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Quantum metrology employs quantum resources to achieve measurement precision beyond classical limits. This work investigates a Mach--Zehnder interferometer incorporating a Kerr nonlinear phase shifter, with photon-added two-mode squeezed…

Quantum Physics · Physics 2026-02-20 Zekun Zhao , Qingqian Kang , Teng Zhao , Cunjin Liu , Xin Su , Liyun Hu

Multiple-phase estimation exploiting quantum states has broad applications in novel sensing and imaging technologies. However, the unavoidable presence of lossy environments in practical settings often diminishes the precision of phase…

Quantum Physics · Physics 2025-07-23 Min Namkung , Dong-Hyun Kim , Seongjin Hong , Changhyoup Lee , Hyang-Tag Lim

A nonlinear phase shift is introduced to a Mach-Zehnder interferometer (MZI), and we present a scheme for enhancing the phase sensitivity. In our scheme, one input port of a standard MZI is injected with a coherent state and the other input…

Quantum Physics · Physics 2020-10-29 Gao-Feng Jiao , Keye Zhang , L. Q. Chen , Weiping Zhang , Chun-Hua Yuan

We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the…

Quantum Physics · Physics 2010-07-20 Hugo Cable , Gabriel A. Durkin

We address the performance of an interferometric setup in which a squeezed single photon interferes at a beam splitter with a coherent state. Our analysis in based on both the quantum Fisher information and the sensitivity when a…

Quantum Physics · Physics 2018-02-09 Stefano Olivares , Maria Popovic , Matteo G. A. Paris

We propose an interferometric scheme where each photon returns one bit of the binary expansion of an unknown phase. It sets up a method for estimating the phase value at arbitrary uncertainty. This strategy is global, since it requires no…

Quantum Physics · Physics 2025-04-23 Simone Roncallo , Xi Lu , Lorenzo Maccone

Quantum interferometry uses quantum resources to improve phase estimation with respect to classical methods. Here we propose and theoretically investigate a new quantum interferometric scheme based on three-dimensional waveguide devices.…

Quantum Physics · Physics 2013-01-09 N. Spagnolo , L. Aparo , C. Vitelli , A. Crespi , R. Ramponi , R. Osellame , P. Mataloni , F. Sciarrino

We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure…

We develop general tools to characterise and efficiently compute relevant observables of multimode $N$-photon states generated in non-linear decays in one-dimensional waveguides. We then consider optical interferometry in a Mach-Zender…

Quantum Physics · Physics 2020-02-19 M. Perarnau-Llobet , A. González-Tudela , J. I. Cirac

Understanding the fundamental limits on the precision to which an optical phase can be estimated is of key interest for many investigative techniques utilized across science and technology. We study the estimation of a fixed optical phase…

Quantum Physics · Physics 2017-12-13 Patrick M. Birchall , Jeremy L. O'Brien , Jonathan C. F. Matthews , Hugo Cable

Determining the phase in one arm of a quantum interferometer is discussed taking into account the three non-ideal aspects in real experiments: non-deterministic state preparation, non-unitary state evolution due to losses during state…

Quantum Physics · Physics 2015-05-20 Thomas B. Bahder

We consider the phase sensing via weak optical coherent state at quantum limit precision. A new detection scheme for the phase estimation is proposed which is inspired by the suboptimal quantum measurement in coherent optical communication.…

Quantum Physics · Physics 2016-09-28 Shuro Izumi , Masahiro Takeoka , Kentaro Wakui , Mikio Fujiwara , Kazuhiro Ema , Masahide Sasaki

Quantum metrology has an important role in the fields of quantum optics and quantum information processing. Here we introduce a kind of non-Gaussian state, Laguerre excitation squeezed state as input of traditional Mach-Zehnder…

Quantum Physics · Physics 2023-05-24 Zekun Zhao , Huan Zhang , Yibing Huang , Liyun Hu

Recent advances in quantum photonics have enabled increasingly robust protocols in optical phase estimation, achieving precisions beyond the standard quantum limit and approaching the Heisenberg limit. While intrinsic losses hinder the…

We investigate phase estimation in a lossy interferometer using entangled coherent states, with particular focus on a scenario where no reference beam is employed. By calculating the quantum Fisher information, we reveal two key results:…

Quantum Physics · Physics 2025-06-02 Jun Tang , Dong-Qing Wang , Wei Zhong , Lan Zhou , Yu-Bo Sheng

We address precision of optical interferometers fed by Gaussian states and involving passive and/or active elements, such as beam splitters, photodetectors and optical parametric amplifiers. We first address the ultimate bounds to precision…

Quantum Physics · Physics 2016-03-23 Carlo Sparaciari , Stefano Olivares , Matteo G. A. Paris

Geometric phase may enable inherently fault-tolerant quantum computation. However, due to potential decoherence effects, it is important to understand how such phases arise for {\it mixed} input states. We report the first experiment to…

A recently proposed phase-estimation protocol that is based on measuring the parity of a two-mode squeezed-vacuum state at the output of a Mach-Zehnder interferometer shows that Cram\'{e}r-Rao bound sensitivity can be obtained [P.\ M.\…

Quantum Physics · Physics 2013-09-10 Keith R. Motes , Petr M. Anisimov , Jonathan P. Dowling

We show that injecting a light pulse prepared in the Shroedinger cat quantum state into the dark port of a two-arm interferometer and the strong classical light into the bright one, it is possible, in principle, to detect a given phase…

Quantum Physics · Physics 2024-05-29 V. L. Gorshenin

We quantitatively investigate phase measurement in a Mach-Zehnder interferometer (MZI), which is injected with a weak coherent and a squeezed vacuum generated from a spontaneous parametric down-conversion. The measured three-photon…

Quantum Physics · Physics 2023-09-19 Lifeng Duan