We investigate the behaviour of a two-component Fermi superfluid in a double-well potential. We numerically solve the time dependent Bogoliubov-de Gennes equations and characterize the regimes of Josephson oscillations and self-trapping for different potential barriers and initial conditions. In the weak link limit the results agree with a two-mode model where the relative population and the phase difference between the two wells obey coupled nonlinear Josephson equations. A more complex dynamics is predicted for large amplitude oscillations and large tunneling.
In this work, a Josephson relation is generalized to a multi-component fermion superfluid. Superfluid density is expressed through a two-particle Green function for pairing channels. When the system has only one gapless collective excitation mode, the Josephson relation is simplified, which is given in terms of the order parameters and the trace of two-particle Green functions. In the presence of inversion symmetry, the superfluid density is directly related to the inverse of pairing fluctuation matrix. The results of the superfluid density in Haldane model show that the generalized Josephson …
Vortex dynamics in rotating dipolar supersolids across Josephson and self-trapping regimes
University of the Basque Country UPV/EHU（巴斯克大学）；IKERBASQUE, Basque Foundation for Science（伊卡巴斯基奎巴斯克科学基金会）；Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales（布宜诺斯艾利斯大学理学院）；CONICET - Universidad de Buenos Aires, Instituto de Física de Buenos Aires (IFIBA)（阿根廷国家科学研究委员会-布宜诺斯艾利斯大学布宜诺斯艾利斯物理研究所）
Rotation Sensing via Josephson-frequency Splitting in a Toroidal Superfluid
Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche (INO-CNR)（意大利国家光学研究所，意大利国家研究委员会）；European Laboratory for Nonlinear Spectroscopy (LENS)（欧洲非线性光谱学实验室）
Self-sustained Josephson dynamics and self-trapping in supersolids
University of the Basque Country UPV/EHU（巴斯克地区大学）；IKERBASQUE, Basque Foundation for Science（伊卡巴斯科，巴斯克科学基金会）；Universidad de Buenos Aires（布宜诺斯艾利斯大学）；CONICET - Universidad de Buenos Aires, Instituto de Física de Buenos Aires (IFIBA)（阿根廷国家科学研究委员会-布宜诺斯艾利斯大学，布宜诺斯艾利斯物理研究所）
Macroscopic quantum self-trapping in bosonic Josephson junctions: an exact quantum treatment
Università di Padova（帕多瓦大学）；Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova（意大利国家核物理研究所（INFN）帕多瓦分部）；Université Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；CNRS（法国国家科学研究中心）；Istituto Nazionale di Ottica (INO) del Consiglio Nazionale delle Ricerche (CNR)（意大利国家研究委员会光学研究所（INO））
The dc Josephson effect provides a powerful phase-sensitive tool for investigating superfluid order parameters. We report on the observation of dc Josephson supercurrents in strongly interacting fermionic superfluids across a tunnelling barrier in the absence of any applied potential difference. For sufficiently strong barriers, we observe a sinusoidal current-phase relation, in agreement with Josephson's seminal prediction. We map out the zero-resistance state and its breakdown as a function of junction parameters, extracting the Josephson critical current behaviour. By comparing our results …
Sub-unity superfluid fraction of a supersolid from self-induced Josephson effect
Università degli studi di Firenze（佛罗伦萨大学）；CNR-INO（意大利国家研究委员会光学研究所）；European Laboratory for Nonlinear Spectroscopy（欧洲非线性光谱学实验室）；QSTAR（量子与统计热力学研究前沿中心）；Università degli studi di Napoli “Federico II”（那不勒斯费德里科二世大学）
We investigate the macroscopic quantum tunneling of fermionic superfluids in the two-dimensional BCS-BEC crossover by using an effective tunneling energy which explicitly depends on the condensate fraction and the chemical potential of the system. We compare the mean-field effective tunneling energy with the beyond-mean-field one finding that the mean-field tunneling energy is not reliable in the BEC regime of the crossover. Then we solve the Josephson equations of the population imbalance and the relative phase calculating the frequency of tunneling oscillation both in the linear regime and i…
Josephson junctions are essential ingredients in the superconducting circuits used in many existing quantum technologies. Additionally, ultracold atomic quantum gases have also become essential platforms to study superfluidity. Here, we explore the analogy between superconductivity and superfluidity to present an intriguing effect caused by a thin finite barrier in a quasi-one-dimensional toroidal spinor Bose--Einstein condensate (BEC). In this system, the atomic current density flowing through the edges of the barrier oscillates, such as the electrical current through a Josephson junction in …
We provide a complete study of the phase diagram characterising the distinct dynamical regimes emerging in a three-dimensional Josephson junction in an ultracold quantum gas. Considering trapped ultracold superfluids separated into two reservoirs by a barrier of variable height and width, we analyse the population imbalance dynamics following a variable initial population mismatch. We demonstrate that as the chemical potential difference is increased, the system transitions from Josephson plasma oscillations to either a dissipative (in the limit of low and narrow barriers) or a self-trapped re…
Anyons are particles with intermediate quantum statistics whose wavefunction acquires a phase $e^{iθ}$ by particle exchange. Inspired by proposals of simulating anyons using ultracold atoms trapped in optical lattices, we study a two-site anyonic Josephson junction, i.e. anyons confined in a one-dimensional double-well potential. We show, analytically and numerically, that many properties of anyonic Josephson junctions, such as Josephson frequency, imbalanced solutions, macroscopic quantum self-trapping, coherence visibility, and condensate fraction, crucially depend on the anyonic angle $θ$. …
Trapping-potential dependence of the unitary Fermi gas at the BCS-BEC crossover
University of Washington（华盛顿大学）；Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern（伯尔尼大学阿尔伯特·爱因斯坦基础物理中心理论物理研究所）；INFN sezione di Torino（都灵 INFN 分部）
Bose-Einstein condensates loaded in one-dimensional bichromatic optical lattices with constituent sublattices having incommensurate periods is considered. Using the rational approximations for the incommensurate periods, we show that below the mobility edge the localized states are distributed nearly homogeneously in the space and explore the versatility of such potentials. We show that superposition of symmetric and anti-symmetric localized can be used to simulate various physical dynamical regimes, known to occur in double-well and multi-well traps. As examples, we obtain an alternative real…
