Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session T2: Focus Session: New Topological Quantum MatterFocus
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Chair: Waseem Bakr, Princeton University Room: 306-307 |
Friday, June 9, 2017 8:00AM - 8:30AM |
T2.00001: Observation of a dynamical topological phase transition in the non-equilibrium dynamics of ultracold quantum gases in driven optical lattices Invited Speaker: Christof Weitenberg Ultracold atoms are a versatile system to emulate solid-state physics including the fascinating phenomena of gauge fields and topological band structures. By circular driving of a hexagonal optical lattice, we engineer the Berry curvature of the Bloch bands and realize a Haldane-like model. We have developed a full momentum-resolved state tomography of the Bloch states, which allows measuring the distribution of Berry curvature and obtaining the Chern number [1]. Furthermore, we study the time-evolution of the many-body wavefunction after a sudden quench of the lattice parameters and observe the appearance, movement, and annihilation of dynamical vortices in reciprocal space. We identify them as the Fisher zeros in the Loschmidt amplitude and define them as a dynamical equivalent of an order parameter, which suddenly changes its value at critical evolution times [2]. Our measurements constitute the first observation of a so-called dynamical phase transition and address the intriguing question of the relation between this phenomenon and the equilibrium phase transition in the system. [1] Flaeschner et al., Science 352, 1091 (2016). [2] Flaeschner et al., arXiv:1608.05616 (2016). [Preview Abstract] |
Friday, June 9, 2017 8:30AM - 9:00AM |
T2.00002: Crystalline symmetry in topological quantum states of ultracold atoms Invited Speaker: Qi Zhou Symmetry plays a fundamental role in topological quantum states. In this talk, I will discuss practical schemes for exploring the interplay between crystalline symmetries and topology in ultracold atoms. In optical lattices with nonsymmorphic symmetries, nonsymmorphic Chern insulators arise. A variety of new phenomena, such as band structures resembling Mobius strips, quantum dynamics controlled by non-abelian Berry connections, and nonsymmorphic topological pumping, can be naturally accessed in laboratories. [Preview Abstract] |
Friday, June 9, 2017 9:00AM - 9:12AM |
T2.00003: Disordered topological wires in a momentum-space lattice Eric Meier, Fangzhao An, Bryce Gadway One of the most interesting aspects of topological systems is the presence of boundary modes which remain robust in the presence of weak disorder. We explore this feature in the context of one-dimensional (1D) topological wires where staggered tunneling strengths lead to the creation of a mid-gap state in the lattice band structure. Using Bose-condensed $^{87}$Rb atoms in a 1D momentum-space lattice, we probe the robust topological character of this model when subjected to both site energy and tunneling disorder. We observe a transition to a topologically trivial phase when tailored disorder is applied, which we detect through both charge-pumping and Hamiltonian-quenching protocols. In addition, we report on efforts to probe the influence of interactions in topological momentum-space lattices. [Preview Abstract] |
Friday, June 9, 2017 9:12AM - 9:24AM |
T2.00004: Chern number measurement in photonic Landau levels Nathan Schine, Michelle Chalupnik, Jonathan Simon Nontrivial topology is at the heart of a host of intriguing phenomena in condensed matter physics. Synthetic materials consisting of a quantum gas of photons or ultracold atoms have established themselves as ideal systems to explore these phenomena. As experiments push into the strongly-interacting, strongly-correlated regime, characterizing topological many-body states through measurements of topological quantum numbers becomes critical. We present a real-space Chern number measurement in a photonic integer quantum Hall system, produced in a degenerate manifold of a multimode non-planar ring resonator. Through controlled spatial excitation of the resonator and holographic reconstruction of the resulting modes, we measure arbitrary `band projectors' from which the Chern number is calculated. This system and measurement technique is compatible with strong interactions via cavity Rydberg electromagnetically induced transparency. We will further discuss how spatial curvature in our system allows measurement of two additional topological quantum numbers, enabling detailed characterization of novel manybody quantum states. [Preview Abstract] |
Friday, June 9, 2017 9:24AM - 9:36AM |
T2.00005: Topological states of photons in coupled microwave cavities John Owens, Aman LaChapelle, Ruichao Ma, Brendan Saxberg, Jonathan Simon, David Schuster We present recent results in using coupled cavity arrays to explore quantum many-body phenomena. We create tight binding lattices with arrays of evanescently coupled three-dimensional coaxial microwave cavities. Topologically non-trivial band structures are engineered by utilizing the chiral coupling of the cavity modes to ferrite spheres in a magnetic field. Using screws made of different dielectric material, we can control every lattice site frequency, loss, and coupling strength to its neighbors. We then can probe each lattice site and measure the band structure, the edge dispersion, and time-resolved dynamics of pulses we inject at a particular site. These lattices can be cooled to superconducting temperatures to realize low disorder, long-coherence, topological tight binding models that are compatible with effective onsite photon-photon interactions by coupling lattice sites to superconducting qubits. This will allow us to explore the interplay between topology and coherent interaction in these artificial strongly-correlated photonic quantum materials. [Preview Abstract] |
Friday, June 9, 2017 9:36AM - 9:48AM |
T2.00006: Detection of topological invariants in driven-dissipative and interacting systems Dominik Linzner, Rui Li, Michael Fleischhauer We propose a conceptual detection scheme of topological invariants for thermal and driven, dissipative gaussian systems. In closed systems topological order can be measured by means of quantized transport which coincides with a quantized winding of the polarization. This connection breaks down for mixed states, e.g. in the presence of a finite temperature. While in previous work [1] we have identified that the winding of the polarization is still quantized in open systems and can therefore be used to classify topological order, the same no longer holds true for transport properties. We show for the case of one-dimensional systems that an auxiliary system at $T\approx 0$ coupled to the finite-temperature or driven system can inherit its topological properties. Thus a non-trivial winding of the polarization in the open system leads to a quantized particle transport in the auxiliary system. We also show for the example of the 1D extended superlattice Bose-Hubbard model that the transfer of topological properties also holds for interacting systems. This allows us to detect topological order in driven-dissipative as well as interacting systems. [1] D. Linzner, L. Wawer, F. Grusdt and M. Fleischhauer, Phys. Rev. B 94, 201105(R) (2016) [Preview Abstract] |
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