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We consider using Hamiltonian feedback control to increase the speed at which a continuous measurement purifies (reduces) the state of a quantum system, and thus to increase the speed of the preparation of pure states. For a measurement of…

Quantum Physics · Physics 2009-08-15 Joshua Combes , Kurt Jacobs

Simulating the dynamics of complex quantum systems is a central application of quantum devices. Here, we propose leveraging the power of measurements to simulate short-time quantum dynamics of physically prepared quantum states in classical…

Quantum Physics · Physics 2025-07-02 Paul K. Faehrmann , Jens Eisert , Maria Kieferova , Richard Kueng

We study a motion of quantum particles, whose properties depend on one coordinate so that they can move freely in the perpendicular direction. A rotationally-symmetric Hamiltonian is derived and applied to study a general interface formed…

Condensed Matter · Physics 2009-10-31 A. V. Kolesnikov , A. P. Silin

The Projection Postulate from Standard Quantum Mechanics relies fundamentally on measurements. But measurements implicitly suggest the existence of anthropocentric notions like measuring devices, which should rather emerge from the theory.…

Quantum Physics · Physics 2021-03-26 Ovidiu Cristinel Stoica

In this report, we study the reduced conditional dynamics of a quantum system in the case of indirect quantum measurement. The detectors microscopic part (pointer) interacts with the measured system (target) and the environment, which…

Quantum Physics · Physics 2013-11-06 George Miroshnichenko , Alexander Trifanov

Studies of muonic hydrogen atoms and molecules have been performed traditionally in bulk targets of gas, liquid or solid. At TRIUMF, Canada's meson facility, we have developed a new type of target system using multilayer thin films of solid…

We prove that the Hilbert space description of all joint von Neumann measurements on a quantum state can be reproduced in terms of a single measure space ({\Omega}, F, {\mu}) with a normalized real-valued measure {\mu}, that is, in terms of…

Quantum Physics · Physics 2012-10-12 Elena R. Loubenets

Explaining the emergence of classical properties of a quantum system through its interaction with the environment has been one of the promising ideas on how to understand the notorious quantum-to-classical transition. A pivotal role in this…

Quantum Physics · Physics 2024-01-24 Uttam Singh , Adam Sawicki , Jarosław K. Korbicz

In this paper, we discuss that an observable-based single-system Copenhagen and entanglement-based two-system von Neumann measurement protocols in quantum theory can be made equivalent by considering the second part of the two-system scheme…

General Physics · Physics 2015-08-17 Daegene Song

In this paper we investigate the Quantum Brownian motion of a point particle induced by quantum vacuum fluctuations of a massless scalar field in (3 + 1)-dimensional Minkowski spacetime with distinct conditions (Dirichlet, Neumann, mixed…

High Energy Physics - Theory · Physics 2023-05-10 Éwerton J. B. Ferreira , Eliza M. B. Guedes , Herondy F. Santana Mota

Experimentally observed violations of Bell inequalities rule out local realistic theories. Consequently, the quantum state vector becomes a strong candidate for providing an objective picture of reality. However, such an ontological view of…

Quantum Physics · Physics 2007-05-23 Bernd A. Berg

Two measurable characteristics of microwave one-mode photon states are discussed: a rotated quadrature distribution (tomogram) and normally/antinormally ordered moments of photon creation and annihilation operators. Extraction of these…

Quantum Physics · Physics 2011-09-16 Sergey N. Filippov , Vladimir I. Man'ko

Von Neumann projections are the main operations by which information can be extracted from the quantum to the classical realm. They are however static processes that do not adapt to the states they measure. Advances in the field of adaptive…

Quantum Physics · Physics 2015-10-28 Amine Laghaout , Ulrik L. Andersen

Weak measurements in combination with post-selection can give rise to a striking amplification effect (related to a large "weak value"). We show that this effect can be understood by viewing the initial state of the pointer as the ground…

Quantum Physics · Physics 2015-05-20 Christoph Simon , Eugene S. Polzik

We propose a scheme to experimentally observe matter-wave interference in the time domain, specifically in the arrival-time or the time-of-flight (TOF) distribution for atomic BEC Schrodinger-cat state represented by superposition of…

Quantum Physics · Physics 2015-05-13 Md. Manirul Ali , Hsi-Sheng Goan

Measurements take a singular role in quantum theory. While they are often idealized as an instantaneous process, this is in conflict with all other physical processes in nature. In this Letter, we adopt a standpoint where the interaction…

Quantum Physics · Physics 2023-11-15 Nathan Shettell , Federico Centrone , Luis Pedro García-Pintos

We calculate the quantum Fisher information for a generic many-body fermionic system in a pure state depending on a parameter. We discuss the situations where the parameter is imprinted in the basis states, in the state coefficients, or…

Quantum Physics · Physics 2023-03-21 Olivier Giraud , Mark-Oliver Goerbig , Daniel Braun

What can we learn about quantum gravity from a simple toy model, without actually quantizing it? The toy model consists of a finite number of point particles, coupled to three dimensional Einstein gravity. It has finitely many physical…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Hans-Juergen Matschull

Quantum physics was invented to account for two fundamental features of measurement results -- their discreetness and randomness. Emblematic of these features is Bohr's idea of quantum jumps between two discrete energy levels of an atom.…

An operational time of arrival is introduced using a realistic position and momentum measurement scheme. The phase space measurement involves the dynamics of a quantum particle probed by a measuring device. For such a measurement an…

Quantum Physics · Physics 2009-10-31 Piotr Kochanski , Krzysztof Wodkiewicz