7,386 research outputs found
Recovery of Sparse Signals Using Multiple Orthogonal Least Squares
We study the problem of recovering sparse signals from compressed linear
measurements. This problem, often referred to as sparse recovery or sparse
reconstruction, has generated a great deal of interest in recent years. To
recover the sparse signals, we propose a new method called multiple orthogonal
least squares (MOLS), which extends the well-known orthogonal least squares
(OLS) algorithm by allowing multiple indices to be chosen per iteration.
Owing to inclusion of multiple support indices in each selection, the MOLS
algorithm converges in much fewer iterations and improves the computational
efficiency over the conventional OLS algorithm. Theoretical analysis shows that
MOLS () performs exact recovery of all -sparse signals within
iterations if the measurement matrix satisfies the restricted isometry property
(RIP) with isometry constant The recovery performance of MOLS in the noisy scenario is also
studied. It is shown that stable recovery of sparse signals can be achieved
with the MOLS algorithm when the signal-to-noise ratio (SNR) scales linearly
with the sparsity level of input signals
Exotic Haldane Superfluid Phase of Soft-Core Bosons in Optical Lattices
We propose to realize an exotic Haldane superfluid (HSF) phase in an extended
Bose-Hubbard model on the two-leg ladder (i.e., a two-species mixture of
interacting bosons). The proposal is confirmed by means of large-scale quantum
Monte Carlo simulations, with a significant part of the ground-state phase
diagram being revealed. Most remarkably, the newly discovered HSF phase
features both superfluidity and the non-local topological Haldane order. The
effects induced by varying the number of legs are furthermore explored. Our
results shed light on how topological superfluid emerges in bosonic systems.Comment: 5 pages, 6 figures; accepted for publication in Physical Review B
(April 29, 2016
Bosonic Haldane insulator in the presence of local disorder: A quantum Monte Carlo study
The Haldane phase (HP) is a paradigmatic example of symmetry protected
topological phase. We explore how the bosonic HP behaves in the presence of
local disorder, employing quantum Monte Carlo simulations of an extended
Bose-Hubbard model subject to uncorrelated, quenched disorders. We find that
the HP is robust against a weak disorder and the non-local string order of HP
exhibits a reentrant behavior. Besides, a direct transition between the HP and
superfluid phase is uncovered. A significant part of the ground-state phase
diagram is established for the model, unveiling the location of HP surrounded
by Bose glass, charge density wave and superfluid phases. We also mention a
possible experimental scheme with optical lattice emulator to realize the
present findings.Comment: 6 pages, 5 figure
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