Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session J05: Long-range or anisotropic interactions in cold gases |
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Chair: Don Fahey, University of Maryland Room: Wisconsin Center 102C |
Wednesday, May 29, 2019 10:30AM - 10:42AM |
J05.00001: Atom recoil during coherent light scattering from many atoms Francis Robicheaux, Shihua Huang The recoil momentum and energy of ultracold atoms is studied for situations where collective scattering or emission of photons is important. Effects due to the dipole-dipole interaction are emphasized. For two and many atoms confined in optical traps, calculations of the energy and momentum with respect to atomic separation are performed. When the atomic separation is comparable to or larger than the transition wavelength, the ultracold atoms’ recoil energy depends mainly on collective spontaneous decay rather than forces from the cooperative frequency shift. Calculations for a laser pulse reflecting from an atomic array suggest that the recoil energy of atoms can be substantially larger than might be expected from an independent atom picture. [Preview Abstract] |
Wednesday, May 29, 2019 10:42AM - 10:54AM |
J05.00002: Composite quasiparticles in strongly-correlated dipolar Fermi liquids Bilal Tanatar, Iran Seydi, Saeed H. Abedinpour, Reza Asgari Strong particle-plasmon interaction in electronic systems can lead to composite hole-plasmon excitations. We investigate the emergence of similar composite quasiparticles in ultracold dipolar Fermi liquids originating from the long-range dipole-dipole interaction. We use the $G_0W$ technique with an effective interaction obtained from the static structure factor to calculate the quasiparticle properties and single-particle spectral function. We first demonstrate that within this formalism a very good agreement with the quantum Monte Carlo results could be achieved over a wide range of coupling strengths for the renormalization constant and effective mass. The composite quasiparticle zero sound excitations which are undamped at long wavelengths emerge at intermediate and strong couplings in the spectral function and should be detectable through the radio frequency spectroscopy of nonreactive polar molecules at high densities. [Preview Abstract] |
Wednesday, May 29, 2019 10:54AM - 11:06AM |
J05.00003: Exploring a dipolar Luttinger liquid from the Tonks to the super-Tonks regimes Kuan-Yu Li, Wil Kao, Kuan-Yu Lin, Benjamin Lev A wide range of exotic quantum many-body phases and nonequilibrium dynamics may arise from the unusual properties of highly magnetic dysprosium confined to one dimension. We have previously explored the controlled breakdown of integrability in a dipolar quantum Newton's cradle created using the controllability of the dipolar interaction in 1D-confined dysprosium. Here, we report new work on exotic equilibrium properties of 1D dysprosium gases. We observe a dipolar confinement induced resonance and use it to create a dipolar Luttinger liquid in both the Tonks and super-Tonks regimes. We present results characterizing this resonance as well as collective oscillation measurements that reveal these regimes. [Preview Abstract] |
Wednesday, May 29, 2019 11:06AM - 11:18AM |
J05.00004: Transient supersolid properties in an array of dipolar quantum droplets Fabian Boettcher, Jan-Niklas Schmidt, Matthias Wenzel, Jens Hertkorn, Mingyang Guo, Tim Langen, Tilman Pfau We study theoretically and experimentally the emergence of supersolid properties in a dipolar Bose-Einstein condensate. The theory reveals a ground state phase diagram with three distinct regimes - a regular Bose-Einstein condensate, incoherent and coherent arrays of quantum droplets. The coherent droplets are connected by a finite superfluid density background, which leads - in addition to the periodic density modulation - to a robust phase coherence throughout the whole system. We further theoretically demonstrate that we are able to dynamically approach the ground state in our experiment and that its lifetime is only limited by three-body losses. Experimentally we probe and confirm the signatures of the phase diagram by observing the in-situ density modulation as well as the phase coherence using matter wave interference. [Preview Abstract] |
Wednesday, May 29, 2019 11:18AM - 11:30AM |
J05.00005: Exploring $np+np \rightarrow ns+(n+1)s$ dipole-dipole interactions with genetically optimized field ionization pulses Zhimin Cheryl Liu, Maia R. Rabinowitz, Miao Wang, Lauren Yoast, Thomas J. Carroll, Michael W. Noel With strong transition dipole moments, Rydberg atoms are able to exchange energy resonantly through long-range interactions. Often, selective field ionization (SFI) is used to obtain the atoms' state distribution after the interaction. In principle, SFI can map the binding energy of an atomic state to arrival time of the electron signal as atoms are ionized with a linearly increasing electric field ramp. However, the resolution of this technique is limited by the many Stark avoided crossings that are encountered as the field increases. We have previously developed ``directed field ionization'', a modification of SFI, which coherently manipulates the shape of time-resolved signal and thus improves the resolution\footnote{V. Gregoric \textit{et al.}, Phys. Rev. A \textbf{96}, 023403 (2017).}$^,$\footnote{V. Gregoric \textit{et al.}, Phys. Rev. A \textbf{98}, 063404 (2018).}. Here, we examine the $np+np \rightarrow ns+(n+1)s$ dipole-dipole interactions near $n =36$ using directed field ionization. With our technique, we quantify the state-distribution during the interaction and explore many-body effects. [Preview Abstract] |
Wednesday, May 29, 2019 11:30AM - 11:42AM |
J05.00006: Probing nonlocal correlations in quantum gases with ultra-long range Rydberg molecules Joseph Whalen, R. Ding, S. K. Kanungo, H. Y. Rathore, Y. Wang, F. B. Dunning, T. C. Killian, J. Sous, H. R. Sadeghpour, M. Wagner, R. Schmidt, S. Yoshida, J. Burdörfer Photo-excitation of ultra-long range Rydberg molecules (ULRRMs) provides a new, \textit{in situ} probe of spatial correlations in quantum gases at previously inaccessible length scales. Excitation of the ground-state dimer ULRRM measures the nonlocal pair correlation function $g^{(2)}(R)$, with $R$ tunable by changing the principal quantum number, $n$, of the target Rydberg state ($R\sim 2 n^2$). We present observations of the effects of quantum statistics, showing anti-bunching (Pauli exclusion) in a spin-polarized Fermi gas of $^{87}$Sr and bunching in a spinless Bose gas of $^{84}$Sr. We will also discuss measurement of the scattering wave function with ULRRM dimer excitation, which should display a node for internuclear separation equal to the s-wave scattering length. This length scale is accessible for resonant interactions such as between $^{84}$Sr and $^{88}$Sr ($a_{84-88}\sim1800\,a_0$). [Preview Abstract] |
Wednesday, May 29, 2019 11:42AM - 11:54AM |
J05.00007: The building principle of triatomic trilobite Rydberg molecules Peter Schmelcher, Christian Fey, Frederic Hummel We explore the properties of triatomic ultralong-range Rydberg molecules consisting of two ground state atoms and a highly excited Rydberg atom. Our focus is on molecular states for which the Rydberg electron is in a superposition of high angular momentum states whose probability densities resemble the form of trilobite fossils. The associated potential energy landscape has an oscillatory shape and supports a rich variety of stable geometries with different bond angles and bond lengths. Based on an electronic structure investigation we analyze the molecular geometry systematically and develop a simple building principle that predicts the triatomic equilibrium configurations. As a representative example we focus on $^{87}$Rb trimers correlated to the $n=30$ Rydberg state. Using an exact diagonalization scheme we determine and characterize localized vibrational states in these potential minima with energy spacings on the order of 100 MHz. [Preview Abstract] |
Wednesday, May 29, 2019 11:54AM - 12:06PM |
J05.00008: Optical signatures of long-ranged interactions between Rydberg excitons Valentin Walther, Thomas Pohl, Sjard Ole Krüger, Stefan Scheel, Julian Heckötter, Marc Aßmann, Manfred Bayer The excitation of semiconductor excitons to Rydberg states [1] opens up interesting opportunities to explore effects of strong correlations both on the excitonic level as well as in the optical response. Here, we calculate the interactions between such pairs of excitons in cuprous oxide [2], showing that van der Waals interactions are dominant in the low-density regime. These strong interactions can give rise to giant optical nonlinearities [3], which we evaluate by fully accounting for the excitons' coherences at low densities and which compare favorably with experiment. Finally, we demonstrate that pump-probe spectroscopy can provide detailed information about the nature of Rydberg exciton interactions. [1] T. Kazimierczuk, D. Fr\"{o}hlich, S. Scheel, H. Stolz {\&} M. Bayer, Nature 514, 343 (2014) [2] V. Walther, S. Kr\"{u}ger, S. Scheel {\&} T. Pohl, PRB 98, 165201 (2018) [3] V. Walther, J. Rohne {\&} T. Pohl, Nat. Comm. 9, 1309 (2018) [Preview Abstract] |
Wednesday, May 29, 2019 12:06PM - 12:18PM |
J05.00009: Rydberg blockade induced by a single ion Tilman Pfau, Felix Engel, Thomas Dieterle, Christian Tomschitz, Christian Veit, Nikolas Zuber, Thomas Schmid, Robert Löw, Florian Meinert Ultracold Rydberg atoms with their strong mutual interactions provide an interesting platform for e.g. quantum simulation or quantum information exploiting the so-called Rydberg blockade. A similar concept applies to hybrid systems of Rydberg atoms and ions leading to single charge-induced blockade phenomena over macroscopic distances. We demonstrate the excitation blockade of a single Rydberg atom by a single low-energy ion. The ion is produced from a single Rydberg excitation in an ultracold sample exploiting a novel optical two-photon ionization scheme, especially suited for the creation of very low-energy ions. We precisely control the ion's motion by applying small electric fields to analyze the blockade mechanism for a range of principal quantum numbers. Finally, we demonstrate the applicability of the ion as a high-sensitivity single-atom based electric field sensor. We use this method to determine the mobility of a cold ionic charge in a BEC. Our method may in the future also be used for controlling cold collisions, chemistry or charge mobilities in ion-atom mixtures. [1] Engel, F., Dieterle, T., Schmid, T., Tomschitz, C., Veit, C., Zuber, N., Low, R., Pfau, T., Meinert, F.: Observation of Rydberg Blockade Induced by a Single Ion. Phys. Rev. Lett. 121, 193401 (2018). [Preview Abstract] |
Wednesday, May 29, 2019 12:18PM - 12:30PM |
J05.00010: Hamiltonian engineering for studying many-body dynamics in strongly interacting Rydberg systems Nithiwadee Thaicharoen, Sebastian Geier, Titus Franz, Alexander M{\"u}ller, Andre Salzinger, Annika Tebben, Cl{\'e}ment Hainaut, Gerhard Z{\"u}rn, Matthias Weidem{\"u}ller Dipolar interacting Rydberg spin systems have been an ideal platform to study non-equilibrium phenomena of isolated quantum systems. Their tunable strong, long-range interactions provide new opportunities to investigate the dynamics of strongly correlated many-body quantum systems with beyond nearest-neighbor coupling. Here, the system can either relaxes to a thermal equilibrium or reaches nonthermal-fixed points, where effect of disorders, external fields and fluctuations play important roles [1]. In this work, we present an experimental realization of a dipolar spin-1/2 model by coupling two strongly interacting Rydberg states utilizing a microwave field. We propose a scheme to engineer the Hamiltonian of the system using dynamical pulse sequence of the microwave field to identify if the initial order of the system persist after time evolution of the system. The resulting global magnetization after the dynamics extracted from the systems utilizing a state-tomography technique and a selective ionization will be discussed.\\ \\ \noindent{[}1{]} A. Pi{\~n}eiro Orioli et al., PRL {\bf 120}, 063601 (2018) [Preview Abstract] |
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