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Abstract
A theoretical framework for the quantization of gravity has been an elusive Holy Grail since the birth of quantum theory and general relativity. While generations of scientists have attempted to find solutions to this deep riddle, an alternative path built upon the idea that experimental evidence could determine whether gravity is quantized has been decades in the making. The possibility of an experimental answer to the question of the quantization of gravity is of renewed interest in the era of gravitational wave detectors. We review and investigate an important subset of phenomenological quantum gravity, detecting quantum signatures of weak gravitational fields in table-top experiments and interferometers.
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Caspar P, Verbanis E, Oudot E, Maring N, Samara F, Caloz M, Perrenoud M, Sekatski P, Martin A, Sangouard N, Zbinden H, Thew RT. Heralded Distribution of Single-Photon Path Entanglement. PHYSICAL REVIEW LETTERS 2020; 125:110506. [PMID: 32975988 DOI: 10.1103/physrevlett.125.110506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
We report the experimental realization of heralded distribution of single-photon path entanglement at telecommunication wavelengths in a repeater-like architecture. The entanglement is established upon detection of a single photon, originating from one of two spontaneous parametric down-conversion photon pair sources, after erasing the photon's which-path information. In order to certify the entanglement, we use an entanglement witness which does not rely on postselection. We herald entanglement between two locations, separated by a total distance of 2 km of optical fiber, at a rate of 1.6 kHz. This work paves the way towards high-rate and practical quantum repeater architectures.
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Affiliation(s)
- P Caspar
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - E Verbanis
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - E Oudot
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
- Quantum Optics Theory Group, University of Basel, CH-4056 Basel, Switzerland
| | - N Maring
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - F Samara
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - M Caloz
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - M Perrenoud
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - P Sekatski
- Quantum Optics Theory Group, University of Basel, CH-4056 Basel, Switzerland
| | - A Martin
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - N Sangouard
- Quantum Optics Theory Group, University of Basel, CH-4056 Basel, Switzerland
- Institut de physique théorique, Université Paris Saclay, CEA, CNRS, F-91191 Gif-sur-Yvette, France
| | - H Zbinden
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
| | - R T Thew
- Department of Applied Physics, University of Geneva, CH-1211 Genève, Switzerland
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3
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Projective measurement onto arbitrary superposition of weak coherent state bases. Sci Rep 2018; 8:2999. [PMID: 29445101 PMCID: PMC5813249 DOI: 10.1038/s41598-018-21092-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/25/2018] [Indexed: 11/17/2022] Open
Abstract
One of the peculiar features in quantum mechanics is that a superposition of macroscopically distinct states can exist. In optical system, this is highlighted by a superposition of coherent states (SCS), i.e. a superposition of classical states. Recently this highly nontrivial quantum state and its variant have been demonstrated experimentally. Here we demonstrate the superposition of coherent states in quantum measurement which is also a key concept in quantum mechanics. More precisely, we propose and implement a projection measurement onto an arbitrary superposition of two weak coherent states in optical system. The measurement operators are reconstructed experimentally by a novel quantum detector tomography protocol. Our device is realized by combining the displacement operation and photon counting, well established technologies, and thus has implications in various optical quantum information processing applications.
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Guerreiro T, Monteiro F, Martin A, Brask JB, Vértesi T, Korzh B, Caloz M, Bussières F, Verma VB, Lita AE, Mirin RP, Nam SW, Marsilli F, Shaw MD, Gisin N, Brunner N, Zbinden H, Thew RT. Demonstration of Einstein-Podolsky-Rosen Steering Using Single-Photon Path Entanglement and Displacement-Based Detection. PHYSICAL REVIEW LETTERS 2016; 117:070404. [PMID: 27563941 DOI: 10.1103/physrevlett.117.070404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate the violation of an Einstein-Podolsky-Rosen steering inequality developed for single-photon path entanglement with displacement-based detection. We use a high-rate source of heralded single-photon path-entangled states, combined with high-efficiency superconducting-based detectors, in a scheme that is free of any postselection and thus immune to the detection loophole. This result conclusively demonstrates single-photon entanglement in a one-sided device-independent scenario, and opens the way towards implementations of device-independent quantum technologies within the paradigm of path entanglement.
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Affiliation(s)
- T Guerreiro
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - F Monteiro
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - A Martin
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - J B Brask
- Département de Physique Théorique, Université de Genève, CH-1211 Geneva 4, Switzerland
| | - T Vértesi
- Institute for Nuclear Research, Hungarian Academy of Sciences, H4001-Debrecen, P.O. Box 51, Hungary
| | - B Korzh
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - M Caloz
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - F Bussières
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - V B Verma
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - A E Lita
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - R P Mirin
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - S W Nam
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - F Marsilli
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA
| | - M D Shaw
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA
| | - N Gisin
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - N Brunner
- Département de Physique Théorique, Université de Genève, CH-1211 Geneva 4, Switzerland
| | - H Zbinden
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - R T Thew
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
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Vivoli VC, Barnea T, Galland C, Sangouard N. Proposal for an Optomechanical Bell Test. PHYSICAL REVIEW LETTERS 2016; 116:070405. [PMID: 26943515 DOI: 10.1103/physrevlett.116.070405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Indexed: 06/05/2023]
Abstract
Photons of a laser beam driving the upper motional sideband of an optomechanical cavity can decay into photon-phonon pairs by means of an optomechanical parametric process. The phononic state can subsequently be mapped to a photonic state by exciting the lower sideband, hence creating photon-photon pairs out of an optomechanical system. Here we show that these pairs can violate a Bell inequality when they are measured with photon counting techniques preceded by small displacement operations in phase space. The consequence of such a violation as well as the experimental requirements are intensively discussed.
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Affiliation(s)
- V Caprara Vivoli
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - T Barnea
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - C Galland
- Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - N Sangouard
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland
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Bruno N, Pini V, Martin A, Verma VB, Nam SW, Mirin R, Lita A, Marsili F, Korzh B, Bussières F, Sangouard N, Zbinden H, Gisin N, Thew R. Heralded amplification of photonic qubits. OPTICS EXPRESS 2016; 24:125-133. [PMID: 26832244 DOI: 10.1364/oe.24.000125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate postselection free heralded qubit amplification for Time-Bin qubits and single photon states in an all-fibre, telecom-wavelength, scheme that highlights the simplicity, stability and potential for fully integrated photonic solutions. Exploiting high-efficiency superconducting detectors, the gain, fidelity and the performance of the amplifier are studied as a function of loss. We also demonstrate the first heralded single photon amplifier with independent sources. This provides a significant advance towards demonstrating device-independent quantum key distribution as well as fundamental tests of quantum mechanics over extended distances.
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