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Aharonov's weak value amplification realized via weak measurement provides a versatile means to measure physical parameters with high accuracy, similar to quantum resonance epitomized by the Rabi and Ramsey resonances. The similarity…

Quantum Physics · Physics 2025-09-30 Daiki Ueda , Izumi Tsutsui

Weak values are quantities accessed through quantum experiments involving weak measurements and post-selection. It has been shown that 'anomalous' weak values (those lying beyond the eigenvalue range of the corresponding operator) defy…

Quantum Physics · Physics 2019-10-23 Ravi Kunjwal , Matteo Lostaglio , Matthew F. Pusey

We analyze the average of weak values over statistical ensembles of pre- and post-selected states. The protocol of weak values, proposed by Aharonov et al., is the result of a weak measurement conditional on the outcome of a subsequent…

Mesoscale and Nanoscale Physics · Physics 2010-01-18 Alessandro Romito , Yuval Gefen

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

We study the weak values of a quantum observable from the point of view of the Wigner formalism. The main actor is here the cross-Wigner transform of two functions, which is in disguise the cross-ambiguity function familiar from radar…

Quantum Physics · Physics 2015-05-30 Maurice A. de Gosson , Serge M. de Gosson

Quantum metrology is being gradually studied for weak measurement systems. For weak measurement systems with thermal state pointer, we find that in the displacement space corresponding to imaginary weak values, the maximal QFI after…

Quantum Physics · Physics 2018-11-13 Gang Li , Li-Bo Chen , Tao Wang , Zhi-Hui He , He-Shan Song

The weak value approximation has been in use for thirty-five years, but it has not as of yet received a truly complete derivation, leaving its mathematical validity in a state of limbo. Herein, I fill this gap, deriving the weak value…

Quantum Physics · Physics 2026-01-12 Benjamin Noë Bauml

Classical-realistic analysis of entangled systems have lead to retrodiction paradoxes, which ordinarily have been dismissed on the grounds of counter-factuality. Instead, we claim that such paradoxes point to a deeper logical structure…

Quantum Physics · Physics 2015-06-26 Yakir Aharonov , Alonso Botero , Sandu Popescu , Benni Reznik , Jeff Tollaksen

We propose an experimental setup for the implementation of weak measurements in the context of the gedankenexperiment known as Hardy's Paradox. As Aharonov et al. showed, these weak values form a language with which the paradox can be…

Quantum Physics · Physics 2009-11-10 S. E. Ahnert , M. C. Payne

Weak values are traditionally obtained using a weak interaction between the measured system and a pointer state. It has, however, been pointed out that weak coupling can be replaced by a carefully tailored strong interaction. This paper…

Quantum Physics · Physics 2020-06-24 Jan Roik , Karel Lemr , Antonín Černoch , Karol Bartkiewicz

A so called 'weak value' of an observable in quantum mechanics (QM) may be obtained in a weak measurement + post-selection procedure on the QM system under study. Applied to number operators, it has been invoked in revisiting some QM…

Quantum Physics · Physics 2015-06-12 Bengt E Y Svensson

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

While there is a rigorously proven relationship about uncertainties intrinsic to any quantum system, often referred to as "Heisenberg's Uncertainty Principle," Heisenberg originally formulated his ideas in terms of a relationship between…

While quantum reality can be probed through measurements, the Two-State-Vector formalism (TSVF) reveals a subtler reality prevailing between measurements. Under special pre- and post-selections, odd physical values emerge. This unusual…

Quantum Physics · Physics 2018-11-13 Yakir Aharonov , Eliahu Cohen , Mordecai Waegell , Avshalom C. Elitzur

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

The physical meaning of weak values and measurements can be completely understood with Born rule and the general probability theory. It is known that the weak value of an observable $\hat A$ with post-selection $\langle F|$ may be out of…

Quantum Physics · Physics 2018-07-02 Riuji Mochizuki

The application of postselection to a weak quantum measurement leads to the phenomenon of weak values. Expressed in units of the measurement strength, the displacement of a quantum coherent measuring device is ordinarily bounded by the…

Quantum Physics · Physics 2014-03-10 George C. Knee , Erik M. Gauger

The outcomes of a series of measurements, made on a quantum system, form a sequence of random events which occur in a particular order. The system, together with a meter or meters, can be seen as following the paths of a stochastic network…

Quantum Physics · Physics 2016-08-01 D. Sokolovski

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 2011-12-26 Jeff S. Lundeen , Charles Bamber

We examine weak measurements of arbitrary observables where the object is prepared in a mixed state and on which measurements with imperfect detectors are made. The weak value of an observable can be expressed as a conditional expectation…

Quantum Physics · Physics 2009-11-10 Lars M. Johansen , Alfredo Luis