Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session F39: Invited Session: Cold Atomic Gases with Synthetic Spin-Orbit Coupling |
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Sponsoring Units: DCMP DAMOP Room: Mile High Ballroom 2A-3A |
Tuesday, March 4, 2014 8:00AM - 8:36AM |
F39.00001: Spin-orbit coupled bosons in optical lattices Invited Speaker: William Cole The interplay between strong correlations and spin-orbit coupling has recently become a significant theme in condensed matter physics. In light of this, we review the proposed realization of a spin-orbit coupled Hubbard model using cold atoms in a synthetic gauge field and an optical lattice potential. Focusing our attention on two component bosons, a variety of theoretical techniques are used to identify broken symmetry states, such as magnetically textured superfluids and Mott insulators. We discuss the spin Hall effect and anomalous Hall effect (in the presence of spontaneous time reversal symmetry breaking). Spin-orbit coupling also leads to interesting plaquette current patterns, and we describe the possibility for experimental confirmation of these using a quench of the lattice potential. Reference: Phys. Rev. Lett. 109, 085302 (2012) [Preview Abstract] |
Tuesday, March 4, 2014 8:36AM - 9:12AM |
F39.00002: The spin Hall effect in a quantum gas Invited Speaker: Ian Spielman |
Tuesday, March 4, 2014 9:12AM - 9:48AM |
F39.00003: Many-body physics of spin-orbit-coupled quantum gases Invited Speaker: Victor Galitski Spin-orbit-coupled systems provides a unique area in which a fascinating variety of novel and fundamental phenomena occur. Recent theoretical and experimental works have demonstrated that dressed states of ultra-cold atoms coupled to light acquire effective spin-orbit (SO) interactions. In this talk, I will review recent progress in theoretical understanding of these synthetic spin-orbit coupled quantum systems. First, I will discuss possible single-particle Hamiltonians for dressed states that arise in various laser schemes, including Rashba and Dresselhaus-type Hamiltonians, three-dimensional isotropic SO (Weyl) interaction, and su(3) SO coupling. Then, I will discuss many-body quantum physics that arise in bosonic systems. Possible ground states of SO-coupled Bose-Einstein condensates will be discussed. It will be shown that when put on a lattice, SO-coupled, interacting bosons give rise to Mott insulators with exotic spin orders, such as a skyrmion lattice phase and various stripe orders. Finally, I will discuss non-equilibrium phenomena in SO-coupled systems and show how the interplay between spin-orbit coupling and interactions results in interesting quantum dynamical systems, which feature a rich variety of time-dependent behaviors and dynamical transitions. [Preview Abstract] |
Tuesday, March 4, 2014 9:48AM - 10:24AM |
F39.00004: Spin-Orbit Coupled Quantum Gases: New Physics and Challenges Invited Speaker: Hui Zhai In this talk I will review recent progresses in studying spin-orbit coupling in ultracold quantum gases. I will discuss several examples of new states or phenomena when spin-orbit coupling is introduced to ultracold atomic gases. i) the single particle ground state degeneracy will lead to condensate with stripe order for bosons and interesting finite temperature phase diagram; ii) the new feature in two-body physics strongly modifies the scenario of fermion pairing; On the other hand, I will also discuss great challenges in this direction that is the heating problem. I will present several ways to overcome the difficult, for instance, by utilizing highly magnetic lanthanide atoms. [Preview Abstract] |
Tuesday, March 4, 2014 10:24AM - 11:00AM |
F39.00005: Spin-Orbit Coupled Fermi Gases and Solitons in Fermionic Superfluids Invited Speaker: Lawrence Cheuk The coupling of the spin of electrons to their motional state lies at the heart of topological phases of matter. We have created and detected spin-orbit coupling in an atomic Fermi gas via spin-injection spectroscopy, which characterizes the energy-momentum dispersion and spin composition of the quantum states. For energies within the spin-orbit gap, the system acts as a spin diode. To fully inhibit transport, we open an additional spin gap with radio-frequency coupling, thereby creating a spin-orbit coupled lattice whose spinful band structure we probe. In the presence of s-wave interactions, spin-orbit coupled fermion systems should display induced p-wave pairing and consequently topological superfluidity. Such systems can be described by a relativistic Dirac theory with a mass term that can be made to vary spatially. Topologically protected edge states are expected to occur whenever the mass term changes sign. A system that similarly supports edges states is the strongly interacting atomic Fermi gas near a Feshbach resonance. Topological excitations, such as vortices - line defects - or solitons - planar defects - have been described theoretically for decades in many different physical contexts. In superconductivity and superfluidity they represent a defect in the order parameter and give rise to localized bound states. We have created and directly observed solitons in a fermionic superfluid. These are found to be stable for many seconds, allowing us to track their oscillatory motion in the trapped superfluid. Their trapping period increases dramatically as the interactions are tuned from the BEC to the BCS regime. At the Feshbach resonance, their period is an order of magnitude larger than expected from mean-field Bogoliubov-de Gennes theory, signaling strong effects of quantum fluctuations and possible filling of Andreev bound states. Our work paves the way towards the experimental study and control of fermionic edge states in ultracold gases. [Preview Abstract] |
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