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Weak measurement is a standard measuring procedure with two changes: it is performed on pre- and post-selected quantum systems and the coupling to the measuring device is weakened. The outcomes of weak measurements, ``weak values'' are very…

High Energy Physics - Theory · Physics 2009-09-25 Lev Vaidman

In this article, we study quantum coherence of bipartite state from the perspective of weak measurement, which generalizes the notion of coherence relative to measurement. The is being illustrated by computing coherence for the well-known…

Quantum Physics · Physics 2023-04-06 Indrajith V. S , R. Muthuganesan , R. Sankaranarayanan

From its very beginning quantum theory has been revealing extraordinary and counter-intuitive phenomena, such as wave-particle duality, Schr\"odinger cats and quantum non-locality. In the study of quantum measurement, a process involving…

We propose a state preparation protocol based on sequential measurements of a central spin coupled with a spin ensemble, and investigate the usefulness of the generated multi-spin states for quantum enhanced metrology. Our protocol is shown…

Quantum Physics · Physics 2025-01-15 T. B. Lantaño , Dayou Yang , K. M. R. Audenaert , S. F. Huelga , M. B. Plenio

Quantum metrology with nonclassical states offers a promising route to improved precision in physical measurements. The quantum effects of Schr{\"o}dinger-cat superpositions or entanglements allow measurement uncertainties to reach below…

Quantum Physics · Physics 2025-07-11 Y. A. Yang , W. -T. Luo , J. -L. Zhang , S. -Z. Wang , Chang-Ling Zou , T. Xia , Z. -T. Lu

The emergence of realistic properties is a key problem in understanding the quantum-to-classical transition. In this respect, measurements represent a way to interface quantum systems with the macroscopic world: these can be driven in the…

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

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

We observe a metrological advantage in phase-space sensitivity for photon-added cat and kitten states over their original forms, due to phase-space broadening from increased amplitude via photon addition, albeit with higher energy cost.…

Quantum Physics · Physics 2026-01-23 Arman , Prasanta K. Panigrahi

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 analyse the quantum Cheshire cat using contextuality theory, to see if this can tell us anything about how best to interpret this paradox. We show that this scenario can be analysed using the relation between three different…

Quantum Physics · Physics 2024-02-16 Jonte R. Hance , Ming Ji , Holger F. Hofmann

A recent analysis [quant-ph/0104062] suggests that weak measurements can be used to give observational meaning to counterfactual reasoning in quantum physics. A weak measurement is predicted to assign a negative unit population to a…

Quantum Physics · Physics 2016-09-08 Klaus Molmer

Measurement devices could benefit from entangled correlations to yield a measurement sensitivity approaching the physical Heisenberg limit. Building upon previous magnetometric work using pseudo-entangled spin states in solution-state NMR,…

This paper presents a substructural logic of sequents with very restricted exchange and weakening rules. It is sound with respect to sequences of measurements of a quantic system. A sound and complete semantics is provided. The semantic…

Quantum Physics · Physics 2023-07-19 Daniel Lehmann

Quantum metrology allows for a huge boost in the precision of parameters estimation. However, it seems to be extremely sensitive on the noise. Bound entangled states are states with large amount of noise what makes them unusable for almost…

Quantum Physics · Physics 2015-12-09 L. Czekaj , A. Przysiezna , M. Horodecki , P. Horodecki

We discuss the concept of connection states (or connection matrices) that describe posterior ensembles, post-selected according to the outcomes of a quantum measurement. Connection matrices allow one to obtain results of any weak and some…

Quantum Physics · Physics 2013-08-02 Abraham G. Kofman , Sahin K. Ozdemir , Franco Nori

One of the common conceptions of nature, typically derived from the experiences with classical systems, is that attributes of the matter coexist with the substance. In the quantum regime, however, the quantum particle itself and its…

Quantum Physics · Physics 2021-06-29 Yosep Kim , Dong-Gil Im , Yong-Su Kim , Sang-Wook Han , Sung Moon , Yoon-Ho Kim , Young-Wook Cho

We examine the results of the paper "Precision metrology using weak measurements", [Zhang, Datta, and Walmsley, arXiv:1310.5302] from a quantum state discrimination point of view. The Heisenberg scaling of the photon number for the…

Quantum Physics · Physics 2015-05-05 Andrew N. Jordan , Jeff Tollaksen , James E. Troupe , Justin Dressel , Yakir Aharonov

The maximally entangled states are excellent candidates for achieving Heisenberg-limited measurements in ideal quantum metrology, however, they are fragile against dissipation such as particle losses and their achievable precisions may…

Quantum Physics · Physics 2016-02-05 Jiahao Huang , Xizhou Qin , Honghua Zhong , Yongguan Ke , Chaohong Lee

The information-theoretic definition of quantum correlation, e.g., quantum discord, is measurement dependent. By considering the more general quantum measurements, weak measurements, which include the projective measurement as a limiting…

Quantum Physics · Physics 2015-04-13 Ming-Liang Hu , Heng Fan , Dong-Ping Tian