Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session S02: Focus Session: Nonclassical States of LightFocus Live Streamed
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Chair: Arne Schwettmann, Univ of Oklahoma Room: Ballroom 111 A |
Thursday, June 8, 2023 10:30AM - 11:00AM |
S02.00001: Setting Experimental Bounds on Entangled Two-Photon Absorption Cross Sections Invited Speaker: Kristen M Parzuchowski Two-photon absorption (2PA) is widely used in microscopy for deep, sub-cellular imaging. However, the efficiency of 2PA is limited by the properties of both the absorber and the excitation light. Entangled photon pairs produced via spontaneous parametric downconversion (SPDC) exhibit correlations in time and space that may improve the excitation efficiency relative to a classical laser. The most significant improvement is expected at low photon flux where isolated pairs interact with the absorber. In this regime, the rate of the entangled two-photon absorption (E2PA) process scales linearly with photon flux and the E2PA cross section. Despite over a decade of publications claiming to measure huge cross sections that suggest a quantum advantage exists of up to 10 orders of magnitude, recent work from multiple groups has shown strong counterevidence. |
Thursday, June 8, 2023 11:00AM - 11:30AM |
S02.00002: Progress in the assessment and certification of entangled two-photon absorption in organic compounds. Invited Speaker: Alfred U'Ren Recent investigations suggest that the use of non-classical states of light, such as entangled photon pairs, may open new and exciting avenues in experimental two-photon absorption spectroscopy. Despite several experimental studies of entangled two-photon absorption (eTPA), there is still a heated debate on whether eTPA has truly been observed. This interesting debate has arisen, mainly because it has been recently argued that single-photon-loss mechanisms, such as scattering or hot-band absorption may mimic the expected entangled-photon linear absorption behavior. |
Thursday, June 8, 2023 11:30AM - 11:42AM |
S02.00003: New entangled quantum light: photonic dimer laser Qihang Liu, Jung-Tsung Shen, Yao Zhou Laser has been widely utilized in various domains, including the excitation of molecules in fluorescence microscopy and the encoding of information in laser communication. Nonetheless, laser light consists of linear superpositions of Fock states of independent photons, which represents only one of the simplest forms of possible quantum photonic states. As many nonlinear optical processes are very inefficient, if photon-photon correlations could be created, nonlinear process efficiency can be improved by orders of magnitude. I will discuss a new type of coherent quantum light source that, instead of independent photons, outputs a coherent state of the photonic dimers. Photonic dimer is a pair of temporally and spatially entangled photons that exhibit a strong bunching correlation, which has been shown to improve the performance of two-photon excitation microscopy and optical quantum computing. |
Thursday, June 8, 2023 11:42AM - 11:54AM |
S02.00004: Collective Lamb Shift and Spontaneous Emission of a dense Atomic Gas Hanzhen Ma, Susanne F Yelin A long-studied open question is to find a comprehensive and general description of the collective Lamb shift and spontaneous emission rate in a many-body radiative system. Both decay and energy levels are modified due to the dipole-dipole interaction between the radiators. We introduce a method to theoretically study weakly-driven, low-excited ensembles of two-level atoms, and obtain an analytic description of the collective Lamb shift and collective decay rate via a self-consistent relation. We predict the dependency of these measurable quantities on system parameters such as the number density of radiators, the Rabi frequency and the detuning of the external driving field as well as shape and size of the sample. |
Thursday, June 8, 2023 11:54AM - 12:06PM |
S02.00005: Phonon signatures in photon correlations Magnus O Borgh, Ben S Humphries, Dale Green, Garth A Jones We show that the second-order, two-time correlation functions for phonons and photons emitted from a vibronic molecule in a thermal bath result in bunching and anti-bunching, respectively. Signatures relating to phonon exchange with the environment are revealed in photon-photon correlations. Our work opens the possibility of a new approach to the significant and long-standing controversy regarding the role of quantum coherence in energy transfer within molecular systems and offers new opportunities to investigate quantum effects in condensed-phase molecular systems. We show that by detecting individual photons and measuring correlations in the photon emission it is possible to identify genuine quantum effects of molecules within a thermal environment, whose signatures are inferred from photon-photon, phonon-phonon and cross-correlation functions. |
Thursday, June 8, 2023 12:06PM - 12:18PM |
S02.00006: Probing Quantum Nature of Quasi-Classical States in an Interferometric setting. Moslem Mahdavifar Using quasi-classical states (coherent states) from a continuous wave (CW) source, we have been able to observe purely quantum mechanical effects. Our approach is based on the uniform randomization of the temporal phase of these states in an interferometric setting. We call such states as Phased Randomized Coherent States (PRCSs). First, we experimentally realized two-photon bunching and its complementary Hong-Ou-Mandel (HOM) effect. Then, after this quantum signature, we extend the idea to the probe of the Bell inequality. We successfully observed the violation from the CHSH form of the inequality and hence confirmed the existence of entanglement through our approach. In these works, the only degree of freedom involved was polarization. However, we aimed afterwards to add orbital angular momentum (OAM) to this toolbox and examine if we can transfer quantum information using OAM through coherent states from a CW source. Once again, this approach correctly matched with theoretical predictions resulting in two-photon bunching experimentally. Therefore, we believe that quasi-classical states can be utilized to a more diverse set of experiments in the domain of quantum optics and quantum information. One main benefit of these states is their photon rate. They do not have any shortage in photon numbers and thus they do not face scalability problem as much as the other single-photon sources do. |
Thursday, June 8, 2023 12:18PM - 12:30PM |
S02.00007: Observation of the Mollow Triplet from an optically confined single atom Chang Hoong Chow, Boon Long Ng, Christian Kurtsiefer Resonance fluorescence spectrum of a two-level system consists of a single peak that evolves into a triplet structure, known as Mollow triplet, when it is driven by a radiation field above its saturation intensity. Particularly, photons originating from different peaks of the triplet show distinct photon correlations, allowing the fluorescence to be engineered as a useful light source for quantum information processing purposes. We experimentally study the fluorescence spectrum of an optically trapped single Rb-87 atom by exciting a closed two-level transition with a near-resonant laser at different powers. The second-order intensity correlation measurement demonstrates the photon anti-bunching characteristic from a single atom emission as well as the Rabi oscillation of the atom. We also measured the cross correlation between photons coming from the two opposite sidebands of the fluorescence spectrum when an off-resonant field is applied to the atom. The asymmetry in the timing correlation indicates that there is a preferred time-ordering for the photon emission process in the two sidebands. The cascaded generation of time-correlated fluorescence photons with a tunable frequency difference will be useful for quantum optics experiments and quantum communication protocols. |
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