118521941
Relativistic quantum effects of Dirac particles simulated by ultracold atoms
Quantum simulation is a powerful tool to study a variety of problems in physics, ranging from high-energy physics to condensed-matter physics. In this article, we review the recent theoretical and experimental progress in quantum simulation of Dirac equation with tunable parameters by using ultracold neutral atoms trapped in optical lattices or subject to light-induced synthetic gauge fields. The effective theories for the quasiparticles become relativistic under certain conditions in these systems, making them ideal platforms for studying the exotic relativistic effects. We focus on the realization of one, two, and three dimensional Dirac equations as well as the detection of some relativistic effects, including particularly the well-known Zitterbewegung effect and Klein tunneling. The realization of quantum anomalous Hall effects is also briefly discussed.
53385594
An intrinsic connection between topological stabilities of Fermi surfaces and topological insulators/superconductors
A topology-intrinsic connection between the stabilities of Fermi surfaces (FSs) and topological insulators/superconductors (TIs/TSCs) is revealed. In particular, a one-to-one relation between the topological types of FSs and TIs/TSCs is rigorously derived; combining it with a well-established topological theory of FSs, we produce a complete table illustrating precisely topological types of all TIs/TSCs, while a valid part of it was postulated before. Moreover, we propose and prove a general index theorem that relates the topological charge of FSs on the natural boundary of a strong TI/TSC to its bulk topological number. Implications of the general index theorem on the boundary quasi-particles are also addressed.
119293149
Particle-number fractionalization of a one-dimensional atomic Fermi gas with synthetic spin-orbit coupling
We propose an experimental scheme to simulate the fractionalization of the particle number by using a one-dimensionalspin-orbit-coupledultracoldfermionicgas.Thedesiredspin-orbitcoupling,akinklikepotential, andaconjugation-symmetry-breakingmasstermareproperlyconstructedbylaser-atominteractions,leadingtoan effectivelow-energyrelativisticDiracHamiltonianwithatopologicallynontrivialbackgroundfield.Thedesigned system supports a localized soliton excitation with a fractional particle number that is generally irrational and experimentally tunable, providing a direct realization of the celebrated generalized Su-Schrieffer-Heeger model. In addition, we elaborate on how to detect the induced soliton mode with the fractional particle number in the system.
56250567
Macroscopic Klein tunneling in spin-orbit-coupled Bose-Einstein condensates
We propose an experimental scheme to detect macroscopic Klein tunneling with spin-orbit coupled Bose-Einstein condensates (BECs). We show that a nonlinear Dirac equation with tunable parameters can be realized with such BECs. %in a simple configuration to generate the artificial spin-orbit coupling. Through numerical calculations, we demonstrate that macroscopic Klein tunneling can be clearly detected under realistic conditions. Macroscopic quantum coherence in such relativistic tunneling is clarified and a BEC with a negative energy is shown to be able to transmit transparently through a wide Gaussian potential barrier.
126306148
Quantum simulation of DIII class topological superconductors using superconducting quantum circuits
Yong Hu, Y. X. Zhao, Zheng-Yuan Xue, and Z. D. Wang Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, China and Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
55540815
Abelian and non-Abelian anyons in integer quantum anomalous Hall effect and topological phase transitions via superconducting proximity effect
We study the quantum anomalous Hall effect described by a class of two-component Haldane models on square lattices. We show that the latter can be transformed into a pseudospin triplet p + ip-wave paired superfluid. In the long wavelength limit, the ground-statewave function is described by Halperin's ( 1,1,-1) state of neutral fermions analogous to the double-layer quantum Hall effect. The vortex excitations are charge e/2 Abelian anyons which carry a neutral Dirac fermion zero mode. The superconducting proximity effect induces "tunneling" between "layers" which leads to topological phase transitions whereby the Dirac fermion zero mode fractionalizes and Majorana fermions emerge in the edge states. The charge e/2 vortex excitation carrying a Majorana zero mode is a non-Abelian anyon. The proximity effect can also drive a conventional insulator into a quantum anomalous Hall effect state with a Majorana edge mode and the non-Abelian vortex excitations.
11345528
Topologization of electron liquids with Chern-Simons theory and quantum computation
A semiconductor integrated circuit is provided in which a space for accommodating a light emitting element driver circuit or a current detector circuit for detecting a current from a light receiving element can be reduced even if the number of channels connecting between a plurality of devices each having a semiconductor integrated circuit used therein. A signal source circuit 21, a light emitting element driver circuit 22 for supplying a signal outputted from the signal source circuit to a light emitting element 11 as a drive signal, and a light emitting element connecting terminal 23 connected to the output end of the driver circuit are integrally formed on one semiconductor chip of CMOS structure which is used as a semiconductor integrated circuit 20 of the transmitting side device A. A light receiving element connecting terminal 33 supplied with a current outputted from a light receiving element 15, a current detector circuit 32 the input end of which is connected to the connecting terminal, and a signal processing circuit 31 for receiving a signal outputted from the current detector circuit to process it in a predetermined manner are integrally formed on one semiconductor chip of CMOS structure which is used as a semiconductor integrated circuit 30 of the receiving side device B.
19017470
Topological properties of Abelian and non-Abelian quantum Hall states classified using patterns of zeros
It has been shown that different Abelian and non-Abelian fractional quantum Hall states can be characterized by patterns of zeros described by sequences of integers ${{S}_{a}}$. In this paper, we will show how to use the data ${{S}_{a}}$ to calculate various topological properties of the corresponding fraction quantum Hall state, such as the number of possible quasiparticle types and their quantum numbers, as well as the actions of the quasiparticle tunneling and modular transformations on the degenerate ground states on torus.
118873737
Laminar plasma dynamos
A new kind of dynamo utilizing flowing laboratory plasmas has been identified. The conversion of plasma kinetic energy to magnetic energy is verified numerically by kinematic dynamo simulations for magnetic Reynolds numbers above 210. As opposed to intrinsically-turbulent liquid-sodium dynamos, the proposed plasma dynamo corresponds to laminar flow topology. Modest plasma parameters (1–20 eV temperatures, 1019–1020 m−3 densities in 0.3–1.0 m scale-lengths driven by velocities on the order of the Alfven critical ionization velocity) self-consistently satisfy the conditions needed for the magnetic field amplication. Growth rates for plasma dynamos are obtained numerically with different geometry and magnetic Reynolds numbers. Magnetic-field-free coaxial plasma guns can be used to sustain the plasma flow and the dynamo.
17254631
Analysis of Y(4660) and related bound states with QCD sum rules
In this article, we take the vector charmonium-like state Y (4660) as a ψ′f0(980) bound state (irrespective of the hadro-charmonium and the molecular state) tentatively, study its mass using the QCD sum rules, the numerical value MY = 4.71 ± 0.26 GeV is consistent with the experimental data. Considering the SU(3) symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states ψσ(400 − 1200), Υ′′′f0(980) and Υσ(400 − 1200) with the QCD sum rules, and make reasonable predictions for their masses. PACS number: 12.39.Mk, 12.38.Lg