Jul 2018
Jul 1 - Jul 2 Biao Huang, Jul 3- Jul 7 Xuguang Yue, Jul 8- Jul 12 Haiyuan Zou, Jul 13- Jul 17 Zehan Li, Jul 18- Jul 22 Jiansong Pan, Jul 23-Jul 27 Ahmet Keles, Jul 28- Jul 31 Max Aarzamazovs
Jul 12 arXiv:1807.03838 [pdf, ps, other] Static properties of two connected Bose-Hubbard rings Albert Escrivà, Bruno Juliá-Díaz, Montserrat Guilleumas Subjects: Quantum Gases (cond-mat.quant-gas) We consider two coupled Bose-Hubbard rings populated with ultra-cold bosons with repulsive interactions. The atoms can either tunnel between the sites of the same ring, with a given inter-ring coupling, or between the sites of different rings coupled by an intra-ring coupling. By solving the corresponding Bose-Hubbard Hamiltonian we obtain the many-body ground state for different values of the interaction and tunneling strengths. We characterize the static many-body properties of the ground state by means of coherence, correlations and entanglement. Jul 11 arXiv:1807.03572 [pdf, other] Heat distribution of a quantum harmonic oscillator Tobias Denzler, Eric Lutz Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech) We consider a thermal quantum harmonic oscillator weakly coupled to a heat bath at a different temperature. We analytically study the quantum heat exchange statistics between the two systems using the quantum-optical master equation. We exactly compute the characteristic function of the heat distribution and show that it verifies the Jarzynski-W\'ojcik fluctuation theorem. We further evaluate the heat probability density in the limit of long thermalization times, both in the low and high temperature regimes, and investigate its time evolution by calculating its first two cumulants. Jul 10 arXiv:1807.02577 [pdf, other] Light-induced coherence in an atom-cavity system Christoph Georges, Jayson G. Cosme, Ludwig Mathey, Andreas Hemmerich Comments: 5 page, 3 figures Subjects: Quantum Gases (cond-mat.quant-gas) We demonstrate light-induced formation of coherence in a cold atomic gas system that utilizes the suppression of a competing density wave (DW) order. The condensed atoms are placed in an optical cavity and pumped by an external optical standing wave, which induces a long-range interaction, mediated by photon scattering, and DW order above a critical pump strength. We show that light induced modulation of the pump wave can suppress this DW order and restore coherence. This establishes a foundational principle of dynamical control of competing orders analogous to a hypothesized mechanism for light induced superconductivity in high-$T_c$ cuprates. Jul 9 arXiv:1807.02146 [pdf, other] Absence of Criticality in the Phase Transitions of Open Floquet Systems Steven Mathey, Sebastian Diehl Subjects: Statistical Mechanics (cond-mat.stat-mech); Quantum Gases (cond-mat.quant-gas); High Energy Physics - Theory (hep-th) Floquet systems hold the promise to realize novel phases of matter without equilibrium counterpart. The coupling to a bath can stabilize a stationary state at finite energy density. We address here the nature of phase transitions in such systems at rapid drive, complementary to the Kibble-Zurek scenario at slow drive. While the infinitely rapidly driven limit exhibits a second order phase transition, here we reveal a universal mechanism showing that fluctuations associated to the first rotating wave correction drive the transition first order at any finite driving. The effect is rooted in the degeneracy of critical poles in weakly coupled higher Floquet-Brillouin zones, in some analogy to the Coleman-Weinberg or Halperin-Lubensky-Ma phenomenon. The critical exponents of the infinitely rapidly driven fixed point -- including a new, independent one -- can be probed experimentally upon smoothly tuning towards that limit.
