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We propose a high-precision phase estimation scheme in a hybrid interferometer by synergistically combining a Kerr nonlinear phase shifter and multi-photon subtraction operations. Using a coherent state and a vacuum state as input…

Quantum Physics · Physics 2026-05-21 Lifen Guo , Qingqian Kang , Zekun Zhao , Jifeng Sun , Teng Zhao , Cunjin Liu , Xin Su , Liyun Hu

We analyze the ultimate bounds on the phase sensitivity of an interferometer, given the constraint that the state input to the interferometer's initial 50:50 beamsplitter $B$ is a product state of the two input modes. Requiring a product…

Quantum Physics · Physics 2014-09-17 Matthias D. Lang , Carlton M. Caves

Achieving the ultimate quantum precision in the estimation of multiple physical parameters simultaneously is a challenge in quantum metrology due to fundamental limitations and experimental challenges in harnessing the necessary quantum…

Quantum Physics · Physics 2025-06-24 Atmadev Rai , Danilo Triggiani , Paolo Facchi , Vincenzo Tamma

We study the sensitivity of a Mach-Zehnder interferometer that contains in addition to the phase shifter a non-linear element. By including both elements in a cavity or a loop that the light transverses many times, a non-linear kicked…

Quantum Physics · Physics 2022-08-31 Sabrina Müller , Daniel Braun

Photon addition operations applied to squeezed states have been shown to significantly enhance phase sensitivity. In this study, we extend this approach by applying photon addition not only to coherent states but also within a Mach--Zehnder…

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

We present a dispersive quantum thermometry protocol for simultaneous estimation of inverse temperature $\beta$ and interaction strength $x$ using a nonlinear Mach-Zehnder interferometer coupled to a thermal ancilla. We derive closed-form…

In this letter, we show that for all the so-called path-symmetric states, the measurement of parity of photon number at the output of an optical interferometer achieves maximal phase sensitivity at the quantum Cramer-Rao bound. Such optimal…

Quantum Physics · Physics 2015-08-25 Sejong Kim , Kaushik P. Seshadreesan , Jonathan P. Dowling , Hwang Lee

The sensitivity properties of an SU(1,1) interferometer made of two cascaded parametric amplifiers, as well as of an ordinary SU(2) interferometer preceded by a squeezer and followed by an anti-squeezer, are theoretically investigated.…

Quantum Physics · Physics 2017-02-22 Mathieu Manceau , Farid Khalili , Maria Chekhova

We theoretically analyze a Mach-Zehnder interferometer with trapped condensates, and find that it is surprisingly stable against the nonlinearity induced by inter-particle interactions. The phase sensitivity, which we study for number…

Quantum Physics · Physics 2011-08-17 Julian Grond , Ulrich Hohenester , Joerg Schmiedmayer , Augusto Smerzi

We optimize the signal-to-noise ratio of a Mach-Zehnder atom interferometer with Gaussian squeezed input states, in the presence interactions. For weak interactions, our results coincide with Phys. Rev. Lett. {\bf 100}, 250406 (2008), with…

Quantum Gases · Physics 2015-05-19 Igor Tikhonenkov , Michael G. Moore , Amichay Vardi

Fisher information, lies at the heart of parameter estimation theory, was recently found to have a close relation with multipartite entanglement (Pezz\'{e} and Smerzi, Phys. Rev. Lett. 102, 100401). We use Fisher information to distinguish…

Quantum Physics · Physics 2009-05-05 Jian Ma , Xiaoguang Wang

We report a theoretical and experimental study on the role of indistinguishability in the estimation of an interferometric phase. In particular, we show that the quantum Fisher information, which limits the maximum precision achievable in…

Quantum Physics · Physics 2020-01-01 Laura T. Knoll , Gustavo M. Bosyk , Ignacio H. López Grande , Miguel A. Larotonda

Optimal measurement scheme with an efficient data processing is important in quantum-enhanced interferometry. Here we prove that for a general binary outcome measurement, the simplest data processing based on inverting the average signal…

Quantum Physics · Physics 2014-07-11 X. M. Feng , G. R. Jin , W. Yang

We investigate the parameter estimation problem in a two-qubit system, in which each qubit is independently interacting with its Markovian environment. We study in detail the sensitivity of the estimation on the decoherence rate $\gamma$…

Quantum Physics · Physics 2014-01-14 Zheng Qiang , Yao Yao , Yong Li

We derive upper bounds on the quantum Fisher information in interferometry with $N$ subsystems, e.g. two-level atoms or Gaussian modes, in the presence of arbitrarily correlated Gaussian dephasing including independent and collective…

Quantum Physics · Physics 2014-03-06 Katarzyna Macieszczak

Atom interferometers are reaching sensitivities fundamentally constrained by quantum fluctuations. A main challenge is to integrate entanglement into quantum sensing protocols to enhance precision while ensuring robustness against noise and…

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

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

We characterize operationally meaningful quantum gains in a paradigmatic model of lossless multiple-phase interferometry and stress insufficiency of the analysis based solely on the concept of quantum Fisher information. We show that the…

Quantum Physics · Physics 2022-01-28 Wojciech Gorecki , Rafal Demkowicz-Dobrzanski

We study a nonlinear interferometer consisting of two consecutive parametric amplifiers, where all three optical fields (pump, signal and idler) are treated quantum mechanically, allowing for pump depletion and other quantum phenomena. The…

Quantum Physics · Physics 2018-12-27 Jefferson Flórez , Enno Giese , Davor Curic , Lambert Giner , Robert W. Boyd , Jeff S. Lundeen