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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

Non-statistical weak measurements yield weak values that are outside the range of eigenvalues and are not rare, suggesting that weak values are a property of every pre-and-post-selected ensemble. They also extend the applicability and valid…

Quantum Physics · Physics 2009-11-13 Jeff Tollaksen , Yakir Aharonov

The AAV effect is the well-known phenomenon where a weak measurement followed by post-selection leads to a pointer shift proportional to the weak value of the measured observable. The effect is usually derived by considering a perturbative…

Quantum Physics · Physics 2014-06-04 Jeff Z. Salvail

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

The indeterminism of quantum mechanics generally permits the independent specification of both an initial and a final condition on the state. Quantum pre-and-post-selection of states opens up a new, experimentally testable, sector of…

Quantum Physics · Physics 2015-06-17 Paul Davies

A model is proposed for the statistical analysis of arbitrary-strength quantum measurements, based on a picture of "sampling weak values" from different configurations of the system. The model is comprised of two elements: a "local weak…

Quantum Physics · Physics 2007-05-23 Alonso Botero

Weak values arise in quantum theory when the result of a weak measurement is conditioned on a subsequent strong measurement. The majority of the trials are discarded, leaving only very few successful events. Intriguingly those can display a…

Quantum Physics · Physics 2016-05-19 George C. Knee , Joshua Combes , Christopher Ferrie , Erik M. Gauger

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

Weak values are the fundamental values for observables in a pre- and post-selected system. Weak values are typically measured by weak measurement, in which weak values appear in the change of not the pre- and post-selected system but the…

Quantum Physics · Physics 2020-04-21 Kazuhisa Ogawa , Hirokazu Kobayashi , Akihisa Tomita

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

A large literature has grown up around the proposed use of 'weak measurements' (i.e., unsharp measurements followed by post-selection) to allegedly provide information about hidden ontological features of quantum systems. This paper…

Quantum Physics · Physics 2017-05-16 R. E. Kastner

A quantum transition can be seen as a result of interference between various pathways(e.g. Feynman paths) which can be labelled by a variable $f$. An attempt to determine the value of f without destroying the coherence between the pathways…

Quantum Physics · Physics 2009-05-26 D. Sokolovski

Postselection following weak measurements has long been investigated for its peculiar manifestation of quantum signatures. In particular, the postselected events can give rise to anomalous values lying outside the spectrum of the measured…

Quantum Physics · Physics 2019-09-04 Valeria Cimini , Ilaria Gianani , Fabrizio Piacentini , Ivo P. Degiovanni , Marco Barbieri

In the weak measurement formalism of Y. Aharonov et al. the so-called weak value A_w of any observable A is generally a complex number. We derive a physical interpretation of its value in terms of the shift in the measurement pointer's mean…

Quantum Physics · Physics 2009-11-13 Richard Jozsa

Weak measurement of a quantum system followed by postselection based on a subsequent strong measurement gives rise to a quantity called the weak value: a complex number for which the interpretation has long been debated. We analyse the…

Quantum Physics · Physics 2015-07-16 Angela Karanjai , Eric G. Cavalcanti , Stephen D. Bartlett , Terry Rudolph

The exact conditions on valid pointer states for weak measurements are derived. It is demonstrated that weak measurements can be performed with any pointer state with vanishing probability current density. This condition is found both for…

Quantum Physics · Physics 2009-11-10 Lars M. Johansen

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

The products of weak values of quantum observables are shown to be of value in deriving quantum uncertainty and complementarity relations, for both weak and strong measurement statistics. First, a 'product representation formula' allows the…

Quantum Physics · Physics 2016-06-08 Michael J. W. Hall , Arun Kumar Pati , Junde Wu

We introduce contextual values as a generalization of the eigenvalues of an observable that takes into account both the system observable and a general measurement procedure. This technique leads to a natural definition of a general…

Quantum Physics · Physics 2010-06-16 J. Dressel , S. Agarwal , A. N. Jordan

The variance of an arbitrary pointer observable is considered for the general case that a complex weak value is measured using a complex valued pointer state. For the typical cases where the pointer observable is either its position or…

Quantum Physics · Physics 2015-05-27 A. D. Parks , J. E. Gray