We perform an analysis of the supercooled state in an analogue to an early universe phase transition based on a one dimensional, two-component Bose gas. We demonstrate that the thermal fluctuations in the relative phase between the components are characteristic of a relativistic thermal system. Furthermore, we demonstrate the equivalence of two different approaches to the decay of the metastable state: specifically a non-perturbative thermal instanton calculation and a stochastic Gross--Pitaevskii simulation.
We perform an analysis of the supercooled state in an analogue of an early universe phase transition based on a one dimensional, two-component Bose gas with time-dependent interactions. We demonstrate that the system behaves in the same way as a thermal, relativistic Bose gas undergoing a first order phase transition. We propose a way to prepare the state of the system in the metastable phase as an analogue to supercooling in the early universe. While we show that parametric resonances in the system can be suppressed by thermal damping, we find that the theoretically estimated thermal damping …
We propose to test the concept of seeded vacuum decay in cosmology using an analogue gravity Bose-Einstein condensate system. The role of the nucleation seed is played by a vortex within the condensate. We present two complementary theoretical analyses that demonstrate seeded decay is the dominant decay mechanism of the false vacuum. First, we adapt the standard instanton methods to the Gross-Pitaevskii equation. Second, we use the truncated Wigner method to study vacuum decay.
For over twenty years, ultra-cold atomic systems have formed an almost perfect arena for simulating different quantum many-body phenomena and exposing their non-obvious and very often counterintuitive features. Thanks to extremely precise controllability of different parameters they are able to capture different quantum properties which were previously recognized only as theoretical curiosities. Here, we go over the current experimental progress in exploring the curious one-dimensional quantum world of fermions from the perspective of three subjectively selected trends being currently under vi…
We propose an analog quantum simulator for simulating real time dynamics of $(1+1)$-d non-Abelian gauge theory well within the existing capacity of ultracold atom experiments. The scheme calls for the realization of a two-state ultracold fermionic system in a 1-dimensional bipartite lattice, and the observation of subsequent tunneling dynamics. Being based on novel loop string hadron formalism of SU(2) lattice gauge theory, this simulation technique is completely SU(2) invariant and simulates accurate dynamics of physical phenomena such as string breaking and/or pair production. The scheme is …
Towards $2+1$D quantum electrodynamics on a cold-atom quantum simulator
Università di Padova（帕多瓦大学）；Padua Quantum Technologies Research Center, Università degli Studi di Padova（帕多瓦量子技术研究中心，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）；Max Planck Institute of Quantum Optics（马克斯·普朗克量子光学研究所）；Ludwig Maximilian University of Munich（慕尼黑路德维希-马克西米利安大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；University of Trento（特伦托大学）；INFN-TIFPA, Trento Institute for Fundamental Physics and Applications（INFN-TIFPA，特伦托基础物理与应用研究所）；Southern University of Science and Technology（南方科技大学）
We study a transition between a homogeneous and an inhomogeneous phase in a system of one-dimensional, Raman tunnel-coupled Bose gases. The homogeneous phase shows a flat density and phase profile, whereas the inhomogeneous ground state is characterized by periodic density ripples, and a soliton staircase in the phase difference. We show that under experimentally viable conditions the transition can be tuned by the wavevector difference $Q$ of the Raman beams and can be described by the Pokrovsky-Talapov model for the relative phase between the two condensates. Local imaging available in atom …
We propose to use ultracold fermionic atoms in one-dimensional optical lattices to quantum simulate the electronic transport in quantum cascade laser (QCL) structures. The competition between the coherent tunneling among (and within) the wells and the dissipative decay at the basis of lasing is discussed. In order to validate the proposed simulation scheme, we quantitatively address such competition in a simplified one-dimensional model. We show the existence of optimal relationships between the model parameters, maximizing the particle current, the population inversion (or their product), and…
Rotational misalignment or twisting of two mono-layers of graphene strongly influences its electronic properties. Structurally, twisting leads to large periodic supercell structures, which in turn can support intriguing strongly correlated behaviour. Here, we propose a highly tunable scheme to synthetically emulate twisted bilayer systems with ultracold atoms trapped in an optical lattice. In our scheme, neither a physical bilayer nor twist is directly realized. Instead, two synthetic layers are produced exploiting coherently-coupled internal atomic states, and a supercell structure is generat…
Quantum fields in a cold atomic simulator: relaxation and phase locking in tunnel-coupled 1D bosonic quasi-condensates
Budapest University of Technology and Economics（布达佩斯技术与经济大学）；HUN-REN-BME-BCE Quantum Technology Research Group, Institute of Physics, Budapest University of Technology and Economics（匈牙利研究网络-布达佩斯技术与经济大学-布达佩斯理工大学量子技术研究组，物理研究所）；BME-MTA Momentum Statistical Field Theory Research Group, Institute of Physics, Budapest University of Technology and Economics（布达佩斯理工大学-匈牙利科学院动量统计场论研究组，物理研究所）
Exploring topological double-Weyl semimetals with cold atoms in optical lattices
研究了光晶格中含冷原子的双Weyl半金属的拓扑性质。我们首先提出在三维光晶格中通过设计原子的跳跃来实现一个用双Weyl点模拟双Weyl半金属的紧束缚模型。证明了具有\$pm 2 $ behave as sink and source of Berry flux in momentum space connecting by two Fermi arcs and they are stabilized by the \$C_{4h}$拓扑荷的双Weyl点是点群对称的.通过引入一个可实现的\$C_4 $ breaking term, we find that each double-Weyl point splits into two single-Weyl points and obtain rich phase diagrams in the parameter space spanned by the strengths of an effective Zeeman term and the \$C_4$破缺项，该破缺项包含一个拓扑绝缘相和一个正常绝缘相，以及两个拓扑Weyl半金属相，除了双Weyl半金属相外，还包含8个和4个单Weyl点.此外，我们还通过数值模拟证明了：（i）通过测量Bloch振荡后的原子转移分数，可以检测出模拟的双Weyl点和单Weyl点;（ii）通过测量混合…
Gauge fields for ultracold atoms in optical superlattices
我们提出了一个在二维正方形光晶格中的冷原子上产生强类U（1）规范场的方案。我们的建议依赖于两个基本特征，一个长寿命的亚稳态激发态，存在于碱土金属或镱原子，和一个光学超晶格。正如Jaksch和Zoller的提议[New Journal of Physics 5，56（2003）]，相邻位点之间的激光辅助隧穿产生有效的磁场。在紧束缚近似中，原子运动由哈珀汉密尔顿描述，每个晶格元的通量实际上可以取0和$π$之间的任何值。我们展示了如何利用超晶格，以确保每个元获得相同的相位，从而模拟一个均匀的磁场。我们讨论了人工规范场对非相互作用玻色子和费米子气体的可观测结果。我们还概述了如何计划可以推广到非阿贝尔规范场。
A remarkable consequence of spontaneously breaking the time translational symmetry in a system, is the emergence of time crystals. In periodically driven systems, discrete time crystals (DTC) can be realized which have a periodicity that is n times the driving period. However, all of the experimental observations have been performed for period-doubling and period-tripling discrete time crystals. Novel physics can arise by simulating many-body physics in the time domain, which would require a genuine realisation of the n-tupling DTC. A system of ultra-cold bosonic atoms bouncing resonantly on a…
