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The formalism of weak measurement in quantum mechanics has revealed profound connections between measurement theory, quantum foundations, and signal processing. In this paper, we develop a pointer-free derivation of superoscillations,…

Quantum Physics · Physics 2025-08-04 Mirco A. Mannucci

We demonstrate the conditional reversal of a weak (partial-collapse) quantum measurement on a photonic qubit. The weak quantum measurement causes a nonunitary transformation of a qubit which is subsequently reversed to the original state…

Quantum Physics · Physics 2015-05-13 Yong-Su Kim , Young-Wook Cho , Young-Sik Ra , Yoon-Ho Kim

We study the problem of quantum-state tomography under the assumption that the state of the system is close to pure. In this context, an efficient measurements that one typically formulates uniquely identify a pure state from within the set…

Quantum Physics · Physics 2016-05-11 Amir Kalev , Charles H. Baldwin , Ivan H. Deutsch

Characterizing quantum systems is a fundamental task that enables the development of quantum technologies. Various approaches, ranging from full tomography to instances of classical shadows, have been proposed to this end. However, quantum…

Quantum Physics · Physics 2025-06-16 Franz J. Schreiber , Jens Eisert , Johannes Jakob Meyer

We demonstrate a novel experimental technique for quantum-state tomography of the collective density matrix. It is based on measurements of the polarization of light, traversing the atomic vapor. To assess the technique's robustness against…

Quantum Physics · Physics 2025-08-29 Marek Kopciuch , Magdalena Smolis , Adam Miranowicz , Szymon Pustelny

A many-body atomic system coupled to quantized light is subject to weak measurement. Instead of coupling light to the on-site density, we consider the quantum backaction due to the measurement of matter-phase-related variables such as…

Quantum Physics · Physics 2017-02-27 Wojciech Kozlowski , Santiago F. Caballero-Benitez , Igor B. Mekhov

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

How does the quantum-to-classical transition of measurement occur? This question is vital for both foundations and applications of quantum mechanics. Here, we develop a new measurement-based framework for characterizing the classical and…

The correlation function in quantum systems plays a vital role in decoding their properties and gaining insights into physical phenomena. Its interpretation corresponds to the propagation of particle excitations between space-time, similar…

Quantum Physics · Physics 2024-05-14 Yuan Feng , Xi Chen , Yongcheng Ding

We employ the technique of weak measurement in order to enable preservation of teleportation fidelity for two-qubit noisy channels. We consider one or both qubits of a maximally entangled state to undergo amplitude damping, and show that…

Quantum Physics · Physics 2013-11-01 T. Pramanik , A. S. Majumdar

Quantum metrology offers an enhanced performance in experiments such as gravitational wave-detection, magnetometry or atomic clocks frequency calibration. The enhancement, however, requires a delicate tuning of relevant quantum features…

Quantum Physics · Physics 2013-07-25 Jan Kolodynski , Rafal Demkowicz-Dobrzanski

Recent efforts have applied quantum tomography techniques to the calibration and characterization of complex quantum detectors using minimal assumptions. In this work we provide detail and insight concerning the formalism, the experimental…

Quantum Physics · Physics 2009-09-29 A. Feito , J. S. Lundeen , H. Coldenstrodt-Ronge , J. Eisert , M. B. Plenio , I. A. Walmsley

Quantum computers promise significant speedups in solving problems intractable for conventional computers but, despite recent progress, remain limited in scaling and availability. Therefore, quantum software and hardware development heavily…

Quantum Physics · Physics 2023-11-08 Stefan Hillmich , Igor L. Markov , Robert Wille

The readings of a highly inaccurate "weak" quantum meter, employed to determine the value of a dichotomous variable $S$ without destroying the interference between the alternatives,may take arbitrary values. We show that the expected values…

Quantum Physics · Physics 2015-09-17 D. Sokolovski

A direct measurement protocol allows reconstructing specific elements of the density matrix of a quantum state without using quantum state tomography. However, the direct measurement protocols to date are primarily based on weak or strong…

Quantum Physics · Physics 2021-10-13 Tianfeng Feng , Changliang Ren , Xiaoqi Zhou

Weak values, obtained from weak measurements, attempt to describe the properties of a quantum system as it evolves from an initial to a final state, without practically altering this evolution. Trajectories can be defined from weak…

Quantum Physics · Physics 2015-07-09 Alex Matzkin

A new weak measurement procedure is introduced for finite samples which yields accurate weak values that are outside the range of eigenvalues and which do not require an exponentially rare ensemble. This procedure provides a unique…

Quantum Physics · Physics 2009-11-13 Jeff Tollaksen

Certification of quantum devices received from unknown providers is a primary requirement before utilizing the devices for any information processing task. Here, we establish a protocol for certification of a particular set of $d$-outcome…

Quantum Physics · Physics 2022-05-20 Debarshi Das , Ananda G. Maity , Debashis Saha , A. S. Majumdar

We discuss a quantum mechanical indirect measurement method to recover a position dependent Hamilton matrix from time evolution of coherent quantum mechanical states through an object. A mathematical formulation of this inverse problem…

Mathematical Physics · Physics 2016-06-21 Joonas Ilmavirta

We demonstrate a new type of weak measurement based on the dynamics of spontaneous emission. The pointer in our scheme is given by the Lorentzian distribution characterizing atomic exponential decay via emission of a single photon. We thus…

Quantum Physics · Physics 2013-07-16 Itay Shomroni , Orel Bechler , Serge Rosenblum , Barak Dayan