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We propose a quantum process tomography scheme that utilizes two-mode squeezed vacuum to realize the parameter estimation with Heisenberg scaling. The objective is to estimate a rotating angle of polarization and parity detection is used as…

Quantum Physics · Physics 2018-06-27 Jian-Dong Zhang , Zi-Jing Zhang , Long-Zhu Cen , Yuan Zhao

We study the entanglement between the two beams exiting a Mach-Zehnder interferometer fed by a couple of squeezed-coherent states with arbitrary squeezing parameter. The quantum correlations at the output are function of the internal…

Quantum Physics · Physics 2009-10-31 Matteo G. A. Paris

We derive the form of the quantum filter equation describing the continuous observation of the phase of a quantum system in an arm of an interferometer via non-demolition measurements when the statistics of an input field used for the…

Quantum Physics · Physics 2016-01-19 John Gough

We experimentally demonstrate a new measurement scheme for the discrimination of two coherent states. The measurement scheme is based on a displacement operation followed by a photon number resolving detector, and we show that it…

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

We investigate interferometric techniques to estimate the deflection angle of an optical beam and compare them to the direct detection of the beam deflection. We show that quantum metrology methods lead to a unifying treatment for both…

Quantum Physics · Physics 2020-08-12 S. P. Walborn , G. H. Aguilar , P. L. Saldanha , L. Davidovich , R. L. de Matos Filho

The reconstruction of density matrices from measurement data (quantum state tomography) is the most comprehensive method for assessing the accuracy and performance of quantum devices. Existing methods to reconstruct two-photon density…

Quantum Physics · Physics 2025-03-12 Salini Rajeev , Mayukh Lahiri

We find a large class of pure and mixed input states with which the phase estimation precision saturates the Cramer-Rao bound under the compound measurements of parity and particle number. We further propose a quantum-phase-estimation…

Quantum Physics · Physics 2019-04-23 Haijun Xing , Libin Fu , Su Yi

After a derivation of the quantum Bayes theorem, and a discussion of the reconstruction of the unknown state of identical spin systems by repeated measurements, the main part of this paper treats the problem of determining the unknown phase…

Quantum Physics · Physics 2009-11-11 Filippo Neri

Imaging based on the induced coherence effect makes use of photon pairs to obtain information of an object without detecting the light that probes it. While one photon illuminates the object, only its partner is detected, so no measurement…

Quantum metrology overcomes standard precision limits by exploiting collective quantum superpositions of physical systems used for sensing, with the prominent example of non-classical multiphoton states improving interferometric techniques.…

We analyze in details a scheme for cloning of Gaussian states based on linear optical components and homodyne detection recently demonstrated by U. L. Andersen et al. [PRL 94 240503 (2005)]. The input-output fidelity is evaluated for a…

Quantum Physics · Physics 2009-11-13 Stefano Olivares , Matteo G. A. Paris , Ulrik L. Andersen

We present a quantum interference phenomenon in which four-photon quantum states generated by two independent sources are used to create a two-photon interference pattern without detecting two of the photons. Contrary to the common…

Quantum Physics · Physics 2025-09-26 Chandler Tarrant , Mayukh Lahiri

We introduce a scheme for linear optics quantum computation, that makes no use of teleported gates, and requires stable interferometry over only the coherence length of the photons. We achieve a much greater degree of efficiency and a…

Quantum Physics · Physics 2007-05-23 Daniel E. Browne , Terry Rudolph

The development of new techniques to improve measurements is crucial for all sciences. By employing quantum systems as sensors to probe some physical property of interest allows the application of quantum resources, such as coherent…

Quantum Physics · Physics 2019-05-15 G. H. Aguilar , M. A. de Souza , R. M. Gomes , J. Thompson , M. Gu , L. C. Céleri , S. P. Walborn

We estimate the quantum state of a light beam from results of quantum homodyne tomography noisy measurements performed on identically prepared quantum systems. We propose two Bayesian nonparametric approaches. The first approach is based on…

Statistics Theory · Mathematics 2016-10-07 Zacharie Naulet , Eric Barat

It is not clear if the performance of a quantum lidar or radar, without an idler and only using Gaussian resources, could exceed the performance of a semiclassical setup based on coherent states and homodyne detection. Here we prove this is…

Quantum Physics · Physics 2022-01-07 Gaetana Spedalieri , Stefano Pirandola

The measurement of the position-momentum EPR correlations of a two-photon state is important for many quantum information applications ranging from quantum key distribution to coincidence imaging. However, all the existing techniques for…

Quantum Physics · Physics 2022-09-28 Abhinandan Bhattacharjee , Nilakantha Meher , Anand K. Jha

Direct measurement of quantum non-Gaussianity requires some variant of a discrete photon-resolving detection, which is feasible only for low mean photon numbers. For a large mean photon number, intensity detection by linear photodiodes…

Quantum Physics · Physics 2025-10-22 Éva Rácz , László Ruppert , Radim Filip

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 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
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