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We study a sensor network of distributed Mach-Zehnder interferometers (MZIs) for the parallel (simultaneous) estimation of an arbitrary number $d \geq 1$ of phase shifts. The scheme uses a squeezed-vacuum state that is split between $d$…

Quantum Physics · Physics 2021-09-21 Marco Malitesta , Augusto Smerzi , Luca Pezzè

When standard light sources are employed, the precision of the phase determination is limited by the shot noise. Quantum entanglement provides means to exceed this limit with the celebrated example of N00N states that saturate the ultimate…

Quantum Physics · Physics 2010-06-01 M. Kacprowicz , R. Demkowicz-Dobrzanski , W. Wasilewski , K. Banaszek , I. A. Walmsley

Two path interferometry with coherent states and squeezed vacuum can achieve phase sensitivities close to the Heisenberg limit when the average photon number of the squeezed vacuum is close to the average photon number of the coherent…

Quantum Physics · Physics 2015-05-14 Takafumi Ono , Holger F. Hofmann

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

We propose an enhanced optical interferometer based on tailored non-classical light generated by nonlinear dynamics and projective measurements in a three-level atom cavity QED system. A coherent state in the cavity becomes dynamically…

Quantum Physics · Physics 2019-03-21 K. Gietka , T. Wasak , J. Chwedenczuk , F. Piazza , H. Ritsch

Precise phase measurements by interferometers are crucial in science for detecting subtle changes, such as gravitational waves. However, phase sensitivity is typically limited by the standard quantum limit (SQL) with uncorrelated particles…

We theoretically study the effect of quantum statistics of the light field on the quantum enhancement of parameter estimation based on cat state input the SU(1,1) interferometer. The phase sensitivity is dependent on the relative phase…

We analyze a quantum force sensor that uses coherent quantum noise cancellation (CQNC) to beat the Standard Quantum Limit (SQL). This sensor, which allows for the continuous, broad-band detection of feeble forces, is a hybrid dual-cavity…

Quantum Physics · Physics 2015-10-20 F. Bariani , H. Seok , S. Singh , M. Vengalattore , P. Meystre

In this paper, we show how the Robertson uncertainty relation gives certain intrinsic quantum limits of measurements in the most general and rigorous mathematical treatment. A general lower bound for the product of the root-mean-square…

Quantum Physics · Physics 2015-05-20 Masanao Ozawa

Quantum receiver is an important tool for overcoming the standard quantum limit (SQL) of discrimination errors in optical communication. We theoretically study the quantum receivers for discriminating ternary and quaternary phase shift…

We theoretically derive the lower and upper bounds of quantum Fisher information (QFI) of an SU(1,1) interferometer whatever the input state chosen. According to the QFI, the crucial resource for quantum enhancement is shown to be large…

Quantum Physics · Physics 2017-09-13 Qian-Kun Gong , Dong Li , Chun-Hua Yuan , Z. Y. Ou , Weiping Zhang

According to quantum theory the interactions between physical systems are quantized. As a direct consequence, measurement sensitivities are fundamentally limited by quantization noise, or just `quantum noise' in short. Furthermore,…

Quantum Physics · Physics 2017-12-19 Roman Schnabel

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

The Heisenberg uncertainty principle sets a lower bound on the sensitivity of continuous optical measurements of force. This bound, the standard quantum limit, can only be reached when a mechanical oscillator subjected to the force is…

Interferometry is a paradigm for most precision measurements. Using $N$ uncorrelated particles, the achievable precision for a two-mode (two-path) interferometer is bounded by the standard quantum limit (SQL), $1/\sqrt{N}$, due to the…

Quantum Gases · Physics 2018-07-05 Yi-Quan Zou , Ling-Na Wu , Qi Liu , Xin-Yu Luo , Shuai-Feng Guo , Jia-Hao Cao , Meng Khoon Tey , Li You

Quantum phase estimation protocols can provide a measuring method of phase shift with precision superior to standard quantum limit (SQL) due to the application of a nonclassical state of light. A squeezed vacuum state, whose variance in one…

Quantum Physics · Physics 2020-04-14 Juan Yu , Yue Qin , Jinliang Qin , Hong Wang , Zhihui Yan , Xiaojun Jia , Kunchi Peng

Probabilistic amplification through photon addition, at the output of an Mach-Zehnder interferometer is discussed for a coherent input state. When a metric of signal to noise ratio is considered, nondeterministic, noiseless amplification of…

Quantum computing using two optical coherent states as qubit basis states has been suggested as an interesting alternative to single photon optical quantum computing with lower physical resource overheads. These proposals have been…

Quantum Physics · Physics 2009-11-13 A. P. Lund , T. C. Ralph , H. L. Haselgrove

In this work, we investigate precision limitations in spectrophotometry (i.e., spectroscopic concentration measurements) imposed by chemical processes of molecules. Using the recently developed Photon-resolved Floquet theory, which…

Quantum Physics · Physics 2026-01-28 Georg Engelhardt , Dahai He , JunYan Luo

Interference of light fields plays an important role in various high-precision measurement schemes. It has been shown that super resolving phase measurements beyond the standard coherent state limit can be obtained either by using maximally…

Quantum Physics · Physics 2013-10-08 Emanuele Distante , Miroslav Jezek , Ulrik L. Andersen