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Augmenting a train of bright phase-modulated laser-light pulses of a coherent communications system with infinitesimally small quantum photons per pulse -- entangled across several time bins -- prepared by splitting squeezed light in a…

Quantum Physics · Physics 2025-11-04 Saikat Guha , Tiju Cherian John , Zihao Gong , Prithwish Basu

Homodyne measurement is a crucial tool widely used to address continuous variables for bosonic quantum systems. While an ideal homodyne detection provides a powerful analysis, e.g. to effectively measure quadrature amplitudes of light in…

Quantum Physics · Physics 2024-01-03 Jaehak Lee , Jiyong Park , Jaewan Kim , M. S. Kim , Hyunchul Nha

Traditional method for measuring continuous-variable quantum entanglement relies on balanced homodyne detections, which are sensitive to vacuum quantum noise coupled in through losses resulted from many factors such as detector's quantum…

Quantum Physics · Physics 2020-05-06 Jiamin Li , Yuhong Liu , Nan Huo , Liang Cui , Sheng Feng , Xiaoying Li , Z. Y. Ou

We address the limit of the Gaussian operations and classical communication in the problem of quantum state discrimination. We show that the optimal Gaussian strategy for the discrimination of the binary phase shift keyed (BPSK) coherent…

Quantum Physics · Physics 2009-11-13 Masahiro Takeoka , Masahide Sasaki

Low-noise, efficient, phase-sensitive time-domain optical detection is essential for foundational tests of quantum physics based on optical quantum states and the realization of numerous applications ranging from quantum key distribution to…

Quantum Physics · Physics 2013-07-18 Merlin Cooper , Christoph Söller , Brian J. Smith

When separated measurements on entangled quantum systems are performed, the theory predicts correlations that cannot be explained by any classical mechanism: communication is excluded because the signal should travel faster than light;…

Quantum Physics · Physics 2011-08-11 Daniel Cavalcanti , Nicolas Brunner , Paul Skrzypczyk , Alejo Salles , Valerio Scarani

In this paper, we propose to use the decoy-state technique to improve the security of the quantum key distribution (QKD) systems based on homodyne detection against the photon number splitting (PNS) attack. The decoy-state technique is a…

Quantum Physics · Physics 2017-11-28 S. Hamed Shams Mousavi , Philippe Gallion

Multimode Gaussian quantum light, which includes multimode squeezed and multipartite quadrature entangled light, is a very general and powerful quantum resource with promising applications in quantum information processing and metrology. In…

Quantum Physics · Physics 2013-05-30 Olivier Pinel , Julien Fade , Daniel Braun , Pu Jian , Nicolas Treps , Claude Fabre

Squeezed light is a crucial resource for continuous-variable (CV) quantum information science. Distributed multi-mode squeezing is critical for enabling CV quantum networks and distributed quantum sensing. To date, multi-mode squeezing…

Quantum communication aims to provide absolutely secure transmission of secret information. State-of-the-art methods encode symbols into single photons or coherent light with much less than one photon on average. For long distance…

We address binary optical communication channels based on phase-shift keyed coherent signals in the presence of phase diffusion. We prove theoretically and demonstrate experimentally that a discrimination strategy based on homodyne…

Quantum Physics · Physics 2015-06-16 Stefano Olivares , Simone Cialdi , Fabrizio Castelli , Matteo G. A. Paris

A self-homodyne detection scheme is proposed to perform two-mode tomography on a twin-beam state at the output of a nondegenerate optical parametric amplifier. This scheme has been devised to improve the matching between the local…

Quantum Physics · Physics 2009-10-31 Giacomo M. D'Ariano , Michael Vasilyev , Prem Kumar

Cross-correlation heterodyne detectors exhibit the potential for suppression of the detection quantum noise below shot noise without use of optical squeezing for capturing weak optical signals in low frequency bands. To understand the…

Quantum Physics · Physics 2022-11-09 Sheng Feng , Kaikai Wu

We assess the security of a quantum key distribution protocol relying on the transmission of Gaussian-modulated coherent states and homodyne detection. This protocol is shown to be equivalent to a squeezed state protocol based on a CSS code…

Quantum Physics · Physics 2009-11-10 S. Iblisdir , G. Van Assche , N. J. Cerf

We investigate localization of entanglement of multimode Gaussian states into a pair of modes by local Gaussian measurements on the remaining modes and classical communication. We find that for pure states and for mixed symmetric states…

Quantum Physics · Physics 2009-11-13 Jaromir Fiurasek , Ladislav Mista

In the standard homodyne configuration, an unknown optical state is combined with a local oscillator (LO) on a beam splitter (BS). Good quadrature measurements require a high-amplitude LO and two high-efficiency photodiodes whose signals…

Quantum Physics · Physics 2023-06-01 Arik Avagyan

In multimode optical systems, the spectral covariance matrix encodes all the information about quantum correlations between the quadratures of Gaussian states. Recent research has revealed that, in scenarios that are more common than…

Quantum Physics · Physics 2026-03-11 Bakhao Dioum , Virginia D'Auria , Giuseppe Patera

Quantum properties of light, which are crucial resources for Quantum Technologies, are quite fragile in nature and can be degraded and even concealed by the environment. We show, both theoretically and experimentally, that mesoscopic…

Quantum Physics · Physics 2021-10-13 Alessia Allevi , Maria Bondani

We describe a novel tool for the quantum characterization of optical devices. The experimental setup involves a stable reference state that undergoes an unknown quantum transformation and is then revealed by balanced homodyne detection.…

A new method is described for determining the quantum state of correlated multimode radiation by interfering the modes and measuring the statistics of the superimposed fields in four-port balanced homodyne detection. The full information on…

Quantum Physics · Physics 2009-10-30 T. Opatrny , D. -G. Welsch , W. Vogel