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It is proposed that measurement devices can be modelled to have an open decoherence dynamics that is faster than any other relevant timescale, which is referred to as the ultradecoherence limit. In this limit, the measurement device always…

Quantum Physics · Physics 2025-06-09 Hai-Chau Nguyen

Recently, a basis-invariant measure of coherence known as the intrinsic degree of coherence has been established for classical and single-particle quantum states [JOSA B {\bf 36}, 2765 (2019)]. Using the same mathematical construction, in…

Quantum Physics · Physics 2020-03-30 Nilakantha Meher , Abu Saleh Musa Patoary , Girish Kulkarni , Anand K. Jha

Decoherence in nearly-isolated GaAs quantum dots is investigated using the change in average Coulomb blockade peak height upon breaking time-reversal symmetry. The normalized change in average peak height approaches the predicted universal…

Mesoscale and Nanoscale Physics · Physics 2012-11-19 J. A. Folk , C. M. Marcus , J. S. Harris

Although the solution, within standard quantum physics, of the problem of outcomes has been published several times, many authors continue to treat measurement as an unsolved fundamental dilemma. The solution lies in the formation of…

Quantum Physics · Physics 2022-06-14 Art Hobson

Consider a joint quantum state of a system and its environment. A measurement on the environment induces a decomposition of the system state. Using algorithmic information theory, we define the preparation information of a pure or mixed…

Quantum Physics · Physics 2015-06-26 Andrei N. Soklakov , Ruediger Schack

Coherence in an open quantum system is degraded through its interaction with a bath. This decoherence can be avoided by restricting the dynamics of the system to special decoherence-free subspaces. These subspaces are usually constructed…

Quantum Physics · Physics 2016-09-08 Daniel A. Lidar , Dave Bacon , Julia Kempe , K. B. Whaley

The problem investigated in this paper is einselection, i. e. the selection of mutually exclusive quantum states with definite probabilities through decoherence. Its study is based on a theory of decoherence resulting from the projection…

Quantum Physics · Physics 2009-11-10 Roland Omnes

We propose a solid-state experiment to study the process of continuous quantum measurement of a qubit state. The experiment would verify that an individual qubit stays coherent during the process of measurement (in contrast to the gradual…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Alexander N. Korotkov

The operational meaning of coherence measure lies at very heart of the coherence theory. In this paper, we provide an operational interpretation for geometric coherence, by proving that the geometric coherence of a quantum state is equal to…

Quantum Physics · Physics 2018-09-26 Chunhe Xiong , Junde Wu

The standard generic quantum computer model is studied analytically and numerically and the border for emergence of quantum chaos, induced by imperfections and residual inter-qubit couplings, is determined. This phenomenon appears in an…

Quantum Physics · Physics 2009-11-06 D. L. Shepelyansky

It is shown that coherence resonance, a phenomenon in which regularity of noise-induced oscillations in nonlinear excitable systems is maximized at a certain optimal noise intensity, can be observed in quantum dissipative systems. We…

Adaptation and Self-Organizing Systems · Physics 2021-04-12 Yuzuru Kato , Hiroya Nakao

We exhibit three inequalities involving quantum measurement, all of which are sharp and state independent. The first inequality bounds the performance of joint measurement. The second quantifies the trade-off between the measurement quality…

Quantum Physics · Physics 2021-08-18 Bas Janssens

In quantum metrology and quantum simulation, a coherent non-classical state must be manipulated before unwanted interactions with the environment lead to decoherence. In atom interferometry, the non-classical state is a spatial…

Atomic Physics · Physics 2024-08-19 Cristian D. Panda , Matthew Tao , James Egelhoff , Miguel Ceja , Victoria Xu , Holger Müller

The common use in literature of orthogonal measurements in obtaining quantum discord for two-qubit states is discussed and compared with more general measurements. We prove the optimality of orthogonal measurements for rank 2 states. While…

Quantum Physics · Physics 2012-02-01 Fernando Galve , Gianluca Giorgi , Roberta Zambrini

Measurement outcomes of a quantum state can be genuinely random (unpredictable) according to the basic laws of quantum mechanics. The Heisenberg-Robertson uncertainty relation puts constrains on the accuracy of two noncommuting observables.…

Quantum Physics · Physics 2017-09-13 Xiao Yuan , Ge Bai , Tianyi Peng , Xiongfeng Ma

Quantum-enhanced measurements use highly non-classical quantum states in order to enhance the precision of the measurement of classical quantities, like the length of an optical cavity. The major goal is to beat the standard quantum limit…

Quantum Physics · Physics 2009-05-29 Daniel Braun , John Martin

Unspeakable coherence is a key feature separating quantum and classical physics. Modelled as asymmetry with respect to a continuous transformation generated by a physically relevant observable, such as the Hamiltonian or angular moment,…

Quantum Physics · Physics 2025-12-05 Benjamin Stratton , Chung-Yun Hsieh , Paul Skrzypczyk

We study quantum tomography based on a stochastic continuous-time measurement record obtained from a probe field collectively interacting with an ensemble of identically prepared systems. In comparison to previous studies, we consider here…

Quantum Physics · Physics 2014-10-01 Robert L. Cook , Carlos A. Riofrío , Ivan H. Deutsch

The quantum coherence of a multipartite system is investigated when some of the parties are moving with uniform acceleration and the analysis is carried out using the single mode approximation. Due to acceleration the quantum coherence is…

We investigate the $l_{1}$ norm of coherence of quantum states in mutually unbiased bases. We find that the sum of squared $l_{1}$ norm of coherence of the mixed state single qubit is less than two. We derive the $l_{1}$ norm of coherence…

Quantum Physics · Physics 2019-04-24 Yao-Kun Wang , Li-Zhu Ge , Yuan-Hong Tao