Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session Y27: Light-Matter Interactions and General AMO Physics |
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Sponsoring Units: DAMOP Chair: Ryan T. Glasser, Tulane University Room: 290 |
Friday, March 17, 2017 11:15AM - 11:27AM |
Y27.00001: Competing role of Interactions in Synchronization of Exciton-Polariton condensates Saeed Khan, Hakan E. Tureci We present a theoretical study of synchronization dynamics in incoherently pumped exciton-polariton condensates in coupled traps~[1]. Our analysis is based on an expansion in non-Hermitian modes that take into account the trapping potential and the pump-induced complex-valued potential~[2]. We find that polariton-polariton and reservoir-polariton interactions play competing roles in the emergence of a synchronized phase as pumping power is increased, leading to qualitatively different synchronized phases. Crucially, these interactions can also act against each other to hinder synchronization. We present a phase diagram and explain the general characteristics of these phases using a generalized Adler equation. Our work sheds light on dynamics strongly influenced by competing interactions particular to incoherently pumped exciton-polariton condensates, which can lead to interesting features in recently engineered polariton lattices [3]. \\ \\ {[}1{]} S. Khan, H. E. Tureci, arXiv: 1610.04168 (2016) \\ {[}2{]} S. Khan, H. E. Tureci, arXiv: 1608.07557 (2016, to appear in Phys. Rev. A) \\ {[}3{]} F. Baboux \emph{et. al.}, Phys. Rev. Lett. 116, 066402 (2016) \\ [Preview Abstract] |
Friday, March 17, 2017 11:27AM - 11:39AM |
Y27.00002: Thermo-optically induced interactions in photon Bose-Einstein Condensates Hadiseh Alaeian, Clara Bartels, Martin Weitz Bose-Einstein condensation (BEC), a new state of matter, emerges when the de Broglie wavelength of bosons becomes larger than the particle separation, leading to a macroscopic occupation of the system ground state. Followed by the first experimental demonstrations of BEC in cold atomic gases, this phase transition has been observed in other bosonic gases, as polaritons and phonons. The most recent one, photon BEC, is a promising candidate for a new generation of coherent photon sources. Due to their infancy, however, many of their properties are still unknown or only partly explored. In this talk I will present my latest results on the implications of photon interactions in photon BECs. In particular, I will investigate the effect of a thermo-optic non-linearity, leading to spatially non-local and delayed interactions. Starting from the steady state behavior, I will explore the spectrum of elementary excitations as a small perturbation. Moreover, I will discuss the resulting effective photon dispersion, manifesting various properties including possible superfluidity, as well as roton and maxon modes. The implications of physical parameters as absorption, number of photons in the condensate, and cavity trap on the dispersion will be discussed. The results of this study shed new light on the implication of interactions in photonic many-body systems. [Preview Abstract] |
Friday, March 17, 2017 11:39AM - 11:51AM |
Y27.00003: Spatially multimode four-wave mixing for optical mode transformation Onur Danaci, Christian Rios, Ryan Glasser Spatially non-Gaussian states of light have applications to a variety of optical communications schemes and quantum optical experiments. Most methods used to generate such spatial modes either require linear optical elements that lead to significant attenuation, or rely on spatial-light modulators that are susceptible to damage at high optical powers. Here we demonstrate the ability of non-degenerate, non-collinear four-wave mixing (4WM) to generate non-Gaussian spatial modes of light, in which an input optical mode is amplified and converted to a particular spatial mode. Simultaneously, a second optical mode is created that propagates in a separate spatial direction, with a similarly non-Gaussian spatial profile. We show that the two resultant output non-Gaussian modes are well-approximated by modeling the 4WM interaction as a gain-aperture medium. Additionally, we combine this modeling with the phase-matching conditions imposed by the nonlinear 4WM process, and show that the resultant mode profiles agree with the experimental data, for both the output mode profiles, as well as their spatial Fourier Transforms. These results show that amplifying media may be used as a form of spatial mode conversion for optical states. [Preview Abstract] |
Friday, March 17, 2017 11:51AM - 12:03PM |
Y27.00004: Fast Light, Slow Light and Causality: Four Wave Mixing in Potassium Vapor Jon Swaim, Ryan Glasser The propagation of information in dispersive media has been of wide interest to the physics community, due to its relevance in information technologies as well as fundamental physics such as special relativity and causality. In particular, experiments involving anomalous dispersion have demonstrated optical pulses with group velocities greater than the speed of light in vacuum, or negative. In this work, we study fast and slow light phenomena associated with optical pulses generated via four wave mixing in hot potassium vapor. The relatively small ground state splitting of potassium combined with Doppler broadening produces overlapping atomic resonances, resulting in spectral reshaping of optical pulses that is due to a combination of gain and absorption in the medium. We show that superluminal or subluminal group velocities can be obtained, depending on the choice of experimental parameters. Furthermore, we also investigate the causal connection between abrupt (or non-analytic) features introduced into the input pulse and the resulting features observed after the four wave mixing process, in an attempt to show that information causality is preserved. [Preview Abstract] |
Friday, March 17, 2017 12:03PM - 12:15PM |
Y27.00005: Tunable self-healing optical state generation via atomic vapor Erin Knutson, Jon Swaim, Kaitlyn David, Christian Rios, Onur Danaci, Ryan Glasser Non-Gaussian beams, such as Bessel-Gauss beams, have been shown to display self-healing after encountering an obstruction. We show that tunable non-Gaussian, partially self-healing optical modes may be produced via nonlinear interactions between light and alkali atomic vapor. A Gaussian beam is focused into hot rubidium vapor and tuned to frequencies near the atomic resonances. The resulting spatially non-Gaussian output may be controlled either by adjusting the atom temperature or the input beam power. Additionally, these modes demonstrate a degree of self-reconstruction after encountering an obstruction in the beam path, which we find to be similar to that of a truncated Bessel-Gauss mode. We show that the output mode shape, as well as the enabled tunability, ultimately result from a complex interplay of various self-action effects in the atomic vapor. The extent of self-healing is also shown to be tunable in beam power and temperature, which we optimize for the reconstruction of a non-Gaussian beam that has encountered a physical obstruction at its center. Our findings indicate that tunable, non-Gaussian light generated via atomic vapor may be useful in experiments involving near-resonant light-atom interactions, as well as to optical communication and imaging schemes. [Preview Abstract] |
Friday, March 17, 2017 12:15PM - 12:27PM |
Y27.00006: Whispering gallery modes in deformed microcavities via transformation optics Jung-Wan Ryu, Yushin Kim, Soo-Young Lee, Inbo Kim, Jae-Hyung Han, Heung-Sik Tae, Muhan Choi, Bumki Min In dielectric cavities with rotational symmetry, very long-lived modes, so called Whispering Gallery Modes (WGMs), can be formed by total internal reflection. The ultra-high Q-factor of WGMs is of great merit in cutting-edge photonic devices, however their isotropic emission due to the rotational symmetry is a serious drawback in applications requiring directional light sources. Here, we have shown that, utilizing transformation optics, optical mode properties such as Q-factor and emission directionality can be tailored at will. The Q-spoiling problem inevitably involved for emission directionality is resolved by restoring WGMs in two dimensional deformed dielectric cavities. The restored WGMs retain the ultra-high Q factor even in considerably deformed cavities and exhibit the emission directionality as well. [Preview Abstract] |
Friday, March 17, 2017 12:27PM - 12:39PM |
Y27.00007: Physical meaning of the radial index of Laguerre-Gauss beams William Plick, Mario Krenn The Laguerre-Gauss modes are a class of fundamental and well-studied optical fields. These stable shape invariant photons, exhibiting circular-cylindrical symmetry, are familiar from laser optics, micromechanical manipulation, quantum optics, communication, and foundational studies in both classical optics and quantum physics. They are characterized, chiefly, by two mode numbers: the azimuthal index indicating the orbital angular momentum of the beam, which itself has spawned a burgeoning and vibrant subfield, and the radial index, which up until recently has largely been ignored. In this presentation we demonstrate a differential operator formalism for dealing with the radial modes in both the position and momentum representations and, more importantly, give the meaning of this quantum number in terms of a well-defined physical parameter: the intrinsic hyperbolic momentum charge. [Preview Abstract] |
Friday, March 17, 2017 12:39PM - 12:51PM |
Y27.00008: Quantum Nonlinear Optics without Photons Vincenzo MacrÃ¬ Here we propose a physical process analogous to spontaneous parametric down-conversion, where one excited atom directly transfers its excitation to a couple of spatially separated atoms with probability approaching one. The interaction is mediated by the exchange of virtual rather than real photons. This nonlinear optical process is coherent and reversible, so that the couple of excited atoms can transfer back the excitation to the first one: the analogous for atoms of sum-frequency generation. The parameters used here correspond to experimentally-demonstrated values in circuit QED. This approach can be expanded to consider other nonlinear inter-atomic processes as the four-qubit mixing and is an attractive architecture for the realization of quantum devices on a chip. [Preview Abstract] |
Friday, March 17, 2017 12:51PM - 1:03PM |
Y27.00009: Monte Carlo calculation of bound states in quantum mechanics: singular potentials Urs Gerber, James P Edwards, Christian Schubert, Maria Anabel Trejo, Axel Weber In continuation of the talk by M. A. Trejo at this conference, here we focus on the complications caused by singular potentials in a direct Monte Carlo calculation of the path integral representing the propagator in quantum mechanics. A naive time-discretization here usually leads to the unacceptable appearance of exceptional trajectories that dominate in the statistical average. We present a smoothing procedure that remedies this problem, and demonstrate its effectiveness for the case of the Coulomb potential. Finally, we briefly outline an extension of the method to the calculation of bound states in scalar field theory. [Preview Abstract] |
Friday, March 17, 2017 1:03PM - 1:15PM |
Y27.00010: On the evaluation of the absolute photon energy of Cu$ K\alpha _{\mathrm{,}}\beta $ lines using 4-crystal X --ray spectrometer Yoshiaki Ito, Tatsunori Tochio, Sei Fukushima A 4-crystal X-ray spectrometer was designed based on a 2-crystal X-ray spectrometer to be able to perform the absolute measurement of Bragg angle. This basic thought based on 2 crystals dates back to the times to A.Compton etc.[ Sci.Rev.Inst.,\textbf{2},365(1931), Phys.Rev.\textbf{47},882(1935) ]. Because a distortion to give the crystal by the adhesive when a crystal was glued, greatly affected the X-rays profile, we changed it to the channel cut crystal without a free distortion as for having made each crystal of 2-crystal a channel cut. The influence of the foot in the spectral profile is more suppressed because four times of reflections reflect it. It is a high resolution so as not to need to consider instrumental function by the reflection degree that a specific atomic analysis can be executed with the chemical state which it is possible for making the placement of the 4-crystal ($+$,$+)$ setting [Phys.Rev.\textbf{49},14(1936), Phys.Rev.A65,042502(2002)]. This type of spectrum device is first time in the world. Because the absolute measurement of 2$\theta $ angles is enabled by ($+$,-) and ($+$,$+)$ setting from the center of gravity position of the rocking curve and the center of gravity position of the X-rays spectrum, we may measure the absolute value of the X-ray photon energy. Because we evaluated the energy of the Cu $K\alpha $,$\beta $ lines, we report it. [Preview Abstract] |
Friday, March 17, 2017 1:15PM - 1:27PM |
Y27.00011: The natural line widths, asymmetric indices, and CK transitions in Ca to Ge Y. Ito, T. Tochio, H. Ohashi, M. Yamashita, S. Fukushima, M. Polasik, K. Slabkowska, L. Syrocki, E. Szymanska, J. Rzadkiewicz, P. Indelicato, J. Marques, M. Martins, J. Santos, F. Parente We have investigated systematically the $K\alpha_{\mathrm{1,2}}$ spectra in elements Ca to Ge using a high-resolution anti-parallel double-crystal X-ray spectrometer in order to elucidate the physical meaning of the asymmetry in the spectral profile. Lowe \textit{et al}. [PRA83, 060501] reported that the [\textit{1s3d}] shake-off probability for Sc at 42 {\%}, whichis the highest reported value. Chantler \textit{et al}. [J. Phys. B46, 015002] concluded that the symmetric profile of the observed Ti $K\alpha_{\mathrm{1}}$ emission line is different from the results of the Cu $K\alpha_{\mathrm{1,2}}$ obtained by Deutsch \textit{et al}.[ PRA51, 283]. To shed some light on this issue, we focused on the implications of the inclusion of the main [\textit{1s3d}] shake processes, asymmetric index, and natural line widths in 3$d$ elements. Our experimental results yielded the [\textit{1s3p}, \textit{3d}] shake probability for the 3d elements. For the [\textit{1s3p, 3d}] shake probability on Sc, we have obtained experimentally and theoretically (MCDF and the sudden approximation) the values \textasciitilde 25{\%} and 10{\%}, respectively. In both approaches, it is found that the shake-off related peaks appear between the $K\alpha_{\mathrm{1}}$ and $K\alpha _{\mathrm{2}}$ lines. Moreover, the observed Sc $K\alpha _{\mathrm{1\thinspace }}$line approaches a symmetric profile, unlike the another 3d's $K\alpha_{\mathrm{1}}$ line profile. The asymmetry index of $K\alpha_{\mathrm{1}}$ in 3$d$ elements from Sc to Zn is ascribed to the 3$d$ spectator hole. [Preview Abstract] |
Friday, March 17, 2017 1:27PM - 1:39PM |
Y27.00012: Quantum Nonlinear Optics without real Photons. Vincenzo MACR\'{I}, Anton Frisk Kockum, Roberto Stassi, Omar Di Stefano, Salvatore Savasta, Franco Nori We propose a physical process analogous to spontaneous parametric down-conversion, where one excited atom directly transfers its excitation to a couple of spatially-separated atoms with probability approaching one. The interaction is mediated by the exchange of virtual, rather than real, photons. This nonlinear optical process is coherent and reversible, so that the two excited atoms can transfer back the excitation to the first one: the~atomic analogue of sum-frequency~generation. The parameters used here correspond to experimentally-demonstrated values in circuit QED. ~This approach can be extended to consider other nonlinear interatomic processes, e.g. four-qubit mixing, and is an attractive architecture for the realization of quantum devices on a chip. [Preview Abstract] |
Friday, March 17, 2017 1:39PM - 1:51PM |
Y27.00013: Quantum correlations of light due to a room temperature mechanical oscillator Hendrik Schuetz, Vivishek Sudhir, Ryan Schilling, Sergey Fedorov, Dalziel Wilson, Tobias Kippenberg The coupling of laser light to a mechanical oscillator via radiation pressure leads to the emergence of quantum mechanical correlations in the amplitude and phase quadrature of the laser beam. To date, these quantum correlations have only been observed in a handful of cryogenic cavity optomechanical experiments. Utilizing a high-cooperativity near-field optomechanical system, together with variational measurement of the transmitted light, we demonstrate the ability to efficiently resolve quantum correlations imprinted on an optical laser beam interacting with a room temperature nanomechanical oscillator. Direct measurement of the optical beam in a detuned homodyne detector at frequencies far from the resonance frequency of the oscillator, reveal quantum correlations at a few percent level. This measurement fosters the rise of optomechanical systems as a room temperature platform for quantum enhanced metrology and paves the road for the first observation of ponderomotive squeezing under room temperature conditions. [Preview Abstract] |
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