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Tang Y, Dhar HS, Oulton RF, Nyman RA, Mintert F. Breakdown of Temporal Coherence in Photon Condensates. PHYSICAL REVIEW LETTERS 2024; 132:173601. [PMID: 38728729 DOI: 10.1103/physrevlett.132.173601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 03/20/2024] [Indexed: 05/12/2024]
Abstract
The temporal coherence of an ideal Bose gas increases as the system approaches the Bose-Einstein condensation threshold from below, with coherence time diverging at the critical point. However, counterexamples have been observed for condensates of photons formed in an externally pumped, dye-filled microcavity, wherein the coherence time decreases rapidly for increasing particle number above threshold. This Letter establishes intermode correlations as the central explanation for the experimentally observed dramatic decrease in the coherence time beyond critical pump power.
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Affiliation(s)
- Yijun Tang
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Himadri S Dhar
- Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Rupert F Oulton
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Robert A Nyman
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Florian Mintert
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
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Singh MK, Datta S. Dual measurements of temporal and spatial coherence of light in a single experimental setup using a modified Michelson interferometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:105109. [PMID: 34717416 DOI: 10.1063/5.0041438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
An experimental technique is developed to simultaneously measure both temporal and spatial coherences of a light source by altering a standard Michelson interferometer, which has been primarily used for measuring temporal coherence only. Instead of using simple plane mirrors, two retroreflectors and their longitudinal and lateral movements are utilized to incorporate spatial coherence measurement using this modified Michelson interferometer. In general, one uses Young's double slit interferometer to measure spatial coherence. However, this modified interferometer can be used as an optical setup kept at room temperature outside a cryostat to measure the spatiotemporal coherence of a light source placed at cryogenic temperatures. This avoids the added complexities of modulation of interference fringe patterns due to single slit diffraction as well. The process of mixing of spatial and temporal parts of coherences is intrinsic to existing methods for dual measurements. We addressed these issues of spatiotemporal mixing, and we introduced a method of "temporal filtering" in spatial coherence measurements. We also developed a "curve overlap" method that is used to extend the range of the experimental setup during temporal coherence measurements without compromising the precision. Together, these methods provide major advantages over plane mirror based standard interferometric systems for dual measurements in avoiding systematic errors, which lead to inaccuracies, especially for light sources with low coherences.
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Affiliation(s)
- Mohit Kumar Singh
- Department of Physics & Centre for Energy Science, Indian Institute of Science Education and Research, Pune 411008, Maharashtra, India
| | - Shouvik Datta
- Department of Physics & Centre for Energy Science, Indian Institute of Science Education and Research, Pune 411008, Maharashtra, India
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Rodrigues JD, Dhar HS, Walker BT, Smith JM, Oulton RF, Mintert F, Nyman RA. Learning the Fuzzy Phases of Small Photonic Condensates. PHYSICAL REVIEW LETTERS 2021; 126:150602. [PMID: 33929251 DOI: 10.1103/physrevlett.126.150602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
Phase transitions, being the ultimate manifestation of collective behavior, are typically features of many-particle systems only. Here, we describe the experimental observation of collective behavior in small photonic condensates made up of only a few photons. Moreover, a wide range of both equilibrium and nonequilibrium regimes, including Bose-Einstein condensation or laserlike emission are identified. However, the small photon number and the presence of large relative fluctuations places major difficulties in identifying different phases and phase transitions. We overcome this limitation by employing unsupervised learning and fuzzy clustering algorithms to systematically construct the fuzzy phase diagram of our small photonic condensate. Our results thus demonstrate the rich and complex phase structure of even small collections of photons, making them an ideal platform to investigate equilibrium and nonequilibrium physics at the few particle level.
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Affiliation(s)
- João D Rodrigues
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Himadri S Dhar
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Benjamin T Walker
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
- Centre for Doctoral Training in Controlled Quantum Dynamics, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Jason M Smith
- Department of Materials, University of Oxford, Oxford OX2 6NN, United Kingdom
| | - Rupert F Oulton
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Florian Mintert
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
| | - Robert A Nyman
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, United Kingdom
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Walker BT, Ash BJ, Trichet AAP, Smith JM, Nyman RA. Bespoke mirror fabrication for quantum simulation with light in open-access microcavities. OPTICS EXPRESS 2021; 29:10800-10810. [PMID: 33820206 DOI: 10.1364/oe.422127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 06/12/2023]
Abstract
In this work, we use focused ion beam (FIB) milling to generate custom mirror shapes for quantum simulation in optical microcavities. In the paraxial limit, light in multimode optical microcavities follows an equation of motion which is equivalent to Schrödinger's equation, with the surface topography of the mirrors playing the role of the potential energy landscape. FIB milling allows us to engineer a wide variety of trapping potentials for microcavity light, through exquisite control over the mirror topography, including 2D box, 1D waveguide, and Mexican hat potentials. The 2D box potentials are sufficiently flat over tens of microns, that the optical modes of the cavity, found by solving Schrödinger's equation on the measured cavity topography, are standing-wave modes of the box, rather than localised to deviations. The predicted scattering loss due to surface roughness measured using atomic force microscopy is found to be 177 parts per million, which corresponds to a cavity finesse of 2.2 × 104 once other losses have been taken into account. Spectra from dye-filled microcavities formed using these features show thermalised light in flat 2D potentials close to dye resonance, and spectrally-resolved cavity modes at the predicted frequencies for elliptical potentials. These results also represent a first step towards realising superfluid light and quantum simulation in arbitrary-shaped optical microcavities using FIB milling.
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Kurtscheid C, Dung D, Busley E, Vewinger F, Rosch A, Weitz M. Thermally condensing photons into a coherently split state of light. Science 2019; 366:894-897. [PMID: 31727840 DOI: 10.1126/science.aay1334] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/23/2019] [Accepted: 10/23/2019] [Indexed: 11/02/2022]
Abstract
The quantum state of light plays a crucial role in a wide range of fields, from quantum information science to precision measurements. Whereas complex quantum states can be created for electrons in solid-state materials through mere cooling, optical manipulation and control builds on nonthermodynamic methods. Using an optical dye microcavity, we show that photon wave packets can be split through thermalization within a potential with two minima subject to tunnel coupling. At room temperature, photons condense into a quantum-coherent bifurcated ground state. Fringe signals upon recombination show the relative coherence between the two wells, demonstrating a working interferometer with the nonunitary thermodynamic beam splitter. Our energetically driven optical-state preparation method provides a route for exploring correlated and entangled optical many-body states.
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Affiliation(s)
- Christian Kurtscheid
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany.
| | - David Dung
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Erik Busley
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Frank Vewinger
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Achim Rosch
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Cologne, Germany
| | - Martin Weitz
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany.
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