations to be shared are classified into three different classes in terms of different probabilities (i.e, 1/3, 2/3 and 1). For the latter…

Quantum Physics · Physics 2013-04-30 Daochu Liu , Yimin Liu , Xiaofeng Yin , Xiansong Liu , Zhanjun Zhang

Exploring the symmetries underlying a previously proposed encryption scheme which relies on single-qubit rotations, we derive an improved upper bound on the maximum information that an eavesdropper might extract from all the available…

Quantum Physics · Physics 2012-03-02 U. Seyfarth , G. M. Nikolopoulos , G. Alber

Universal control of quantum systems is a major goal to be achieved for quantum information processing, which demands thorough understanding of fundamental quantum mechanics and promises applications of quantum technologies. So far, most…

Quantum Physics · Physics 2019-02-05 Ling Hu , Xianghao Mu , Weizhou Cai , Yuwei Ma , Yuan Xu , Haiyan Wang , YiPu Song , Chang-Ling Zou , Luyan Sun

We formulate minimum-error and unambiguous discrimination problems for quantum processes in the language of process positive operator valued measures (PPOVM). In this framework we present the known solution for minimum-error discrimination…

Quantum Physics · Physics 2015-05-18 Mario Ziman , Michal Sedlák

Randomized measurements are useful for analyzing quantum systems especially when quantum control is not fully perfect. However, their practical realization typically requires multiple rotations in the complex space due to the adoption of…

Quantum Physics · Physics 2025-08-28 Jin-Min Liang , Satoya Imai , Shuheng Liu , Shao-Ming Fei , Otfried Gühne , Qiongyi He

Two tripartite schemes are put forward with shared entanglements and LOCC for sharing an operation on a remote target sate. The first scheme uses a Bell and a symmetric W states as quantum channels, while the second replaces the symmetric W…

Quantum Physics · Physics 2013-04-30 Qibin Jia , Yimin Liub , Xiansong Liua , Xiaofeng Yina , Zhanjun Zhang