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The certification of entanglement dimensionality is of great importance in characterizing quantum systems. Recently, it is pointed out that quantum correlation of high-dimensional states can be simulated with a sequence of lower-dimensional…

Quantum Physics · Physics 2020-06-22 Yu Guo , Bai-Chu Yu , Xiao-Min Hu , Bi-Heng Liu , Yu-Chun Wu , Yun-Feng Huang , Chuan-Feng Li , Guang-Can Guo

Unsharp measurements are increasingly important for foundational insights in quantum theory and quantum information applications. Here, we report an experimental implementation of unsharp qubit measurements in a sequential communication…

By testing the classical correlation violation between two systems, the random number can be expanded and certified without applying classical statistical method. In this work, we propose a new random number expansion protocol without…

Quantum Physics · Physics 2011-12-21 Hong-Wei Li , Zhen-Qiang Yin , Yu-Chun Wu , Xu-Bo Zou , Shuang Wang , Wei Chen , Guang-Can Guo , Zheng-Fu Han

We consider a non-contextual inequality in the sequential measurement scenario and derive the optimal quantum violation of it without assuming the dimension of the system. Since the measurement is dichotomic and the dimension of the quantum…

Quantum Physics · Physics 2026-03-30 Ritwija Roy , Anindya Biswas

We introduce a framework to compute upper bounds for temporal correlations achievable in open quantum system dynamics, obtained by repeated measurements on the system. As these correlations arise by virtue of the environment acting as a…

Quantum Physics · Physics 2024-01-17 Lucas B. Vieira , Simon Milz , Giuseppe Vitagliano , Costantino Budroni

In this article we present a new prepare and measure quantum key distribution protocol that decouples the necessary quantum channel error estimation from its dependency on sifting, or otherwise post-selecting, the detection outcomes. Rather…

Quantum Physics · Physics 2017-02-27 James E. Troupe , Jacob M. Farinholt

Quantum incompatibility, referred as the phenomenon that some quantum measurements cannot be performed simultaneously, is necessary for various quantum information processing tasks, such as nonlocality and steering. When these applications…

Quantum Physics · Physics 2024-11-19 Xiaolin Zhang , Rui Qu , Zehong Chang , Yunlong Wang , Zhenyu Guo , Min An , Hong Gao , Fuli Li , Pei Zhang

We report on a new class of dimension witnesses, based on quantum random access codes, which are a function of the recorded statistics and that have different bounds for all possible decompositions of a high-dimensional physical system.…

We show that the phenomenon of quantum contextuality can be used to certify lower bounds on the dimension accessed by the measurement devices. To prove this, we derive bounds for different dimensions and scenarios of the simplest…

Quantum Physics · Physics 2014-06-12 Otfried Gühne , Costantino Budroni , Adan Cabello , Matthias Kleinmann , Jan-Åke Larsson

Quantum Darwinism is a compelling theory that describes the quantum-to classical transition as the emergence of objectivity of quantum systems. Spectrum broadcast structure and strong quantum Darwinism are two extensions of this theory with…

Quantum Physics · Physics 2020-10-21 Thao P. Le , Alexandra Olaya-Castro

The fact that not all quantum observables are jointly measurable is one of the major differences between quantum and classical theory. In the former, non-commuting observables can only be simultaneously measured with limited precision. We…

Quantum Physics · Physics 2016-10-17 Gilles Pütz , Tomer Barnea , Nicolas Gisin , Anthony Martin

Bipartite Bell inequalities can be simultaneously violated by two different pairs of observers when weak measurements and signaling is employed. Here we experimentally demonstrate the violation of two simultaneous CHSH inequalities by…

Quantum Physics · Physics 2017-04-10 Matteo Schiavon , Luca Calderaro , Mirko Pittaluga , Giuseppe Vallone , Paolo Villoresi

Entanglement detection is a fundamental task in quantum information science, serving as a cornerstone for quantum benchmarking and foundational studies. With an increasing qubit number that can be effectively controlled, there is a pressing…

Weak measurement of a quantum system followed by postselection based on a subsequent strong measurement gives rise to a quantity called the weak value: a complex number for which the interpretation has long been debated. We analyse the…

Quantum Physics · Physics 2015-07-16 Angela Karanjai , Eric G. Cavalcanti , Stephen D. Bartlett , Terry Rudolph

This work will incorporate a few related tools for addressing the conceptual difficulties arising from sewing together classical and quantum mechanics: deterministic operators, weak measurements and post-selection. Weak Measurement, based…

Quantum Physics · Physics 2016-12-21 Eliahu Cohen , Yakir Aharonov

We consider highly inaccurate measurements made on classical stochastic and quantum systems. In the quantum case such a \e{weak} measurement preserves coherence between the system's alternatives. We demonstrate that in both cases the…

Quantum Physics · Physics 2026-03-16 D. Sokolovski , D. Alonso , S. Brouard

Based on a sequential communication game, semi-device independent certification of an unsharp instrument has recently been demonstrated [\href{https://iopscience.iop.org/article/10.1088/1367-2630/ab3773}{New J. Phys. 21 083034 (2019),…

Quantum Physics · Physics 2021-12-30 Sumit Mukherjee , A. K. Pan

A fundamental resource in any communication and computation task is the amount of information that can be transmitted and processed. Information encoded in a classical system is limited by the dimension d_c of the system, i.e., the number…

Quantum Physics · Physics 2013-01-16 Johan Ahrens , Piotr Badziag , Adan Cabello , Mohamed Bourennane

We study the relation between semi and fully device independent protocols. As a tool, we use the correspondence between Bell inequalities and dimension witnesses. We present a method for converting the former into the latter and vice versa.…

We exploit quantum discord (and geometric discord) to detect quantum correlations present in a well-known communication model called quantum random access codes (QRACs), which has a variety of applications in areas ranging form quantum…