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A generic non-integrable (unitary) out-of-equilibrium quantum process, when interrogated across many times, is shown to yield the same statistics as an (non-unitary) equilibrated process. In particular, using the tools of quantum stochastic…

Quantum Physics · Physics 2023-07-18 Neil Dowling , Pedro Figueroa-Romero , Felix A. Pollock , Philipp Strasberg , Kavan Modi

The problem of testing equality of the entire second order structure of two independent functional linear processes is considered. A fully functional $L^2$-type test is developed which evaluates, over all frequencies, the Hilbert-Schmidt…

Methodology · Statistics 2020-04-15 Anne Leucht , Efstathios Paparoditis , Theofanis Sapatinas

The possibility of performing simultaneous measurements in quantum mechanics is investigated in the context of the Curie-Weiss model for a projective measurement. Concretely, we consider a spin-$\frac{1}{2}$ system simultaneously…

Quantum Physics · Physics 2017-06-01 Martí Perarnau-Llobet , Theo M. Nieuwenhuizen

The present paper studies an operator norm that captures the distinguishability of quantum strategies in the same sense that the trace norm captures the distinguishability of quantum states or the diamond norm captures the…

Quantum Physics · Physics 2012-03-16 Gus Gutoski

We propose a time-of-arrival operator in quantum mechanics by conditioning on a quantum clock. This allows us to bypass some of the problems of previous proposals, and to obtain a Hermitian time of arrival operator whose probability…

Quantum Physics · Physics 2020-03-19 Lorenzo Maccone , Krzysztof Sacha

The problem of comparing the entire second order structure of two functional processes is considered and a $L^2$-type statistic for testing equality of the corresponding spectral density operators is investigated. The test statistic…

Statistics Theory · Mathematics 2021-06-29 Anne Leucht , Efstathios Paparoditis , Daniel Rademacher , Theofanis Sapatinas

Two-time expectation values of sequential measurements of dichotomic observables are known to be time symmetric for closed quantum systems. Namely, if a system evolves unitarily between sequential measurements of dichotomic observables…

Quantum Physics · Physics 2024-07-17 Arthur J. Parzygnat , James Fullwood

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

We argue that measurement data in quantum physics can be rigorously interpreted only as a result of a statistical, macroscopic process, taking into account the indistinguishable character of identical particles. Quantum determinism is in…

General Physics · Physics 2025-07-22 Patrick Navez , Henni Ouerdane

It is shown that the full unknown state of a spin-1/2 system, S, which, within Born's statistical interpretation, is meant as the state of an ensamble of identically prepared systems, can be determined with a simultaneous measurement with…

Quantum Physics · Physics 2017-08-23 G. Aquino , B. Mehmani

The quantum properties of quantum measurements are indispensable resources in quantum information processing and have drawn extensive research interest. The conventional approach to reveal the quantum properties relies on the reconstruction…

Quantum Physics · Physics 2021-12-01 Liang Xu , Huichao Xu , Jie Xie , Hui Li , Lin Zhou , Feixiang Xu , Lijian Zhang

Informationally complete measurements allow the estimation of expectation values of any operator on a quantum system, by changing only the data-processing of the measurement outcomes. In particular, an informationally complete measurement…

Quantum Physics · Physics 2007-05-23 G. M. D'Ariano , P. Perinotti , M. F. Sacchi

We describe the conditional and unconditional dynamics of two coupled quantum dots when one dot is subjected to a measurement of its occupation number using a single electron transistor (SET). The measurement is made when the bare tunneling…

Mesoscale and Nanoscale Physics · Physics 2019-08-17 H. M. Wiseman , Dian Wahyu Utami , He Bi Sun , G. J. Milburn , B. E. Kane , A. Dzurak , R. G. Clark

We present a general theory to quantify the uncertainty from imposing structural assumptions on the second-order structure of nonstationary Hilbert space-valued processes, which can be measured via functionals of time-dependent spectral…

Statistics Theory · Mathematics 2023-09-19 Anne van Delft , Holger Dette

This article presents a concrete mathematical framework for the generation of entangled quantum states from classical stochastic processes. We demonstrate that any density operator $\rho_{AB}$ of a composite system can be derived from the…

Quantum Physics · Physics 2026-01-27 Andrei Khrennikov

Space-time is one of the most essential, yet most mysterious concepts in physics. In quantum mechanics it is common to understand time as a marker of instances of evolution and define states around all the space but at one time; while in…

Quantum Physics · Physics 2020-12-01 Tian Zhang , Oscar Dahlsten , Vlatko Vedral

Students in quantum mechanics class are taught that the wave function contains all knowable information about an isolated system. Later in the course, this view seems to be contradicted by the mysterious density matrix, which introduces a…

General Physics · Physics 2021-04-16 Mark G. Kuzyk

This study proposes a time-symmetric framework for quantum measurement that restores microscopic reversibility at the level of the dynamical description while remaining compatible with causality and thermodynamic consistency. Instead of…

Quantum Physics · Physics 2025-12-01 Shin-ichi Inage

A crucial assumption to reduce computational complexity in spatial-temporal data analysis is separability, which factors the covariance structure into a purely spatial and a purely temporal component. In this paper, we develop statistical…

Statistics Theory · Mathematics 2026-03-30 Lujia Bai , Holger Dette , Zihao Yuan

Several stochastic processes with virtual particles in two dimensional space-time are presented whose mean field equations coincide with Schr\"odinger, Dirac, Klein-Gordon and the quantum mechanic equation for a photon. These processes…

Quantum Physics · Physics 2015-11-03 Alberto C. de la Torre