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Measurements are central in all quantitative sciences, and a fundamental challenge is to make observations without systematic measurement errors. This holds in particular for quantum information processing, where other error sources, such…

An extension to computational mechanics complexity measure is proposed in order to tackle quantum states complexity quantification. The method is applicable to any $n-$partite state of qudits through some simple modifications. A Werner…

Computational Physics · Physics 2011-10-28 Yuri Campbell , José Roberto Castilho Piqueira

Assessing the quality of an ensemble of noisy entangled states is a central task in quantum information processing. Usually this is done by measuring and hence destroying multiple copies, from which state tomography or fidelity estimation…

Quantum Physics · Physics 2023-02-14 Ferran Riera-Sàbat , Jorge Miguel-Ramiro , Wolfgang Dür

Quantum parameter estimation exploits quantum states to achieve estimation sensitivity beyond classical limit. In continuous variable (CV) regime, squeezed state has been exploited to implement deterministic phase estimation. It is however,…

Quantum Physics · Physics 2026-01-01 Sijin Li , Wei Wang

Quantum entanglement and squeezing have significantly improved phase estimation and imaging in interferometric settings beyond the classical limits. However, for a wide class of non-interferometric phase imaging/retrieval methods vastly…

In this paper, we investigate theoretically the back-action evading measurement of the collective mode of an interacting atomic Bose-Einstein condensate (BEC) trapped in an optical cavity which is driven coherently by a pump laser with a…

Quantum Physics · Physics 2020-04-22 M. Fani , A. Dalafi

We derive an explicit formula for an entanglement measure of mixed quantum states in a multi-level atom interacting with a cavity field within the framework of the quantum mutual entropy. We describe its theoretical basis and discuss its…

Quantum Physics · Physics 2007-05-23 Mahmoud Abdel-Aty , M. R. B. Wahiddin , A. -S. F. Obada

By using photon pairs created in parametric down conversion, we report on an experiment, which demonstrates that measurement can recover the quantum entanglement of two qubit system in a pure dephasing environment. The concurrence of the…

Quantum Physics · Physics 2010-12-22 Xiao-Ye Xu , Jin-Shi Xu , Chuan-Feng Li , Guang-Can Guo

In a quantum system that is bounded by past and future conditions, weak continuous monitoring forward-evolving and backward-evolving quantum states are usually carried out separately. Therefore, measured signals at a given time t cannot be…

Quantum Physics · Physics 2019-05-20 Le Bin Ho

We explore a two-node, entanglement-enhanced sensor network for differential phase sensing that exploits decoherence-free subspaces to suppress common-mode noise, a primary limitation of many state-of-the-art quantum sensors. We identify a…

The evolution of the quantum state of a system upon measurement results in state update. In this work, we investigate the characterization of updated states of multi-partite entangled qubit states with non-destructive weak measurements,…

Quantum Physics · Physics 2025-02-18 Jawad Allam , Alex Matzkin

We propose a critical dissipaive quantum metrology schemes for single parameter estimation which are based on a quantum probe consisting of coherently driven ensemble of $N$ spin-1/2 particles under the effect of squeezed, collective spin…

Quantum Physics · Physics 2023-08-16 Venelin P. Pavlov , Diego Porras , Peter A. Ivanov

We demonstrate in a superconducting qubit the conditional recovery ("uncollapsing") of a quantum state after a partial-collapse measurement. A weak measurement extracts information and results in a non-unitary transformation of the qubit…

Collective phenomena arise from interactions within complex systems, leading to behaviors absent in individual components. Observing quantum collective phenomena with macroscopic mechanical oscillators has been impeded by the stringent…

We propose a new class of probabilistic reversing operations on the state of a system that was disturbed by a weak measurement. It can approximately recover the original state from the disturbed state especially with an additional…

Quantum Physics · Physics 2010-09-01 Hiroaki Terashima , Masahito Ueda

Precise measurements are the key to advances in all fields of science. Quantum entanglement shows higher sensitivity than achievable by classical methods. Most physical quantities including position, displacement, distance, angle, and…

Quantum Physics · Physics 2017-07-05 Zhi-Yuan Zhou , Shi-Long Liu , Shi-Kai Liu , Yin-Hai Li , Dong-Sheng Ding , Guang-Can Guo , Bao-Sen Shi

We investigate optimal discrimination between two projective single-qubit measurements in a scenario where the measurement can be performed only once. We consider general setting involving a tunable fraction of inconclusive outcomes and we…

Quantum Physics · Physics 2014-12-01 M. Mikova , M. Sedlak , I. Straka , M. Micuda , M. Ziman , M. Jezek , M. Dusek , J. Fiurasek

Entanglement is an important quantum resource to achieve high sensitive quantum metrology. However, the rapid decoherence of quantum entangled states, due to the unavoidable environment noise, result in practically the unwanted sharp drop…

Quantum Physics · Physics 2023-06-21 X. N. Feng , D. He , L. F. Wei

In ``Distributed quantum sensing with mode-entangled spin-squeezed atomic states" Nature (2022), Malia et. al. claim to improve the precision of a network of clocks by using entanglement. In particular, by entangling a clock network with up…

Quantum Physics · Physics 2023-05-04 Liam P. McGuinness

The role of entanglement in determining the non-classicality of a given interaction has gained significant traction over the last few years. In particular, as the basis for new experimental proposals to test the quantum nature of the…

Quantum Physics · Physics 2023-11-15 A. Douglas K. Plato , Dennis Rätzel , Chuanqi Wan