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The influence of repeated projective measurements on the dynamics of the state of a quantum system is studied in dependence of the time lag $\tau$ between successive measurements. In the limit of infinitely many measurements of the…

Quantum Physics · Physics 2012-02-16 Juyeon Yi , Peter Talkner , Gert-Ludwig Ingold

In a continuous measurement scheme a spin-1/2 particle can be measured and simultaneously driven by an external resonant signal. When the driving is weak, it does not prevent the particle wave-function from collapsing and a detector…

Recent development in quantum information sciences and technologies, especially building programmable quantum computers, provide us new opportunities to study fundamental aspects of quantum mechanics. We propose qubit models to emulate the…

Quantum Physics · Physics 2022-06-29 Meng-Jun Hu , Yanbei Chen , Yiqiu Ma , Xiang Li , Yubao Liu , Yong-Sheng Zhang , Haixing Miao

We investigate the role of non-selective measurement on the estimation of system-environment parameters. Projective measurement is the popular method of initial state preparation which always prepares a pure state. However, in various…

Quantum Physics · Physics 2024-09-17 Ali Raza Mirza , Jim Al-Khalili

A foundational result in the theory of quantum computation known as the "principle of safe storage" shows that it is always possible to take a quantum circuit and produce an equivalent circuit that makes all measurements at the end of the…

Computational Complexity · Computer Science 2021-03-05 Bill Fefferman , Zachary Remscrim

Transition amplitudes between instantaneous eigenstates of quantum two-level system are evaluated analytically on the basis of a new parametrization of its evolution operator, which has recently been proposed to construct exact solutions.…

Quantum Physics · Physics 2018-03-28 Takayuki Suzuki , Hiromichi Nakazato , Roberto Grimaudo , Antonino Messina

The protection of quantum states is challenging for non-orthogonal states especially in the presence of noises. The recent research breakthrough shows that this difficulty can be overcome by feedback control with weak measurements. However,…

Quantum Physics · Physics 2015-06-16 Y. Yang , X. Y. Zhang , J. Ma , X. X. Yi

In the scheme of a quantum nondemolition (QND) measurement, an observable is measured without perturbing its evolution. In the context of studies of decoherence in quantum computing, we examine the `open' quantum system of a two-level atom,…

Quantum Physics · Physics 2009-11-13 Subhashish Banerjee , R. Ghosh

This note presents a sufficient condition for partial approximate ensemble controllability of a set of bilinear conservative quantum systems in an infinite dimensional Hilbert space. The proof relies on classical geometric and averaging…

Optimization and Control · Mathematics 2013-03-08 Thomas Chambrion

A numerical method is proposed for simulation of composite open quantum systems. It is based on Lindblad master equations and adiabatic elimination. Each subsystem is assumed to converge exponentially towards a stationary subspace, slightly…

Quantum Physics · Physics 2023-11-10 François-Marie Le Régent , Pierre Rouchon

We experimentally demonstrate a weak measurement and measurement reversal-based scheme to ameliorate the effects of decoherence due to amplitude damping, on an NMR quantum processor. The weak measurement and measurement reversal processes…

Quantum Physics · Physics 2024-09-20 Gayatri Singh , Akshay Gaikwad , Arvind , Kavita Dorai

Ground states of spin lattices can serve as a resource for measurement-based quantum computation. Ideally, the ability to perform quantum gates via measurements on such states would be insensitive to small variations in the Hamiltonian.…

Quantum Physics · Physics 2012-06-20 Dominic V. Else , Ilai Schwarz , Stephen D. Bartlett , Andrew C. Doherty

Measurements can drive quantum many-body systems into nontrivial steady states and induce interesting dynamical phase transitions, rendering measurement-only quantum circuits a useful platform for exploring quantum many-body phases beyond…

Quantum Physics · Physics 2026-05-26 Bihui Zhu

In this study, we investigate quantum nonseparability between an observed system and a measuring apparatus, or multiple measuring apparatuses. We show that the physical meaning of the outcome of the measuring apparatus obtained by weak…

Quantum Physics · Physics 2016-04-11 Riuji Mochizuki

We demonstrate that the task of determining an unknown quantum state can be accomplished efficiently by making a sequential measurement of two observables $\hat{A}$ and $\hat{B}$, provided that the two observables are chosen in such a way…

Quantum Physics · Physics 2013-10-22 Antonio Di Lorenzo

Motivated by the expectation that relativistic symmetries might acquire quantum features in Quantum Gravity, we take the first steps towards a theory of ''Doubly'' Quantum Mechanics, a modification of Quantum Mechanics in which the…

Quantum Physics · Physics 2025-04-30 Vittorio D'Esposito , Giuseppe Fabiano , Domenico Frattulillo , Flavio Mercati

Classically, no transfer occurs between two equally filled reservoirs no matter how one looks at them, but the situation can be different quantum mechanically. This paradoxically surprising phenomenon rests on the distinctive property of…

Quantum Physics · Physics 2015-06-19 Antoine Tilloy , Michel Bauer , Denis Bernard

We introduce a qauantitative measure of spin-charge separation, $\zeta (t)$ which is based on the difference between the fluctuations with respect to background of the spin and charge profiles at any time t and is suitable for studying the…

Strongly Correlated Electrons · Physics 2016-08-16 Amir Youssefi , M. Ansari-Fard , S. A. Jafari

Measurement-induced phase transitions are often studied in random quantum circuits, with local measurements performed with a certain probability. We present here a model where a global measurement is performed with certainty at every…

Quantum Physics · Physics 2026-04-22 Paranjoy Chaki , Protyush Nandi , Ujjwal Sen , Subinay Dasgupta

From the noncommutative nature of quantum mechanics, estimation of canonical observables $\hat{q}$ and $\hat{p}$ is essentially restricted in its performance by the Heisenberg uncertainty relation, $\mean{\Delta \hat{q}^2}\mean{\Delta…

Quantum Physics · Physics 2007-09-24 Naoki Yamamoto , Shinji Hara