Quantum Walk Search with Time-Reversal Symmetry Breaking

Hamiltonians of Bipartite Walks

In this paper, we introduce a discrete quantum walk model called bipartite walks. Bipartite walks include many known discrete quantum walk models, like arc-reversal walks, vertex-face walks. For the transition matrix of a quantum walk, there is a Hamiltonian associated with it. We will study the Hamiltonians of the bipartite walks. Let $S$ be a skew-symmetric matrix. We are mainly interested in the Hamiltonians of the form $iS$. We show that the Hamiltonian can be written as $iS$ if and only if the adjacency matrix of the bipartite graph is invertible. We show that arc-reversal walks and verte…

Superfluid-Mott transitions and vortices in the Jaynes-Cummings-Hubbard lattices with time reversal symmetry breaking

We investigate the groundstate behaviour of Jaynes-Cummings-Hubbard lattices in the presence of a synthetic magnetic field, via a Gutzwiller ansatz. Specifically, we study the Mott-Superfluid transition, and the formation of vortex lattices in the superfluid regime. We find a suppression of the superfluid fraction due to the frustration induced by the incommensurate magnetic and spacial lattice lengths. We also predict the formation of regime.

Enhancement in Breaking of Time-reversal Invariance in the Quantum Kicked Rotor

We study the breaking of time-reversal invariance (TRI) by the application of a magnetic field in the quantum kicked rotor (QKR), using Izrailev's finite-dimensional model. There is a continuous crossover from TRI to time-reversal non-invariance (TRNI) in the spectral and eigenvector fluctuations of the QKR. We show that the properties of this TRI $\rightarrow$ TRNI transition depend on $α^2/N$, where $α$ is the chaos parameter of the QKR and $N$ is the dimensionality of the evolution operator matrix. For $α^2/N \gtrsim N$, the transition coincides with that in random matrix theory. For $α^2/N…

Gauge fields emerging from time reversal symmetry breaking for spin-5/2 fermions in a honeycomb lattice

We propose an experimentally feasible setup with ultracold alkaline earth atoms to simulate the dynamics of U(1) lattice gauge theories in 2+1 dimensions with a Chern-Simons term. To this end we consider the ground state properties of spin-5/2 alkaline earth fermions in a honeycomb lattice. We use the Gutzwiller projected variational approach in the strongly repulsive regime in the case of filling 1/6. The ground state of the system is a chiral spin liquid state with $2π/3$ flux per plaquette, which spontaneously violates time reversal invariance. We demonstrate that due to the breaking of tim…

手性原子系统中时间反演对称性的自发对称破缺与时间晶体态

Spontaneous Symmetry Breaking of Time-Reversal-Symmetry and Time-Crystal States in Chiral Atomic Systems

研究简并基态原子与互易环境在无偏置下的相互作用，发现电子自旋磁矩与手性偶极跃迁可导致时间反演对称性自发破缺或类时间晶体态，为纳米尺度非互易响应提供新机制。

格点费米子模拟在螺旋Luttinger液体中自发生时间反演对称性破缺

Lattice fermion simulation of spontaneous time-reversal symmetry breaking in a helical Luttinger liquid

该研究扩展了最近发展的

在时间反演对称破坏下的鲁棒相关性诱导定位

Robust Correlation-Induced Localization Under Time-Reversal Symmetry Breaking

研究一维无序系统中长程相关 hopping 的安德森局域化，发现时间反演对称破坏参数有限时的鲁棒相关性诱导局域化，且通过波包扩散研究动态相图。

Tunneling-Induced Restoration of the Degeneracy and the Time-Reversal Symmetry Breaking in Optical Lattices

We study the ground-state properties of bosons loaded into the $p$-band of a one dimensional optical lattice. We show that the phase diagram of the system is substantially affected by the anharmonicity of the lattice potential. In particular, for a certain range of tunneling strength, the full many-body ground state of the system becomes degenerate. In this region, an additional symmetry of the system, namely the parity of the occupation number of the chosen orbital, is spontaneously broken. The state with nonvanishing staggered angular momentum, which breaks the time-reversal symmetry, become…

Optimal energy conversion through anti-adiabatic driving breaking time-reversal symmetry

Starting with Carnot engine, the ideal efficiency of a heat engine has been associated with quasi-static transformations and vanishingly small output power. Here, we exactly calculate the thermodynamic properties of a isothermal heat engine, in which the working medium is a periodically driven underdamped harmonic oscillator, focusing instead on the opposite, anti-adiabatic limit, where the period of a cycle is the fastest time scale in the problem. We show that in that limit it is possible to approach the ideal energy conversion efficiency $η=1$, with finite output power and vanishingly small…

Time-reversal symmetry breaking superconducting ground state in the doped Mott insulator on the honeycomb lattice

The emergence of superconductivity in doped Mott insulators has been debated for decades. In this paper, we report the theoretical discovery of a time-reversal symmetry breaking superconducting ground state in the doped Mott insulator (described by the well known t-J model) on honeycomb lattice, based on a recently developed variational method: the Grassmann tensor product state approach. As a benchmark, we use exact diagonalization and density-matrix renormalization methods to check our results on small clusters. We find systematic consistency for the ground-state energy as well as other phys…

Current reversals in a rocking ratchet: the frequency domain

Motivated by recent work [D. Cubero et al., Phys. Rev. E 82, 041116 (2010)], we examine the mechanisms which determine current reversals in rocking ratchets as observed by varying the frequency of the drive. We found that a class of these current reversals in the frequency domain are precisely determined by dissipation-induced symmetry breaking. Our experimental and theoretical work thus extends and generalizes the previously identified relationship between dynamical and symmetry-breaking mechanisms in the generation of current reversals.