Bragg spectroscopy is used to measure excitations of a trapped, quantum-degenerate gas of 87Rb atoms in a 3-dimensional optical lattice. The measurements are carried out over a range of optical lattice depths in the superfluid phase of the Bose-Hubbard model. For fixed wavevector, the resonant frequency of the excitation is found to decrease with increasing lattice depth. A numerical calculation of the resonant frequencies based on Bogoliubov theory shows a less steep rate of decrease than the measurements.
Nonlinear polaron-like dynamics of the two-dimensional Wigner solid (WS) on superfluid $^{4}\mathrm{He}$ are theoretically analyzed in different models and transport regimes for their similarities and distinctions. The Bragg-Cherenkov (BC) resonant excitation of surface waves and WS decoupling from surface dimples were usually considered in terms of a dc transport model. At the same time, field-velocity characteristics of the WS are measured under ac conditions and presented for time-averaged quantities. Here the nonlinear equation of motion of the WS coupled to surface dimples is studied for …
With use of the U(1) quantum rotor method in the path integral effective action formulation, we have confirmed the mathematical similarity of the phase Hamiltonian and of the extended Bose-Hubbard model with density-induced tunneling (DIT). Moreover, we have shown that the latter model can be mapped to a pseudospin Hamiltonian that exhibits two coexisting (single-particle and pair) superfluid phases. Phase separation of the two has also been confirmed, determining that there exists a range of coefficients in which only pair condensation, and not single-particle superfluidity, is present. The D…
We use unbiased computational methods to elucidate the onset and properties of pair superfluidity in two-species fermionic and bosonic systems with onsite interspecies attraction loaded in one-dimensional optical lattice. We compare results from quantum Monte Carlo (QMC) and density matrix renormalization group (DMRG), emphasizing the one-to-one correspondence between the Drude weight tensor, calculated with DMRG, and the various winding numbers extracted from the QMC. Our results show that, for any nonvanishing attractive interaction, pairs form and are the sole contributors to superfluidity,…
Checkerboard Bose Hubbard Ladders using Transmon Arrays
Cornell University（康奈尔大学）；Google Quantum AI（谷歌量子人工智能）；Kavli Institute for Theoretical Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校卡弗里理论物理研究所）
