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Thekkadath GS, Mycroft ME, Bell BA, Wade CG, Eckstein A, Phillips DS, Patel RB, Buraczewski A, Lita AE, Gerrits T, Nam SW, Stobińska M, Lvovsky AI, Walmsley IA. Quantum-enhanced interferometry with large heralded photon-number states. npj Quantum Inf 2020; 6:10.1038/s41534-020-00320-y. [PMID: 34131511 PMCID: PMC8201641 DOI: 10.1038/s41534-020-00320-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 09/04/2020] [Indexed: 05/14/2023]
Abstract
Quantum phenomena such as entanglement can improve fundamental limits on the sensitivity of a measurement probe. In optical interferometry, a probe consisting of N entangled photons provides up to aN enhancement in phase sensitivity compared to a classical probe of the same energy. Here, we employ high-gain parametric down-conversion sources and photon-number-resolving detectors to perform interferometry with heralded quantum probes of sizes up to N = 8 (i.e. measuring up to 16-photon coincidences). Our probes are created by injecting heralded photon-number states into an interferometer, and in principle provide quantum-enhanced phase sensitivity even in the presence of significant optical loss. Our work paves the way towards quantum-enhanced interferometry using large entangled photonic states.
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Affiliation(s)
- G S Thekkadath
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - M E Mycroft
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - B A Bell
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - C G Wade
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - A Eckstein
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - D S Phillips
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - R B Patel
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - A Buraczewski
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - A E Lita
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - T Gerrits
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - S W Nam
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - M Stobińska
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - A I Lvovsky
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - I A Walmsley
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
- Department of Physics, Imperial College London, Prince Consort Rd, London SW7 2AZ, UK
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Downing CA, Sturges TJ, Weick G, Stobińska M, Martín-Moreno L. Topological Phases of Polaritons in a Cavity Waveguide. Phys Rev Lett 2019; 123:217401. [PMID: 31809145 DOI: 10.1103/physrevlett.123.217401] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Indexed: 06/10/2023]
Abstract
We study the unconventional topological phases of polaritons inside a cavity waveguide, demonstrating how strong light-matter coupling leads to a breakdown of the bulk-edge correspondence. We observe an ostensibly topologically nontrivial phase, which unexpectedly does not exhibit edge states. Our findings are in direct contrast to topological tight-binding models with electrons, such as the celebrated Su-Schrieffer-Heeger (SSH) model. We present a theory of collective polaritonic excitations in a dimerized chain of oscillating dipoles embedded inside a photonic cavity. The added degree of freedom from the cavity photons upgrades the system from a typical SSH SU(2) model into a largely unexplored SU(3) model. Tuning the light-matter coupling strength by changing the cavity size reveals three critical points in parameter space: when the polariton band gap closes, when the Zak phase changes from being trivial to nontrivial, and when the edge state is lost. These three critical points do not coincide, and thus the Zak phase is no longer an indicator of the presence of edge states. Our discoveries demonstrate some remarkable properties of topological matter when strongly coupled to light, and could be important for the growing field of topological nanophotonics.
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Affiliation(s)
- C A Downing
- Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza E-50009, Spain
| | - T J Sturges
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - G Weick
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France
| | - M Stobińska
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - L Martín-Moreno
- Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza E-50009, Spain
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Stobińska M, Buraczewski A, Moore M, Clements WR, Renema JJ, Nam SW, Gerrits T, Lita A, Kolthammer WS, Eckstein A, Walmsley IA. Quantum interference enables constant-time quantum information processing. Sci Adv 2019; 5:eaau9674. [PMID: 31334346 PMCID: PMC6641944 DOI: 10.1126/sciadv.aau9674] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 06/14/2019] [Indexed: 05/27/2023]
Abstract
It is an open question how fast information processing can be performed and whether quantum effects can speed up the best existing solutions. Signal extraction, analysis, and compression in diagnostics, astronomy, chemistry, and broadcasting build on the discrete Fourier transform. It is implemented with the fast Fourier transform (FFT) algorithm that assumes a periodic input of specific lengths, which rarely holds true. A lesser-known transform, the Kravchuk-Fourier (KT), allows one to operate on finite strings of arbitrary length. It is of high demand in digital image processing and computer vision but features a prohibitive runtime. Here, we report a one-step computation of a fractional quantum KT. The quantum d-nary (qudit) architecture we use comprises only one gate and offers processing time independent of the input size. The gate may use a multiphoton Hong-Ou-Mandel effect. Existing quantum technologies may scale it up toward diverse applications.
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Affiliation(s)
- M. Stobińska
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - A. Buraczewski
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - M. Moore
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - W. R. Clements
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - J. J. Renema
- Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
| | - S. W. Nam
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA
| | - T. Gerrits
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA
| | - A. Lita
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA
| | - W. S. Kolthammer
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - A. Eckstein
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - I. A. Walmsley
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
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