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 J07: Spin-Orbit Coupling in Degenerate Gases |
Hide Abstracts |
Chair: Peter Engels, Washington State University Room: Wisconsin Center 103AB |
Wednesday, May 29, 2019 10:30AM - 10:42AM |
J07.00001: Experimental realization of density-dependent Peierls phases to couple dynamical gauge fields to matter Frederik Goerg, Kilian Sandholzer, Joaquin Minguzzi, Remi Desbuquois, Konrad Viebahn, Anne-Sophie Walter, Michael Messer, Tilman Esslinger The coupling between gauge and matter fields plays an important role in many models of high-energy and condensed matter physics. In these models, the gauge fields are dynamical degrees of freedom in the sense that they are influenced by the spatial configuration and motion of the matter field. So far, synthetic magnetic fields for ultracold atoms in optical lattices were intrinsically classical, as they did not feature any back-action from the atoms. We realize the fundamental ingredient for a density-dependent gauge field by engineering non-trivial Peierls phases that depend on the site occupation of fermions in a Hubbard dimer. Our method relies on breaking time-reversal symmetry by driving the optical lattice simultaneously at two frequencies which are resonant with the onsite interaction energy. We demonstrate a technique to quantify the amplitude of the resulting density-assisted tunneling matrix element and to directly measure its Peierls phase with respect to the single-particle hopping. The tunnel coupling features two distinct regimes which can be characterized by a Z2-invariant. Moreover, we provide a full tomography of the winding structure of the Peierls phase around a Dirac point that appears in the driving parameter space. Our experiments constitute the first step towards the quantum simulation of intractable problems in lattice gauge theories such as quantum electro- or chromodynamics. [Preview Abstract] |
Wednesday, May 29, 2019 10:42AM - 10:54AM |
J07.00002: Robust Weyl points in 1D superlattices with transverse spin-orbit coupling Xi-Wang Luo, Chuanwei Zhang Weyl points, synthetic magnetic monopoles in the 3D momentum space, are the key features of topological Weyl semimetals, which have been proposed to exist in cold-atom systems with spin-orbit coupling (SOC). Previous schemes usually rely on high-dimensional SOC requiring complex laser configurations and precise control of laser parameters. Here we propose that robust Wely points can be obtained using 1D triple-well superlattices (a spin-1/three-band system) with only 2D transverse SOC realized by Raman-assisted tunnelings. The presence of a third band is responsible to the robustness of the Weyl points against system parameters (e.g., Raman laser polarization, phase, incident angle, etc.). Different with a spin-1/2 system, the non-trivial topology of Weyl points in such spin-1 system is characterized by both the spin vector and tensor textures, which can be probed using momentum-resolved Rabi spectroscopy. Our proposal provide a simple yet powerful platform for exploring Weyl physics and related high-dimensional topological phenomena using high-spin ultracold atoms. [Preview Abstract] |
Wednesday, May 29, 2019 10:54AM - 11:06AM |
J07.00003: Topology of a two-dimensional spin-orbit coupled Bose gas Ana Valdes-Curiel, Dimitris Trypogeorgos, Qiyu Liang, Russell Anderson, Ian Spielman Spin-orbit coupling is a necessary ingredient in phenomena such as the quantum spin-Hall effect and topological insulators. We explore a new cold atom realization of two-dimensional spin- orbit coupling using far-detuned Raman transitions and a strong radio-frequency magnetic field, all within the ground state hyperfine manifold. We characterize the spin and momentum resolved dispersion relation using Fourier transform spectroscopy and observe a robust Dirac point that can be moved by changing the Raman power balance or detuning. Furthermore, using three arm “Ramsey” interferometer we detect a momentum dependent phase winding around the Dirac point and use it to calculate topological invariants. [Preview Abstract] |
Wednesday, May 29, 2019 11:06AM - 11:18AM |
J07.00004: Realization of three-dimensional nodal-line semimetal with ultracold fermions Chengdong HE, Bo Song, Sen Niu, Long Zhang, Zejian Ren, Entong Zhao, Xiong-Jun Liu, Gyu-Boong Jo Despite recent breakthroughs in topological bands for ultracold atoms in 1D and 2D, it has been an open challenge to realize and observe 3D topological matter in an atomic system. While numerous schemes have been proposed, the experimental complexity and the characterization of the 3D band structure acted as a barrier against experimental groups achieving this outstanding goal. In this talk, we report the realization and observation of 3D nodal-line semimetal band with spin-orbit-coupled ultracold fermions. The 3D topological band structure is achieved by stacking 2D Dirac semimetal in the $x$-$y$ plane along $z$ direction in Raman-dressed optical lattices. To detect 3D topological phases, we developed $k_z$ resolved spin texture measurement technique based on emergent magnetic group symmetry in our system. By directly imaging spin texture in specific $k_z$ plane with different Zeeman splitting, 3D nodal lines can be reconstructed. The realization of topological band structure is also verified in quench dynamics by detecting band inversion lines, which are bulk counterparts of Fermi arc states. This technique can be broadly applied to characterizing 3D topological states with similar symmetries. [Preview Abstract] |
Wednesday, May 29, 2019 11:18AM - 11:30AM |
J07.00005: A Bose-Einstein Condensate on a Synthetic Hall Cylinder Chuan-Hsun Li, Yangqian Yan, Sayan Choudhury, David B. Blasing, Qi Zhou, Yong P. Chen Interplay between matter and fields in physical spaces with nontrivial geometries can give rise to many unexpected phenomena. However, their realizations are often impeded by experimental constraints. Here, we realize a Bose-Einstein condensate (BEC) on a synthetic cylindrical surface subject to a net radial synthetic magnetic flux. This cylindrical surface comprises a real spatial dimension and a curved synthetic dimension formed by cyclically-coupled atomic spin states. The BEC on such a Hall cylinder has properties unattainable by its counterpart in a two-dimensional plane. We observe Bloch oscillations of the BEC with doubled periodicity of the band structure, analogous to traveling on a M\"{o}bius strip in momentum space, reflecting band crossings protected by a nonsymmorphic symmetry that underlines the emergent crystalline order in the BEC wavefunction. We further demonstrate such topological operations as gapping the band crossings and unzipping the cylinder. Our work opens the door to engineering synthetic gauge fields in synthetic curved spaces with nontrivial geometries and/or topologies and observing intriguing phenomena inherent to such spaces. [Preview Abstract] |
Wednesday, May 29, 2019 11:30AM - 11:42AM |
J07.00006: Spin-orbit coupling in a Bose-Fermi spinor Mixture Chuanzhou Zhu, Li Chen, Hui Hu, Xia-Ji Liu, Han Pu We consider a mixture of spin-1/2 bosons and fermions, where only the bosons are subjected to the spin-orbit coupling induced by Raman beams. The fermions, although not directly coupled to the Raman lasers, acquire an effective spin-orbit coupling through the spin-exchange interaction between the two species. Our calculation shows that this is a promising way of obtaining spin-orbit coupled Fermi gas without Raman-induced heating, which can lead to topological bands and/or topological fermionic superfluid. Furthermore, the presence of fermions have a striking effect on the stripe phase of the bosons --- the spatial period of the bosonic density stripes can be greatly increased which makes this phase easily observable in experiment. This system provides a new platform, not available in solid state materials, to study the physics of spin-orbit coupling. [Preview Abstract] |
Wednesday, May 29, 2019 11:42AM - 11:54AM |
J07.00007: Synthetic electromagnetic forces in ultracold atoms Benjamin Smith, Logan Cooke, Taras Hrushevskyi, Lindsay LeBlanc Employing the familiar Raman coupling scheme in a F$=$1 87Rb BEC, we explore the possibility of engineering a uniform artificial vector potential with periodic time-dependence in our experiments. By sinusoidally modulating the two-photon Raman detuning, we show how a uniform AC synthetic electric field emerges. Extending on this effect, we can introduce a static magnetic field gradient to produce an AC synthetic magnetic field, due to the curl of vector potential. In addition, we also study this system numerically by simulating the quasi-3D Gross-Pitaevskii equation. In this talk, I will discuss our recent progress, as well as exploring some of the similarities and differences between our results and those predicted by Maxwell's equations, particularly the effects of interactions. [Preview Abstract] |
Wednesday, May 29, 2019 11:54AM - 12:06PM |
J07.00008: How to dress radio-frequency photons with tunable momentum Boris Shteynas, Jeongwon Lee, Furkan Cagri Top, Jun-Ru Li, Alan O. Jamison, Gediminas Juzeliūnas, Wolfgang Ketterle We demonstrate how the combination of oscillating magnetic forces and radio-frequency (RF) pulses endows RF photons with tunable momentum. We observe velocity-selective spinflip transitions and the associated Doppler shift. This realizes the key component of purely magnetic spin-orbit coupling schemes for ultracold atoms, which does not involve optical transitions and therefore avoids the problem of heating due to spontaneous emission. [Preview Abstract] |
Wednesday, May 29, 2019 12:06PM - 12:18PM |
J07.00009: Optically induced hydrodynamics in a spin-orbit-coupled Bose-Einstein condensate Maren Mossman, Peter Engels The ability to coherently couple spin and momentum in a cold atom system via spin-orbit coupling has established a platform for novel Bose gas experiments. A key feature of spin-orbit coupling is the breaking of Galilean invariance in the system. Using an elongated Bose-Einstein condensate, we experimentally probe the hydrodynamic properties and excitations of this system by applying optical potentials such as localized barriers or potential dips. The experiments provide insight into the nonlinear excitation spectrum of the system and also have possible implications for applications in atomtronics and spintronics. The current status and future directions of this work are discussed. [Preview Abstract] |
Wednesday, May 29, 2019 12:18PM - 12:30PM |
J07.00010: Engineered dispersions in Spin-Orbit Coupled BECs Edward Delikatny, Michael Forbes, Peter Peter Engels, Maren Mossman Spin-Orbit Coupling (SOC) allows for a great deal of control over BECs. Using tunable dispersions we explore the effects of negative effective mass on commonly seen phenomenon like solitons, shockwaves, and phonons. By tuning the SOC parameters and initial cloud density in a tube geometry, one can control the formation, motion, and effective mass of phonons. We generate larger and larger phonons that lie outside of the linear regime using an optical bucket and compare their measured velocities to theory. We extend this work to investigate the generation and motion of solitons in a tube with spatially varying effective-detuning. This work is supported by the National Science Foundation under Grant No. 1707691. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700