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IIt is shown that a weak measurement of a quantum system produces a new state of the quantum system which depends on the prior state, as well as the (uncontrollable) measured position of the pointer variable of the weak measurement…

Quantum Physics · Physics 2013-05-29 D. J. Miller

Constructing an ontology for quantum theory is challenging, in part due to unavoidable measurement back-action. The Aharonov-Albert-Vaidman weak measurement formalism provides a method to predict measurement results (weak values) in a…

Quantum Physics · Physics 2019-09-04 Josiah Sinclair , David Spierings , Aharon Brodutch , Aephraim M. Steinberg

I show that the application of the quantum-mechanical (QM) which-way weak measurement scheme of Vaidman may lead to logical inconsistencies. To this end, I study weak values of projection operators. Weak values are (normalized) amplitudes,…

Quantum Physics · Physics 2018-04-16 B. E. Y. Svensson

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 propose an interferometric measurement of weak forces using a single ion subjected to designed time-dependent spin-dependent forces. Explicit expressions of the relation between the unknown force and the final populations are found…

Quantum Physics · Physics 2018-10-24 S. Martínez-Garaot , A. Rodriguez-Prieto , J. G. Muga

The standard approach to quantum measurements is to assume that they lead to effectively instantaneous collapse of the quantum state. However, if we assume that we are unable to enforce at what exact moment of time the measurement occurs…

Quantum Physics · Physics 2026-03-20 Igor Prlina , Milutin Živković

Weak measurements performed between quantum state preparation and post-selection result in complex values for self-adjoint operators, corresponding to complex conditional probabilities for the projections on specific eigenstates. In this…

Quantum Physics · Physics 2011-10-14 Holger F. Hofmann

Weak measurements may result in extra quantity of quantumness of correlations compared with standard projective measurement on a bipartite quantum state. We show that the quantumness of correlations by weak measurements can be consumed for…

Quantum Physics · Physics 2014-03-18 Lin-Ping Huai , Bo Li , Shi-Xian Qu , Heng Fan

Unitary evolution and projective measurement are fundamental axioms of quantum mechanics. Even though projective measurement yields one of the eigenstates of the measured operator as the outcome, there is no theory that predicts which…

Quantum Physics · Physics 2015-06-24 Apoorva Patel , Parveen Kumar

"Weak measurements" -- involving a weak unitary interaction between a quantum system and a meter followed by a projective measurement -- are investigated when the system has a non-Hermitian Hamiltonian. We show in particular how the…

Quantum Physics · Physics 2012-12-21 A. Matzkin

Quantum mechanics does not permit joint measurements of non-commuting observables. However, it is possible to measure the weak value of a projection operator, followed by the precise measurement of a different property. The results can be…

Quantum Physics · Physics 2015-02-25 Holger F. Hofmann

The usual conjectures of quantum measurements approaches, inspired from the traditional interpretation of Heisenberg's ("uncertainty") relations, are proved as being incorrect. A group of reconsidered conjectures and a corresponding new…

Quantum Physics · Physics 2007-05-23 Spiridon Dumitru

Negative probability values have been widely employed as an indicator of the nonclassicality of quantum systems. Known as a quasiprobability distribution, they are regarded as a useful tool that provides significant insight into the…

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

We extend the idea of weak measurements to the general case, provide a complete treatment and obtain results for both the regime when the pre-selected and post-selected states (PPS) are almost orthogonal and the regime when they are exactly…

Quantum Physics · Physics 2015-03-17 Shengjun Wu , Yang Li

Recently, weak measurements were used to measure small effects that are transverse to the propagation direction of a light beam. Here we address the question whether weak measurements are also useful for measuring small longitudinal phase…

Quantum Physics · Physics 2010-07-12 Nicolas Brunner , Christoph Simon

We develop a formal theory of the weak values with emphasis on the consistency conditions and a probabilistic interpretation in the counter-factual processes. We present the condition for the choice of the post-selected state to give a…

Quantum Physics · Physics 2010-08-19 Akio Hosoya , Yutaka Shikano

Quantum weak measurement has attracted much interest recently [J. Dressel et al., Rev. Mod. Phys. 86, 307 (2014)] because it could amplify some weak signals and provide a technique to observe nonclassical phenomena. Here, we apply this…

Quantum Physics · Physics 2015-11-04 M. Zhang , S. Y. Zhu

The weak values and weak measurement formalism were initially limited to pure states, which were later extended to mixed states, leading to intriguing applications in quantum information processing tasks. Weak values are considered to be…

Quantum Physics · Physics 2025-11-04 Rajendra Singh Bhati

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