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Weak measurement is a novel quantum measurement scheme, which is usually characterized by the weak value formalism. To guarantee the validity of the weak value formalism, the fidelity between the pre-selection and the post-selection should…

Quantum Physics · Physics 2015-06-05 Shengshi Pang , Shengjun Wu , Zeng-Bing Chen

Weak values are usually associated with weak measurements of an observable on a pre- and post-selected ensemble. We show that more generally, weak values are proportional to the correlation between two pointers in a successive measurement.…

Quantum Physics · Physics 2009-08-03 Lars M. Johansen , Pier A. Mello

We derive schemes to measure the so-called weak values of quantum system observables by coupling of the system to a qubit meter system. We highlight, in particular, the meaning of the imaginary part of the weak values, and show how it can…

Quantum Physics · Physics 2015-05-14 Shengjun Wu , Klaus Mølmer

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

Weak amplification is a signal enhancement technique which is used to measure tiny changes that otherwise cannot be determined because of technical limitations. It is based on the existence of a special type of interaction which couples a…

Quantum Physics · Physics 2015-06-04 Juan P. Torres , Graciana Puentes , Nathaniel Hermosa , Luis Jose Salazar-Serrano

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

It is argued that a weak value of an observable is a robust property of a single pre- and post-selected quantum system rather than a statistical property. During an infinitesimal time a system with a given weak value affects other systems…

A general approach to the measurement of an observable with pre- and post-selection is presented. The limit of weak measurement is studied in detail, and it is shown that the phase of the probe, including a Hamiltonian contribution to it,…

Quantum Physics · Physics 2008-04-19 Antonio Di Lorenzo , J. Carlos Egues

It was recently pointed out (and demonstrated experimentally) by Lundeen et al. that the wave function of a particle (more precisely, the wave function possessed by each member of an ensemble of identically-prepared particles) can be…

Quantum Physics · Physics 2014-10-30 Travis Norsen , Ward Struyve

A precise definition of "weak [quantum] measurements" and "weak value" (of a quantum observable) is offered, and simple finite dimensional examples are given showing that weak values are not unique and therefore probably do not correspond…

Quantum Physics · Physics 2009-10-01 Stephen Parrott

A simple formula to read out the weak value from the wave function of the measuring device after the postselection with the initial Gaussian profile is proposed. We apply this formula for the weak value to the classical experiment of the…

Quantum Physics · Physics 2016-11-25 Kouji Nakamura

Weak measurements are a unique tool for accessing information about weakly interacting quantum systems with minimal back action. Joint weak measurements of single-particle operators with pointer states characterized by a two-dimensional…

Quantum Physics · Physics 2012-11-13 G. Puentes , N. Hermosa , J. P. Torres

Conventional quantum mechanics describes a pre- and post-selected system in terms of virtual (Feynman) paths via which the final state can be reached. In the absence of probabilities, a weak measurement (WM) determines the probability…

Quantum Physics · Physics 2016-04-20 D. Sokolovski

Precise definitions of "weak [quantum] measurements" and "weak value" [of a quantum observable] are offered, which seem to capture the meaning of the often vague ways that these terms are used in the literature. Simple finite dimensional…

Quantum Physics · Physics 2010-01-11 Stephen Parrott

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

Weak values are typically obtained experimentally by performing weak measurements, which involve weak interactions between the measured system and a probe. However, the determination of weak values does not necessarily require weak…

Recent work [J.S. Lundeen et al. Nature, 474, 188 (2011)] directly measured the wavefunction by weakly measuring a variable followed by a normal (i.e. `strong') measurement of the complementary variable. We generalize this method to mixed…

Quantum Physics · Physics 2012-03-14 Jeff S. Lundeen , Charles Bamber

Weak measurement with a coherent state pointer and in combination with an orthogonal postselection can lead to a surprising amplification effect, and we give a fire-new physical mechanism about the weak measurement in order to understand…

Quantum Physics · Physics 2015-09-03 Gang Li , Ming-Yong Ye , Xiu-Min Lin , He-Shan Song

In the weak measurement (WM) scenario involving weak interaction and postselection by projective measurement, the empirical significance of weak values is manifested in terms of shifts in the measurement pointer's mean position and mean…

Quantum Physics · Physics 2016-11-18 Som Kanjilal , Girish Muralidhara , Dipankar Home

In contrast to a projective quantum measurement in which the system is projected onto an eigenstate of the measured operator, in a weak measurement the system is only weakly perturbed while only partial information on the measured…

Quantum Physics · Physics 2018-10-26 Maicol A. Ochoa , Wolfgang Belzig , Abraham Nitzan