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We refute the widely held belief that the quantum weak value necessarily pertains to weak measurements. To accomplish this, we use the transverse position of a beam as the detector for the conditioned von Neumann measurement of a system…

Quantum Physics · Physics 2013-01-16 J. Dressel , A. N. Jordan

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

In a quantum-noise limited system, weak-value amplification using post-selection normally does not produce more sensitive measurements than standard methods for ideal detectors: the increased weak value is compensated by the reduced power…

Quantum Physics · Physics 2021-06-09 Courtney Krafczyk , Andrew N. Jordan , Michael E. Goggin , Paul G. Kwiat

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 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

Quantum weak measurement, measuring some observable quantities within the selected subensemble of the entire quantum ensemble, can produce many interesting results such as the superluminal phenomena. An outcome of such a measurement is the…

Quantum Physics · Physics 2017-01-24 Miao Zhang

Weak values have been shown to be helpful especially when considering them as the outcomes of weak measurements. In this paper we show that in principle, the real and imaginary parts of the weak value of any operator may be elucidated from…

Quantum Physics · Physics 2018-10-17 Eliahu Cohen , Eli Pollak

The notion of weak measurement provides a formalism for extracting information from a quantum system in the limit of vanishing disturbance to its state. Here we extend this formalism to the measurement of sequences of observables. When…

Quantum Physics · Physics 2009-11-13 Graeme Mitchison , Richard Jozsa , Sandu Popescu

We show that weak measurement can be used to "amplify" optical nonlinearities at the single- photon level, such that the effect of one properly post-selected photon on a classical beam may be as large as that of many un-post-selected…

Quantum Physics · Physics 2015-03-17 Amir Feizpour , Xingxing Xing , Aephraim M. Steinberg

As in modern communication networks, the security of quantum networks will rely on complex cryptographic tasks that are based on a handful of fundamental primitives. Weak coin flipping (WCF) is a significant such primitive which allows two…

Closed expressions are derived for the quantum measurement statistics of pre-and postselected gaussian particle beams. The weakness of the pre-selection step is shown to compete with the non-orthogonality of post-selection in a transparent…

Quantum Physics · Physics 2010-04-14 Tamas Geszti

Recent empirical work in the field of 'weak measurements' has yielded novel ways of more directly accessing and exploring the quantum wavefunction. Measuring either position or momentum for a photon in a 'weak' manner yields a wide range of…

Quantum Physics · Physics 2013-06-17 David R Geelan

In a weak measurement the real and imaginary parts of a weak value participate in the shifts of the complementary variables of a pointer. While the real part represents the value of an observable in the limit of zero measurement strength,…

Quantum Physics · Physics 2019-09-12 Kazuhiro Yokota

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

In this work, we simulate the behavior of photons in a laboratory experiment using a quantum computer and examine how the simulation results compare with the theoretical predictions. The experiment involves both protective and…

Quantum Physics · Physics 2025-08-13 Priyasheel Prasad , Marco Russo , Bartolomeo Montrucchio

A significant obstacle for practical quantum computation is the loss of physical qubits in quantum computers, a decoherence mechanism most notably in optical systems. Here we experimentally demonstrate, both in the quantum circuit model and…

Quantum Physics · Physics 2016-05-16 Chao-Yang Lu , Wei-Bo Gao , Jin Zhang , Xiao-Qi Zhou , Tao Yang , Jian-Wei Pan

Weak measurements are a new tool for characterizing post-selected quantum systems during their evolution. Weak measurement was originally formulated in terms of von Neumann interactions which are practically available for only the simplest…

Quantum Physics · Physics 2009-11-11 J. S. Lundeen , K. J. Resch

We derive a tight bound between the quality of estimating a quantum state by measurement and the success probability of undoing the measurement in arbitrary dimensional systems, which completely describes the tradeoff relation between the…

Quantum Physics · Physics 2012-10-12 Yong Wook Cheong , Seung-Woo Lee

In a weak measurement with post-selection, a measurement value, called the weak value, can be amplified beyond the eigenvalues of the observable. However, there are some controversies whether the weak value amplification is practically…

Quantum Physics · Physics 2015-09-30 Atsushi Nishizawa

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