7 research outputs found
Correlated metallic two particle bound states in quasiperiodic chains
Single particle states in a chain with quasiperiodic potential show a
metal-insulator transition upon the change of the potential strength. We
consider two particles with local interaction in the single particle insulating
regime. The two particle states change from being localized to delocalized upon
an increase of the interaction strength to a nonperturbative finite value. At
even larger interaction strength the states become localized again. This
transition of two particle bound states into a correlated metal is due to a
resonant mixing of the noninteracting two particle eigenstates. In the
discovered correlated metal states two particles move coherently together
through the whole chain, therefore contributing to a finite conductivity.Comment: 4 pages, 4 figure
Focusing of light energy inside a scattering medium by controlling the time-gated multiple light scattering
The efficient delivery of light energy is a prerequisite for non-invasive
imaging and stimulating of target objects embedded deep within a scattering
medium. However, injected waves experience random diffusion by multiple light
scattering, and only a small fraction reaches the target object. Here we
present a method to counteract wave diffusion and to focus multiplescattered
waves to the deeply embedded target. To realize this, we experimentally inject
light to the reflection eigenchannels of a specific flight time where most of
the multiple-scattered waves have interacted with the target object and
maximize the intensity of the returning multiple-scattered waves at the
selected time. For targets that are too deep to be visible by optical imaging,
we demonstrated a more than 10-fold enhancement in light energy delivery in
comparison with ordinary wave diffusion cases. This work will lay a foundation
for enhancing the working depth of imaging, sensing, and light stimulation