8 research outputs found
Topological Pumping over a Photonic Fibonacci Quasicrystal
Quasiperiodic lattices have recently been shown to be a non-trivial
topological phase of matter. Charge pumping -- one of the hallmarks of
topological states of matter -- was recently realized for photons in a
one-dimensional (1D) off-diagonal Harper model implemented in a photonic
waveguide array. The topologically nontrivial 1D Fibonacci quasicrystal (QC) is
expected to facilitate a similar phenomenon, but its discrete nature and lack
of pumping parameter hinder the experimental study of such topological effects.
In this work we overcome these obstacles by utilizing a family of topologically
equivalent QCs which ranges from the Fibonacci QC to the Harper model.
Implemented in photonic waveguide arrays, we observe the topological properties
of this family, and perform a topological pumping of photons across a Fibonacci
QC.Comment: 5 pages, 4 figures, comments are welcom
Quantum Walk of Two Interacting Bosons
We study the effect of interactions on the bosonic two-particle quantum walk
and its corresponding spatial correlations. The combined effect of interactions
and Hanbury-Brown Twiss interference results in unique spatial correlations
which depend on the strength of the interaction, but not on its sign. The
results are explained in light of the two-particle spectrum and the physics of
attractively and repulsively bound pairs. We experimentally measure the weak
interaction limit of these effects in nonlinear photonic lattices. Finally, we
discuss an experimental approach to observe the strong interaction limit using
single atoms in optical lattices.Comment: 4 pages, 5 figures. Comments wellcom
Topological States and Adiabatic Pumping in Quasicrystals
The unrelated discoveries of quasicrystals and topological insulators have in
turn challenged prevailing paradigms in condensed-matter physics. We find a
surprising connection between quasicrystals and topological phases of matter:
(i) quasicrystals exhibit nontrivial topological properties and (ii) these
properties are attributed to dimensions higher than that of the quasicrystal.
Specifically, we show, both theoretically and experimentally, that
one-dimensional quasicrystals are assigned two-dimensional Chern numbers and,
respectively, exhibit topologically protected boundary states equivalent to the
edge states of a two-dimensional quantum Hall system.We harness the topological
nature of these states to adiabatically pump light across the quasicrystal. We
generalize our results to higher-dimensional systems and other topological
indices. Hence, quasicrystals offer a new platform for the study of topological
phases while their topology may better explain their surface properties.Comment: 10 pages, 5 figures, 4 appendice
Observation of Topological Phase Transitions in Photonic Quasicrystals
Topological insulators and topological superconductors are distinguished by their bulk phase transitions and gapless states at a sharp boundary with the vacuum. Quasicrystals have recently been found to be topologically nontrivial. In quasicrystals, the bulk phase transitions occur in the same manner as standard topological materials, but their boundary phenomena are more subtle. In this Letter we directly observe bulk phase transitions, using photonic quasicrystals, by constructing a smooth boundary between topologically distinct one-dimensional quasicrystals. Moreover, we use the same method to experimentally confirm the topological equivalence between the Harper and Fibonacci quasicrystals.Israel Science Foundation (Grant 700822030182