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We contrast two sets of conditions that govern the transition in which classical dynamics emerges from the evolution of a quantum system. The first was derived by considering the trajectories seen by an observer (dubbed the ``strong''…

Quantum Physics · Physics 2009-11-13 Benjamin D. Greenbaum , Kurt Jacobs , Bala Sundaram

Closed expressions are derived for the quantum measurement statistics of pre-and postselected gaussian particle beams. The weakness of the pre-selection step is shown to compete with the non-orthogonality of post-selection in a transparent…

Quantum Physics · Physics 2010-04-14 Tamas Geszti

Postselection is an operation that allows the selection of specific measurement outcomes. It serves as a powerful theoretical tool for enhancing the performance of existing quantum algorithms. Despite recent developments such as time…

General Physics · Physics 2024-09-09 Alex Linden , Betül Gül

We aim to address the following question: if we start with a quantum state with a spontaneously broken higher-form symmetry, what is the fate of the system under weak local quantum measurements? We demonstrate that under certain conditions,…

Strongly Correlated Electrons · Physics 2024-05-21 Kaixiang Su , Nayan Myerson-Jain , Chong Wang , Chao-Ming Jian , Cenke Xu

Quantum mechanical weak values of projection operators have been used to answer which-way questions, e.g. to trace which arms in a multiple Mach-Zehnder setup a particle may have traversed from a given initial to a prescribed final state. I…

Quantum Physics · Physics 2017-03-08 B. E. Y. Svensson

The equation of motion for a time-independent weak value of a quantum mechanical observable contains a complex valued energy factor - the weak energy of evolution. This quantity is defined by the dynamics of the pre-selected and…

Quantum Physics · Physics 2015-06-15 Allen D. Parks

A program was recently initiated to bridge the gap between the Planck scale physics described by loop quantum gravity and the familiar low energy world. We illustrate the conceptual problems and their solutions through a toy model: quantum…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Abhay Ashtekar , Stephen Fairhurst , Joshua L. Willis

The concept of a modular value of an observable of a pre- and post-selected quantum system is introduced. It is similar in form and in some cases has a close connection to the weak value of an observable, but instead of describing an…

Quantum Physics · Physics 2011-05-17 Yaron Kedem , Lev Vaidman

The transport of ultra-cold atoms in magneto-optical potentials provides a clean setting in which to investigate the distinct predictions of classical versus quantum dynamics for a system with coupled degrees of freedom. In this system,…

The problem of feedback control of quantum systems by means of weak measurements is investigated in detail. When weak measurements are made on a set of identical quantum systems, the single-system density matrix can be determined to a high…

Quantum Physics · Physics 2009-10-31 Seth Lloyd , Jean-Jacques E. Slotine

Nascent quantum computers motivate the exploration of quantum many-body systems in nontraditional scenarios. For example, it has become natural to explore the dynamics of systems evolving under both unitary evolution and measurement. Such…

Statistical Mechanics · Physics 2024-03-15 Nicholas O'Dea , Alan Morningstar , Sarang Gopalakrishnan , Vedika Khemani

Using the quantum transition path time probability distribution we show that time averaging of weak values leads to unexpected results. We prove a weak value time energy uncertainty principle and time energy commutation relation. We also…

Quantum Physics · Physics 2018-09-05 Eli Pollak , S. Miret-Artés

We consider a physical system in which the description of states and measurements follow the usual quantum mechanical rules. We also assume that the dynamics is linear, but may not be fully quantum (i.e unitary). We show that in such a…

Quantum Physics · Physics 2009-10-31 Aditi Sen De , Ujjwal Sen

Tunnel amplitudes of molecular configurations (like neuronal channel pores) may be very sensitive to thermal vibrations of the barrier width (vibration-assisted tunneling) resulting in pseudo-random spikes of widely varying sizes. An…

Quantum Physics · Physics 2007-05-23 L. Polley

Weak measurements offer the possibility of tuning the information acquired on a system, hence the imposed disturbance. This suggests that it could be a useful tool for multi-parameter estimation, when two parameters can not be measured…

Quantum Physics · Physics 2015-10-05 Matteo Altorio , Marco G. Genoni , Mihai D. Vidrighin , Fabrizia Somma , Marco Barbieri

We investigate in this work the meaning of weak values through the prism of property ascription in quantum systems. Indeed, the weak measurements framework contains only ingredients of the standard quantum formalism, and as such weak…

Quantum Physics · Physics 2019-03-25 A. Matzkin

Pushing forward the understanding of general non-unitary dynamics in controlled quantum platforms has been fueled by the recent discovery of measurement-induced phases and phase transitions. So far, these transitions remained largely…

Disordered Systems and Neural Networks · Physics 2022-08-24 M. Buchhold , T. Müller , S. Diehl

We prove uncertainty relations that quantitatively express the impossibility of jointly sharp preparation of pre- and post-selected quantum states for measuring incompatible observables during the weak measurement. By defining a suitable…

Quantum Physics · Physics 2014-11-27 Arun Kumar Pati , Junde Wu

We present a Bohmian description of a decaying quantum system. A particle is initially confined in a region around the origin which is surrounded by a repulsive potential barrier. The particle leaks out in time tunneling through the…

Quantum Physics · Physics 2014-12-05 Y. Nogami , F. M. Toyama , W. van Dijk

Quantum measurement is a process that involves the interaction between a quantum system and a macroscopic measurement apparatus containing many degrees of freedom. The photodetector is such an apparatus with many electrons interacting with…

Quantum Physics · Physics 2022-08-31 Yubao Liu , Haixing Miao , Yanbei Chen , Yiqiu Ma