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We study quantum phase sensing with an asymmetric two-mode entangled coherent state (ECS) in which the two local amplitudes have different values. We find the phenomenon of the asymmetry-enhanced phase sensing which the asymmetry can…

Quantum Physics · Physics 2023-05-26 Xiao-Tong Chen , Wang-Jun Lu , Yunlan Zuo , Rui Zhang , Ya-Feng Jiao , Le-Man Kuang

Quantum non-Gaussian states of light have fundamental properties that are essential for a multitude of applications in quantum technology. However, many of these features are difficult to detect using standard criteria due to optical losses…

In quantum illumination, various detection schemes have been proposed for harnessing remaining quantum correlations of the entanglement-based resource state. To this date, the only successful implementation in the microwave domain relies on…

Quantum Physics · Physics 2024-01-09 F. Kronowetter , M. Würth , W. Utschick , R. Gross , K. G. Fedorov

We present a new framework for imaging and sensing based on utilizing a quantum computer to coherently process quantum information in an electromagnetic field. We describe the framework, its potential to provide improvements in imaging and…

Quantum Physics · Physics 2026-02-06 Mohan Sarovar

The discrimination of non-orthogonal quantum states with reduced or without errors is a fundamental task in quantum measurement theory. In this work, we investigate a quantum measurement strategy capable of discriminating two coherent…

Quantum Physics · Physics 2010-10-12 Christoffer Wittmann , Ulrik L. Andersen , Gerd Leuchs

We employ quantum state discrimination theory to establish the ultimate limit for spoofing detection in electromagnetic signals encoded with random quantum states. Our analysis yields an analytical expression for the optimal bound, which we…

Traditionally, spectroscopy is performed by examining the position of absorption lines. However, at frequencies near the transition frequency, additional information can be obtained from the phase shift. In this work we consider the…

Quantum Physics · Physics 2016-06-14 Hossein T. Dinani , Manish K. Gupta , Jonathan P. Dowling , Dominic W. Berry

We discuss several methods for unambiguous state discrimination of N symmetric coherent states using linear optics and photodetectors. One type of measurements is shown to be optimal in the limit of small photon numbers for any N. For the…

Quantum Physics · Physics 2009-11-07 S. J. van Enk

It is widely accepted that the selection of measurement bases can affect the efficiency of quantum state estimation methods, precision of estimating an unknown state can be improved significantly by simply introduce a set of symmetrical…

Quantum Physics · Physics 2012-01-31 Chi Zhang , Guo-Yong Xiang , Yong-Sheng Zhang , Chuan-Feng Li , Guang-Can Guo

An optical transmitter irradiates a target region containing a bright thermal-noise bath in which a low-reflectivity object might be embedded. The light received from this region is used to decide whether the object is present or absent.…

Accurate phase estimation in the presence of unknown phase diffusive noise is a crucial yet challenging task in noisy quantum metrology. This problem is particularly interesting due to the detrimental impact of the associated noise. Here,…

Quantum Physics · Physics 2024-07-12 Jayanth Jayakumar , Monika E. Mycroft , Marco Barbieri , Magdalena Stobińska

Subtracting photons from a two-mode squeezed state is a well-known method to increase entanglement. We analyse different strategies of local photon subtraction from a two-mode squeezed state in terms of entanglement gain and success…

The hybrid interferometer integrating an optical parametric amplifier and a beam splitter has the potential to outperform the SU(1,1) interferometer. However, photon loss remains a critical limitation for practical implementation. To…

Quantum Physics · Physics 2025-10-21 Qisi Zhou , Tao Jiang , Qingqian Kang , Teng Zhao , Xin Su , Cunjin Liu , Liyun Hu

Dephasing is a main noise mechanism that afflicts quantum information, it reduces visibility, and destroys coherence and entanglement. Therefore, it must be reduced, mitigated, and if possible corrected, to allow for demonstration of…

Quantum Physics · Physics 2024-11-19 Zixin Huang , Cosmo Lupo

Accurately estimating the overlap between quantum states is a fundamental task in quantum information processing. While various strategies using distinct quantum measurements have been proposed for overlap estimation, the lack of…

Quantum Physics · Physics 2025-02-13 Hao Zhan , Ben Wang , Minghao Mi , Jie Xie , Liang Xu , Aonan Zhang , Lijian Zhang

Presence of harmful noise is inevitable in entanglement-enhanced sensing systems, requiring careful allocation of resources to optimize sensing performance in practical scenarios. We advocate a simple but effective strategy to improve…

Quantum Physics · Physics 2025-07-04 Allen Zang , Tian-Xing Zheng , Peter C. Maurer , Frederic T. Chong , Martin Suchara , Tian Zhong

Using numerical simulations, we explore generalized fusion measurements, extending them in three key ways. We incorporate ancilla-boosting and code-boosting to optimize fusion measurements, which may, but do not necessarily, correspond to…

Quantum Physics · Physics 2024-10-29 Frank Schmidt , Peter van Loock

Quantum imaging with undetected light has recently emerged as a technique in which quantum correlations and nonlinear interferometry are combined to decouple illumination and detection paths. This approach has been more recently extended…

Knowledge of optimal quantum measurements is important for a wide range of situations, including quantum communication and quantum metrology. Quantum measurements are usually optimised with an ideal experimental realisation in mind. Real…

Quantum Physics · Physics 2015-06-03 Erika Andersson

The scheme of optical imaging using scattering lens can provide a resolution beyond the classical optical diffraction limit with a coherent-state input. Nevertheless, due to the shot noise of the coherent state, the corresponding…

Quantum Physics · Physics 2021-04-20 Dong Li , Yao Yao