2,296 research outputs found
Simulating Z_2 topological insulators with cold atoms in a one-dimensional optical lattice
We propose an experimental scheme to simulate and detect the properties of
time-reversal invariant topological insulators, using cold atoms trapped in
one-dimensional bichromatic optical lattices. This system is described by a
one-dimensional Aubry-Andre model with an additional SU(2) gauge structure,
which captures the essential properties of a two-dimensional Z2 topological
insulator. We demonstrate that topologically protected edge states, with
opposite spin orientations, can be pumped across the lattice by sweeping a
laser phase adiabatically. This process constitutes an elegant way to transfer
topologically protected quantum states in a highly controllable environment. We
discuss how density measurements could provide clear signatures of the
topological phases emanating from our one-dimensional system.Comment: 5 pages +, 3 figures, to appear in Physical Review
Probing Half-odd Topological Number with Cold Atoms in a Non-Abelian Optical Lattice
We propose an experimental scheme to probe the contribution of a single Dirac
cone to the Hall conductivity as half-odd topological number sequence. In our
scheme, the quantum anomalous Hall effect as in graphene is simulated with cold
atoms trapped in an optical lattice and subjected to a laser-induced
non-Abelian gauge field. By tuning the laser intensity to change the gauge
flux, the energies of the four Dirac points in the first Brillouin zone are
shifted with each other and the contribution of the single Dirac cone to the
total atomic Hall conductivity is manifested. We also show such manifestation
can be experimentally probed with atomic density profile measurements.Comment: 5 pages, 3 figure
Simulation and Detection of Photonic Chern Insulators in One-Dimensional Circuit Quantum Electrodynamics Lattice
We introduce a simple method to realize and detect photonic topological Chern
insulators with one-dimensional circiut quantum electrodynamics arrays. By
periodically modulating the couplings of the array, we show that this
one-dimensional model can be mapped into a two-dimensional Chern insulator
model. In addition to allowing the study of photonic Chern insulators, this
approach also provides a natural platform to realise experimentally Laughlin's
pumping argument. Based on scattering theory of topological insulators and
input-output formalism, we show that the photonic edge state can be probed
directly and the topological invariant can be detected from the winding number
of the reflection coefficient phase.Comment: 5 pages, 3 figure
Valley-dependent gauge fields for ultracold atoms in square optical superlattices
We propose an experimental scheme to realize the valley-dependent gauge
fields for ultracold fermionic atoms trapped in a state-dependent square
optical lattice. Our scheme relies on two sets of Raman laser beams to engineer
the hopping between adjacent sites populated by two-component fermionic atoms.
One set of Raman beams are used to realize a staggered \pi-flux lattice, where
low energy atoms near two inequivalent Dirac points should be described by the
Dirac equation for spin-1/2 particles. Another set of laser beams with proper
Rabi frequencies are added to further modulate the atomic hopping parameters.
The hopping modulation will give rise to effective gauge potentials with
opposite signs near the two valleys, mimicking the interesting strain-induced
pseudo-gauge fields in graphene. The proposed valley-dependent gauge fields are
tunable and provide a new route to realize quantum valley Hall effects and
atomic valleytronics.Comment: 5+ pages, 2 figures; language polished, references and discussions
added; accepted by PR
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