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We investigate the phase sensitivity of a Mach-Zehnder interferometer using a special class of generalized coherent states constructed from generalized Heisenberg and deformed $su(1,1)$ algebras. These states, derived from a perturbed…

Quantum Physics · Physics 2025-11-03 N. E. Abouelkhir , A. Slaoui , R. Ahl Laamara

It is shown that the addition of down-converted photon pairs to coherent laser light enhances the N-photon phase sensitivity due to the quantum interference between components of the same total photon number. Since most of the photons…

Quantum Physics · Physics 2008-04-23 Takafumi Ono , Holger F. Hofmann

We study the measurement of the position of atoms as a means to estimate the relative phase between two Bose-Einstein condensates. First, we consider $N$ atoms released from a double-well trap, forming an interference pattern, and show that…

Quantum Gases · Physics 2015-05-20 Jan Chwedenczuk , Francesco Piazza , Augusto Smerzi

Optical quantum computing, as well as quantum communication and sensing technology based on quantum correlations are in preparation. These require photodiodes for the detection of about 10^16 photons per second with close to perfect quantum…

Quantum Physics · Physics 2026-02-16 Leif Albers , Jan-Malte Michaelsen , Roman Schnabel

Phase estimation, at the heart of many quantum metrology and communication schemes, can be strongly affected by noise, whose amplitude may not be known, or might be subject to drift. Here, we investigate the joint estimation of a phase…

Interferometers operating at or close to quantum limits of precision have found wide application in tabletop searches for physics beyond the standard model, the study of fundamental forces and symmetries of nature and foundational tests of…

Quantum Physics · Physics 2016-01-12 H. F. H. Cheung , Y. S. Patil , L. Chang , S. Chakram , M. Vengalattore

In a conventional atomic interferometer employing $N$ atoms, the phase sensitivity is at the standard quantum limit: $1/\sqrt{N}$. Using spin-squeezing, the sensitivity can be increased, either by lowering the quantum noise or via phase…

Quantum Physics · Physics 2020-06-24 Renpeng Fang , Resham Sarkar , Selim M. Shahriar

The working principles of linear optical quantum computing are based on photodetection, namely, projective measurements. The use of photodetection can provide efficient nonlinear interactions between photons at the single-photon level,…

Quantum Physics · Physics 2010-04-09 Hwang Lee , Pieter Kok , Colin P. Williams , Jonathan P. Dowling

A proposed phase-estimation protocol based on measuring the parity of a two-mode squeezed-vacuum state at the output of a Mach-Zehnder interferometer shows that the Cram\'{e}r-Rao sensitivity is sub-Heisenberg [Phys.\ Rev.\ Lett.\ {\bf104},…

Quantum Physics · Physics 2017-05-17 Zixin Huang , Keith R. Motes , Petr M. Anisimov , Jonathan P. Dowling , Dominic W. Berry

We propose quantum versions of the Bell-Ziv-Zakai lower bounds on the error in multiparameter estimation. As an application we consider measurement of a time-varying optical phase signal with stationary Gaussian prior statistics and a power…

Quantum Physics · Physics 2015-08-26 Dominic W. Berry , Mankei Tsang , Michael J. W. Hall , Howard M. Wiseman

The impossibility of perfectly discriminating non orthogonal quantum states imposes far-reaching consequences both on quantum and classical communication schemes. We propose and numerically analyze an optimized quantum receiver for the…

Quantum Physics · Physics 2015-04-02 Christian R. Müller , Christoph Marquardt

A central feature of quantum metrology is the possibility of Heisenberg scaling, a quadratic improvement over the limits of classical statistics. This scaling, however, is notoriously fragile to noise. While for some noise types it can be…

Quantum Physics · Physics 2022-06-08 Giulio Chiribella , Xiaobin Zhao

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

Quantum Fisher information (QFI) sets the ultimate precision of optical phase measurements and reveals multiphoton entanglement, but it is not accessible with conventional photodetection. We theoretically predict that a photodetector…

Mesoscale and Nanoscale Physics · Physics 2026-04-01 Evgenii Barts , Takahiro Morimoto , Naoto Nagaosa

Quantum metrology shows that by exploiting nonclassical resources it is possible to overcome the fundamental limit of precision found for classical parameter-estimation protocols. The scaling of the quantum Fisher information -- which…

Quantum Physics · Physics 2022-11-08 Louis Garbe , Obinna Abah , Simone Felicetti , Ricardo Puebla

The prequel to this work [Ng et al., Phys. Rev. A 93, 042121 (2016)] proposes the method of spectral photon counting to enhance noise spectroscopy with an optical interferometer. While the predicted enhancement over homodyne detection is…

Quantum Physics · Physics 2026-04-14 Xinyi Sui , Mankei Tsang

We propose a phase estimation protocol for optical interferometry that employs a probe state (containing on average n photons) obtained by squeezing each mode, separately, of a single photon path entangled Bell state. This scheme involves a…

Quantum Physics · Physics 2014-01-06 Jaspreet Sahota , Daniel F. V. James

Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars…

Atomic Physics · Physics 2015-01-05 Gar-Wing Truong , James D. Anstie , Eric F. May , Thomas M. Stace , Andre N. Luiten

A rigorous lower bound is obtained for the average resolution of any estimate of a shift parameter, such as an optical phase shift or a spatial translation. The bound has the asymptotic form k_I/<2|G|> where G is the generator of the shift…

Quantum Physics · Physics 2015-06-03 Michael J. W. Hall , Howard M. Wiseman

The Heisenberg limit is acknowledged as the ultimate precision limit in quantum metrology, traditionally implying that root mean square errors of parameter estimation decrease linearly with the time T of evolution and the number N of…

Quantum Physics · Physics 2025-10-13 Binke Xia , Jingzheng Huang , Yuxiang Yang , Guihua Zeng