Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Z06: Synthetic Gauge Fields and Spin-Orbit Coupling in Bose and Fermi GasesLive
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Chair: Karina Jiménez Garcia, CINVESTAV - Querétaro |
Friday, June 4, 2021 10:30AM - 10:42AM Live |
Z06.00001: Strongly interacting bosons in a synthetic magnetic field Joyce Kwan, Sooshin Kim, Perrin C Segura, Robert Schittko, Julian Leonard, Markus Greiner The interplay between magnetic fields and interacting particles can lead to exotic phases of matter that exhibit topological order and high degrees of entanglement. Although these phases were discovered in a solid-state setting, recent innovations in systems of ultracold neutral atoms allow the synthesis of artificial magnetic fields. However, so far these experiments have mostly explored the regime of weak interactions, which precludes access to correlated many-body states. |
Friday, June 4, 2021 10:42AM - 10:54AM Live |
Z06.00002: Hall response and geometric squeezing of a degenerate Fermi gas Cedric Wilson, Airlia Shaffer, Parth B Patel, Zhenjie Yan, Biswaroop Mukherjee, Richard Fletcher, Martin W Zwierlein We report on the realization of a geometrically squeezed state of a rapidly rotating atomic Fermi gas and the measurement of its Hall response. Geometric squeezing relies on the non-commutativity of orbit center coordinates in a rotating frame - analogous to magnetron motion of ions in a magnetic field. A rotating, elliptical harmonic trap realizes the squeezing Hamiltonian for guiding center motion. The Fermi gas thus shrinks down in one direction to a size limited, via Pauli exclusion, to the width of the highest occupied cyclotron mode. In the orthogonal direction it expands exponentially, at a local speed given by the local Hall drift velocity, analogous to the E x B drift of charged particles in crossed electric and magnetic fields. Our work paves the way towards studying quantum Hall physics with atomic Fermi gases. |
Friday, June 4, 2021 10:54AM - 11:06AM Live |
Z06.00003: Controlling Transport of Bose-Einstein Condensates with a Tunable Synthetic Magnetic Flux Shih-Wen Feng, Chuan-Hsun Li, Yangqian Yan, Sayan Choudhury, David Blasing, Qi Zhou, Yong Chen Manipulating quantum systems with external fields is fundamentally important for quantum science and technology. For example, giant magnetoresistance, where the electronic transport is tunable by an external magnetic field, has rich applications such as memory devices. Highly controllable atomic systems offer opportunities to observe phenomena inaccessible in conventional platforms, such as exploring physics inherent in spaces beyond planar geometries . Here, we realize a Bose-Einstein condensate (BEC) on a synthetic topological Hall cylinder subject to net radial and axial synthetic magnetic fluxes. We observe the emergence of symmetry-protected topological band crossings absent in planar spaces. Breaking the symmetry induces a topological transition manifested as gap opening at band crossings and further allows for controlling BEC's transport with a tunable synthetic axial magnetic flux. We calibrate this axial flux by performing quench experiments and employ it to control spin compositions of the BEC during transport, reminiscent of a "magnetotransport" behavior. Our work provides insights into utilizing unconventional spaces to realize novel atomtronic devices. |
Friday, June 4, 2021 11:06AM - 11:18AM Live |
Z06.00004: Domain formation and dynamics in a Bose-Einstein condensate with density-dependent gauge field Kai-Xuan Yao, Zhendong Zhang, Shu Nagata, Cheng Chin We investigate the equilibrium and dynamical properties of a Bose-Einstein condensate with a density-dependent gauge field. Based on Floquet engineering, we create a gauge field taking on one of two values, depending on whether the density exceeds a critical threshold. This allows a large change of the gauge field over a small range of the density, as well as formation of domains where atoms condense to different momenta. Our Floquet engineering scheme results in a low rate of loss and heating, enabling us to investigate the equilibrium and dynamical properties of the many-body system over hundreds of milliseconds. We observe the dependence of the condensate momentum on the local density in equilibrium, and find good agreement with theoretical predictions. We further study the dynamics of the domain walls in response to a change of the gauge field, and find a behavior consistent with energy relaxation. |
Friday, June 4, 2021 11:18AM - 11:30AM Live |
Z06.00005: Observation of Zitterbewegung in Non-Abelian Gauge Field Mehedi Hasan, Chetan Madasu, Chang Chi Kwong, ketan rathod, Christian Miniatura, Frédéric Chevy, david wilkowski We experimentally observe Zitterbewegung in a two-dimensional degenerate Fermi gas, in the presence of a synthetic non-Abelian gauge field. We reveal the anisotropic nature of Zitterbewegung, namely, the direction-dependence of the oscillation-amplitude and the frequency of oscillation. To observe these effects, we leverage the momentum-dependence of the energy eigenstates, by introducing a kick to the atomic wave packet. Complete suppression of the Zitterbewegung is observed at special angles in momentum-space, and this phenomenon is understood with the spin-texture of this spin-orbit coupled system. The role of Fermi degeneracy is manifested in the damping of the oscillation. |
Friday, June 4, 2021 11:30AM - 11:42AM Live |
Z06.00006: Realization of a chiral BF theory in an optically dressed Bose-Einstein condensate Ramon Ramos, Anika Frölian, Craig Chisholm, Elettra Neri, Cesar Cabrera, Alessio Celi, Leticia Tarruell Ultracold atoms constitute a versatile testbed for exploring the behaviour of quantum matter subjected to electric and magnetic fields. Whereas, most experiments consider classical gauge fields that act as a simple static background for the atoms, gauge fields appearing in nature are instead quantum dynamical entities that are influenced by the spatial configuration and motion of matter, and that fulfill local symmetry constrains. In this talk, we will discuss the realization of a chiral BF theory in an optically-dressed Bose-Einstein condensate. This gauge theory, initially proposed as a model for linear anyons [1,2], is a one-dimensional reduction of the Chern-Simons theory normally used to describe fractional quantum Hall systems. By using the local symmetry constraint, we encode the gauge field in terms of the matter. The result is a system with chiral interactions, which we engineer by synthesizing optically dressed atomic states with a momentum-dependent scattering length. When this dependence is linear, matter behaves as if minimally coupled to a density-dependent vector potential. We experimentally observe its two main features: the formation of chiral bright solitons - self-bound states of the matter field that only exist when propagating in one direction – and the back-action of matter into the gauge field. |
Friday, June 4, 2021 11:42AM - 11:54AM Live |
Z06.00007: Measuring individual gap closings in a Floquet-Creutz ladder Kilian Sandholzer, Joaquín Minguzzi, Anne-Sophie Walter, Zijie Zhu, Konrad G Viebahn, Tilman Esslinger Ultracold atoms in optical lattices serve as a formidable platform to study the physics of interacting quantum particles in lattices. The interplay between strong interactions and the geometry, dimensionality and topology of the bandstructure promises the exploration of phenomena ranging from frustrated magnetism to fractional Chern insulators. In particular, Floquet band engineering has been used to create topological band structures. |
Friday, June 4, 2021 11:54AM - 12:06PM Live |
Z06.00008: Bosonic Pfaffian State in the Hofstadter-Bose-Hubbard Model Felix A Palm, Maximilian Buser, Julian Leonard, Monika Aidelsburger, Ulrich J Schollwoeck, Fabian Grusdt Topological states of matter, such as fractional quantum Hall states, are an active field of research due to their exotic excitations. In particular, ultracold atoms in optical lattices provide a highly controllable and adaptable platform to study such new types of quantum matter. However, finding a clear route to realize non-Abelian quantum Hall states in these systems remains challenging. Here we use the density-matrix renormalization-group (DMRG) method to study the Hofstadter-Bose-Hubbard model at filling factor ν=1 and find strong indications that at α=1/6 magnetic flux quanta per plaquette the ground state is a lattice analog of the continuum non-Abelian Pfaffian. We study the on-site correlations of the ground state, which indicate its paired nature at ν=1, and find an incompressible state characterized by a charge gap in the bulk. We argue that the emergence of a charge density wave on thin cylinders and the behavior of the two- and three-particle correlation functions at short distances provide evidence for the state being closely related to the continuum Pfaffian. The signatures discussed here are accessible in current cold atom experiments and we show that the Pfaffian-like state is readily realizable in few-body systems using adiabatic preparation schemes. |
Friday, June 4, 2021 12:06PM - 12:18PM Live |
Z06.00009: Probing quantum phases and the Hall response in bosonic flux ladders Maximilian Buser, Sebastian Greschner, Claudius Hubig, Leticia Tarruell, Fabian Heidrich-Meisner, Thierry Giamarchi, Ulrich J Schollwoeck The focus of this talk is on bosonic flux ladders. First, we touch on a model which is envisioned to be realized in a future quantum gas experiment exploiting the internal states of potassium atoms as a synthetic dimension. Considering specifics of the future experiment, we map out the ground-state phase diagram and report on Meissner and biased-ladder phases. We show that quantum quenches of suitably chosen initial states can be used to probe the equilibrium properties of the dominant ground-state phases. |
Friday, June 4, 2021 12:18PM - 12:30PM Live |
Z06.00010: Lattice Dynamics and Galilean Symmetry in a Zeeman Lattice Md Kamrul Hoque Ome, H. He, Ethan Crowell, Sean Mossman, Thomas M Bersano, Y. Zhang, Peter W Engels Spin-orbit coupling and optical lattices are two powerful yet distinct cornerstones of modern quantum gas experiments. While optical lattices break translation symmetry, spin-orbit coupling in the plane-wave regime does not directly lead to a periodic lattice structure and breaks Galilean invariance. Here we demonstrate that starting with a spin-orbit coupled BEC and adding an additional radio-frequency field can lead to an emergent lattice structure even though neither of the two ingredients are periodic in space. We discuss the band structure of such a Zeeman lattice and show that Galilean symmetry can be restored. In our experiments, we demonstrate that Bloch oscillations can be driven in the Zeman lattice and also discuss the application of other experimental techniques such as lattice shaking for band spectroscopy. This line of research opens the door to an exploration of spin-selectivity and flat-band properties exploiting Zeeman lattices. |
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