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The physical interpretation of weak measurements has been the subject of much debate. It is known that anomalous phenomena and results that appear in weak measurements are essentially related to the phase of the quantum system being…

Quantum Physics · Physics 2024-10-29 Nobuharu Nakajima

This work will incorporate a few related tools for addressing the conceptual difficulties arising from sewing together classical and quantum mechanics: deterministic operators, weak measurements and post-selection. Weak Measurement, based…

Quantum Physics · Physics 2016-12-21 Eliahu Cohen , Yakir Aharonov

Weak values of quantum observables are a powerful tool for investigating quantum phenomena. Some methods for measuring weak values in the laboratory require weak interactions and postselection, while others are deterministic, but require…

Quantum Physics · Physics 2024-10-18 Giulio Chiribella , Kyrylo Simonov , Xuanqiang Zhao

We consider highly inaccurate measurements made on classical stochastic and quantum systems. In the quantum case such a \e{weak} measurement preserves coherence between the system's alternatives. We demonstrate that in both cases the…

Quantum Physics · Physics 2026-03-16 D. Sokolovski , D. Alonso , S. Brouard

Encoding the imaginary part of a weak value onto an initially entangled probe can modify its entanglement content - provided the probe observable can distinguish between states of different entropies. Apart from fundamental interest, this…

Quantum Physics · Physics 2009-11-13 David Menzies , Natalia Korolkova

For continuous weak measurement of qubits, we obtain exact expressions for weak values (WVs) from the post-selection restricted average of measurement outputs, by using both the quantumtrajectory- equation (QTE) and quantum Bayesian…

Quantum Physics · Physics 2016-02-29 Lupei Qin , Pengfei Liang , Xin-Qi Li

In this article, we study quantum coherence of bipartite state from the perspective of weak measurement, which generalizes the notion of coherence relative to measurement. The is being illustrated by computing coherence for the well-known…

Quantum Physics · Physics 2023-04-06 Indrajith V. S , R. Muthuganesan , R. Sankaranarayanan

The quantum mechanical weak value $A_w=\left\langle \phi|A|\psi \right \rangle / \left\langle \phi | \psi \right\rangle$ of an observable $A$ is a measurable quantity associated with an observable $A$ and pre- and post-selected states…

Quantum Physics · Physics 2023-10-27 Rafael Wagner , Ernesto F. Galvão

The impossibility of measuring noncommuting quantum mechanical observables is one of the most fascinating consequences of the quantum mechanical postulates. Hence, to date the investigation of quantum measurement and projection is a…

Mesoscale and Nanoscale Physics · Physics 2010-09-06 Adam Bednorz , Wolfgang Belzig

The weak energy condition is known to fail in general when applied to expectation values of the the energy momentum tensor in flat space quantum field theory. It is shown how the usual counter arguments against its validity are no longer…

High Energy Physics - Theory · Physics 2009-10-30 J. I. Latorre , H. Osborn

Time averaging of weak values using the quantum transition path time probability distribution enables us to establish a general uncertainty principle for the weak values of two not necessarily Hermitian operators. This new principle is a…

Quantum Physics · Physics 2019-01-16 Eli Pollak , Salvador Miret-Artés

We study a phenomenon occuring in various areas of quantum physics, in which an observable density (such as an energy density) which is classically pointwise nonnegative may assume arbitrarily negative expectation values after quantisation,…

Mathematical Physics · Physics 2007-05-23 Simon P. Eveson , Christopher J. Fewster , Rainer Verch

The time-symmetric formalism endows the weak measurement and its outcome, the weak value,many unique features. In particular, it allows a direct tomography of quantum states without resort to complicated reconstruction algorithms and…

Quantum Physics · Physics 2021-11-01 Liang Xu , Huichao Xu , Tao Jiang , Feixiang Xu , Kaimin Zheng , Ben Wang , Aonan Zhang , Lijian Zhang

To describe the pre- and post-selected quantum ensembles, a complex quantity called the weak value of an operator is used. The weak value is highly controversial due to the fact that it is not bounded by the possible eigenvalues of the…

Quantum Physics · Physics 2023-03-20 Aiham M. Rostom

The quantum kinetic equation used in the study of weak turbulence is reconsidered in the context of a theory with a generic quartic interaction. The expectation value of the time derivative of the mode number operators is computed in a…

Condensed Matter · Physics 2009-10-28 Mark Rakowski , Siddhartha Sen

We investigate the power of weak measurements in the framework of quantum state discrimination. First, we define and analyze the notion of weak consecutive measurements. Our main result is a convergence theorem whereby we demonstrate when…

Quantum Physics · Physics 2015-06-23 Boaz Tamir , Eliahu Cohen , Avner Priel

Hardy's paradox is analysed within Feynman's formulation of quantum mechanics. A transition amplitude is represented as a sum over virtual paths which different intermediate measurements convert into different sets of real pathways.…

Quantum Physics · Physics 2009-11-13 D. Sokolovski , I. Puerto Gimenez , R. Sala Mayato

An analysis of errors in measurement yields new insight into classically forbidden quantum processes. In addition to "physical" values, a realistic measurement can yield "unphysical" values; we show that in {\it sequences} of measurements,…

Condensed Matter · Physics 2009-10-22 Daniel Rohrlich , Yakir Aharonov , Sandu Popescu , Lev Vaidman

In the Aharonov-Albert-Vaidman (AAV) weak measurement, it is assumed that the measuring device or the pointer is in a quantum mechanical pure state. In reality, however, it is often not the case. In this paper, we generalize the AAV weak…

Quantum Physics · Physics 2010-02-25 Young-Wook Cho , Hyang-Tag Lim , Young-Sik Ra , Yoon-Ho Kim

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
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