200 research outputs found
Momentum-space Aharonov-Bohm interferometry in Rashba spin-orbit coupled Bose-Einstein condensates
Since the recent experimental realization of synthetic Rashba spin-orbit
coupling paved a new avenue for exploring and engineering topological phases in
ultracold atoms, a precise, solid detection of Berry phase has been desired for
unequivocal characterization of system topology. Here, we propose a scheme to
conduct momentum-space Aharonov-Bohm interferometry in a Rashba spin-orbit
coupled Bose-Einstein condensate with a sudden change of in-plane Zeeman field,
capable of measuring the Berry phase of Rashba energy bands. We find that the
Berry phase with the presence of a Dirac point is directly revealed by a robust
dark interference fringe, and that as a function of external Zeeman field is
characterized by the contrast of fringes. We also build a variational model
describing the interference process with semiclassical equations of motion of
essential dynamical quantities, which lead to agreeable trajectories and
geometric phases with the real-time simulation of Gross-Pitaevskii equation.
Our study would provide timely guidance for the experimental detection of Berry
phase in ultracold atomic systems and help further investigation on their
interference dynamics in momentum space.Comment: 9 pages, 6 figure
Non-Hermitian Disorder-induced Topological insulators
Recent studies of disorder or non-Hermiticity induced topological insulators
inject new ingredients for engineering topological matter. Here we consider the
effect of purely non-Hermitian disorders, a combination of these two
ingredients, in a 1D chiral symmetric lattice with disordered gain and loss.
The increasing disorder strength can drive a transition from trivial to
topological insulators, characterizing by the change of topological winding
number defined by localized states in the gapless and complex bulk spectra. The
non-Hermitian critical behaviors are characterized by the biorthogonal
localization length of zero energy edge modes, which diverges at the critical
transition point and establishes the bulk-edge correspondence. Furthermore, we
show that the bulk topology may be experimentally accessed by measuring the
biorthogonal chiral displacement , which converges to the winding
number through time-averaging and can be extracted from proper
Ramsey-interference sequences. We propose a scheme to implement and probe such
non-Hermitian disorder driven topological insulators using photons in coupled
micro-cavities.Comment: 4 pages, 5 figures and Supplementary Material
- …