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A long-standing problem in quantum physics is to determine the minimal number of measurement bases required for the complete characterization of unknown quantum states, a question of particular relevance to high-dimensional quantum…

Quantum Physics · Physics 2025-08-12 Tianqi Xiao , Yaxin Wang , Ying Xia , Zhihao Li , Xiaoqi Zhou

We describe two procedures which, given access to one copy of a quantum state and a sequence of two-outcome measurements, can distinguish between the case that at least one of the measurements accepts the state with high probability, and…

Quantum Physics · Physics 2017-04-18 Aram W. Harrow , Cedric Yen-Yu Lin , Ashley Montanaro

In recent years, several measures have been proposed for characterizing the coherence of a given quantum state. We derive several results that illuminate how these measures behave when restricted to pure states. Notably, we present an…

Quantum Physics · Physics 2016-10-26 Jianxin Chen , Shane Grogan , Nathaniel Johnston , Chi-Kwong Li , Sarah Plosker

Entangled states in high dimensional systems are of great interest due to the extended possibilities they provide in quantum information processing. Recently, Sun et al. [Phys. Rev. A 82, 052323 (2010)] and Kim et al. [Nat. Phys. 8, 117…

Quantum Physics · Physics 2017-07-03 Xing Xiao , Yan-Ling Li

In this paper we consider the purification of a quantum state using the information obtained from a continuous measurement record, where the classical measurement record is digitized to a single bit per measurement after the measurements…

Quantum Physics · Physics 2012-01-05 Jason F. Ralph , Neil P. Oxtoby

The accurate characterization of quantum systems is essential for the advancement of quantum technologies. In particular, certifying convex functions of quantum states plays a central role in many applications. We present a certification…

Quantum Physics · Physics 2026-01-26 Leonardo Zambrano , Teodor Parella-Dilmé , Antonio Acín , Donato Farina

We review and discuss the potential of using measurement-based elements in quantum communication schemes, where certain tasks are realized with the help of entangled resource states that are processed by measurements. We consider long-range…

Quantum Physics · Physics 2016-09-27 M. Zwerger , H. J. Briegel , W. Dür

Entanglement-measurement attack is one of the most famous attacks against quantum cryptography. In quantum cryptography protocols, eavesdropping checking is an effective means to resist this attack. There are currently two commonly used…

Quantum Physics · Physics 2026-01-09 Zhaoxu Ji , Huanguo Zhang

We introduce an operational and statistically meaningful measure, the quantum tomographic transfer function, that possesses important physical invariance properties for judging whether a given informationally complete quantum measurement…

Quantum Physics · Physics 2019-07-31 Jaroslav Rehacek , Yong Siah Teo , Zdenek Hradil

Mutually unbiased bases determine an optimal set of measurements to extract complete information about the quantum state of a system. However, quite often a priori information about the state exist, making some of the measurement bases…

Quantum Physics · Physics 2015-06-12 A. B. Klimov , G. Bjork , L. L. Sanchez-Soto

This document focuses on translating various information-theoretic measures of distinguishability for probability distributions into measures of distin- guishability for quantum states. These measures should have important appli- cations in…

Quantum Physics · Physics 2007-05-23 Christopher A. Fuchs

The optimal quantum measurements for estimating different unknown parameters in a parameterized quantum state are usually incompatible with each other. Traditional approaches to addressing the measurement incompatibility issue, such as the…

Quantum Physics · Physics 2026-02-03 Sisi Zhou , Senrui Chen

We demonstrate in a superconducting qubit the conditional recovery ("uncollapsing") of a quantum state after a partial-collapse measurement. A weak measurement extracts information and results in a non-unitary transformation of the qubit…

Quantum measurements not only extract information from a system but also alter its state. Although the outcome of the measurement is probabilistic, the backaction imparted on the measured system is accurately described by quantum theory.…

Quantum Physics · Physics 2014-04-21 M. S. Blok , C. Bonato , M. L. Markham , D. J. Twitchen , V. V. Dobrovitski , R. Hanson

Quantum measurement is essential to both the foundations and practical applications of quantum information science. Among many possible models of quantum measurement, feedback measurements that dynamically update their physical structure…

Quantum Physics · Physics 2020-02-25 Shuro Izumi , Jonas S. Neergaard-Nielsen , Ulrik L. Andersen

Quantum tomography is the main method used to assess the quality of quantum information processing devices, but its complexity presents a major obstacle for the characterization of even moderately large systems. The number of experimental…

Quantum Physics · Physics 2015-03-19 Marcus P. da Silva , Olivier Landon-Cardinal , David Poulin

The determination of the quantum state of a single system by protective observation is used to justify operationally a formulation of quantum theory on the quantum state space (projective Hilbert space) $\cal P$. Protective observation is…

General Relativity and Quantum Cosmology · Physics 2007-05-23 J. Anandan

State disturbance by a quantum measurement is at the core of foundational quantum physics and constitutes a fundamental basis of secure quantum information processing. While quantifying an information-disturbance relation has been a…

Quantum Physics · Physics 2022-02-07 Seongjin Hong , Yong-Su Kim , Young-Wook Cho , Jaewan Kim , Seung-Woo Lee , Hyang-Tag Lim

Low-capacitance Josephson junction systems as well as coupled quantum dots, in a parameter range where single charges can be controlled, provide physical realizations of quantum bits, discussed in connection with quantum computing. The…

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

We propose two experimental schemes for quantum state discrimination that achieve the optimal tradeoff between the probability of correct identification and the disturbance on the quantum state.

Quantum Physics · Physics 2007-05-23 Francesco Buscemi , Massimiliano F. Sacchi