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We present a hybrid quantum algorithm for estimating gaps in many-body energy spectra, supported by an analytic proof of its inherent resilience to state preparation and measurement errors, as well as mid-circuit multi-qubit depolarizing…

Quantum Physics · Physics 2025-02-14 Woo-Ram Lee , Nathan M. Myers , V. W. Scarola

We address the dephasing dynamics of the quantum Fisher information (QFI) for the process of quantum thermometry with probes coupled to squeezed thermal baths via the nondemolition interaction. We also calculate the upper bound for the…

Quantum Physics · Physics 2020-03-05 H. Rangani Jahromi

Quantum networks and remote quantum entanglement serve as vital future quantum communication resources with broad applicability. A key direction lies in extending the baseline of optical interferometers to enhance angular resolution in…

We develop a quantum metrological framework for resonant nanophotonic sensors based on subwavelength Fabry--Perot slit cavities. Building on classical Fisher-information analyses of resonant transmission sensors, we model parameter encoding…

Quantum Physics · Physics 2025-12-18 J. Sumaya-Martinez

We show that the decoherence, which in the long run destroys quantum features of a system, can be used to reveal the entanglement in a two-qubit system. To this end, we consider a criterion that formally resembles the…

Quantum Physics · Physics 2018-09-07 Jan Krzywda , Piotr Szańkowski , Jan Chwedeńczuk , Łukasz Cywiński

The long-lived, efficient storage and retrieval of a qubit encoded on a photon is an important ingredient for future quantum networks. Although systems with intrinsically long coherence times have been demonstrated, the combination with an…

Quantum Physics · Physics 2017-12-13 M. Körber , O. Morin , S. Langenfeld , A. Neuzner , S. Ritter , G. Rempe

In the noisy intermediate-scale quantum (NISQ) era, quantum error mitigation (QEM) is essential for producing reliable outputs from quantum circuits. We present a statistical signal processing approach to QEM that estimates the most likely…

In this paper, we introduce an efficient algorithm for the quantum amplitude estimation task which works in noisy intermediate-scale quantum(NISQ) devices. The quantum amplitude estimation is an important problem which has various…

Quantum Physics · Physics 2021-11-29 Kouhei Nakaji

The decoherence of a qubit due to a classical non-Gaussian noise with correlation time longer than the decoherence time is discussed for arbitrary working points of the qubit. A method is developed that allows an exact formula for the phase…

Superconductivity · Physics 2009-11-11 J. Bergli , Y. M. Galperin , B. L. Altshuler

Achieving quantum-enhanced performances when measuring unknown quantities requires developing suitable methodologies for practical scenarios, that include noise and the availability of a limited amount of resources. Here, we report on the…

The purport of quantum teleportation is to completely transfer information from one party to another distant partner. However, from the perspective of parameter estimation, it is the information carried by a particular parameter, not the…

Quantum Physics · Physics 2022-09-22 Xing Xiao , Yao Yao , Wo-Jun Zhong , Yan-Ling Li , Ying-Mao Xie

We address the metrological problem of estimating collective stochastic properties imprinted on a network of quantum sensors. Canonical examples include center-of-mass quadrature fluctuations in a system of bosonic modes and correlated…

Quantum Physics · Physics 2026-02-27 Anthony J. Brady , Yu-Xin Wang , Victor V. Albert , Alexey V. Gorshkov , Quntao Zhuang

We investigated the preservation of information encoded into the relative phase and amplitudes of optical pulses during storage and retrieval in an optical memory based on stimulated photon echo. By interfering photon echoes produced in a…

Quantum asymmetry is a physical resource which coincides with the amount of coherence between the eigenspaces of a generator responsible for phase encoding in interferometric experiments. We highlight an apparently counter-intuitive…

The measurement of physical parameters is one of the main pillars of science. A classic example is the measurement of the optical phase enabled by optical interferometry where the best sensitivity achievable with N photons scales as 1/N -…

Precision measurements with quantum systems rely on our ability to trace the differences between experimental signals to variations in unknown physical parameters. In this Letter we derive the Fisher information and the ensuing Cramer-Rao…

Quantum Physics · Physics 2015-06-17 Søren Gammelmark , Klaus Mølmer

Quantum sensing employs quantum resources of a sensor to attain a smaller estimation error of physical quantities than the limit constrained by classical physics. To measure a quantum reservoir, which is significant in decoherence control,…

Quantum Physics · Physics 2021-05-21 Wei Wu , Zhen Peng , Si-Yuan Bai , Jun-Hong An

Quantum illumination leverages entangled lights to detect the presence of low-reflectivity objects within a thermal environment. In a related vein, quantum parameter estimation utilizes nonclassical probes to precisely determine unknown…

Quantum Physics · Physics 2025-06-18 Wei Zhong , Dong-Qing Wang , Wen-Yi Zhu , Lan Zhou , Ming-Ming Du , Yu-Bo Sheng

The estimation of multi-qubit observables is a key task in quantum information science. The standard approach is to decompose a multi-qubit observable into a weighted sum of Pauli strings. The observable can then be estimated from…

Quantum Physics · Physics 2023-09-01 L. A. Markovich , J. Borregaard

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