205 research outputs found
Escape Time Characterization of Pendular Fabry-Perot
We show that an escape from the potential minimum of Fabry-Perot
interferometers can be detected measuring the associated sudden change of
reflectivity. We demonstrate that the loss of information that occurs retaining
only the sequence of escapes, rather than the full trajectory, can be very mild
and can lead to an effective method to reveal the noise intensity or the
presence of a coherent signal
Domain walls and bubble-droplets in immiscible binary Bose gases
The existence and stability of domain walls (DWs) and bubble-droplet (BD)
states in binary mixtures of quasi-one-dimensional ultracold Bose gases with
inter- and intra-species repulsive interactions is considered. Previously, DWs
were studied by means of coupled systems of Gross-Pitaevskii equations (GPEs)
with cubic terms, which model immiscible binary Bose-Einstein condensates
(BECs). We address immiscible BECs with two- and three-body repulsive
interactions, as well as binary Tonks--Girardeau (TG) gases, using systems of
GPEs with cubic and quintic nonlinearities for the binary BEC, and coupled
nonlinear Schr\"{o}dinger equations with quintic terms for the TG gases. Exact
DW\ solutions are found for the symmetric BEC mixture, with equal intra-species
scattering lengths. Stable asymmetric DWs in the BEC mixtures with dissimilar
interactions in the two components, as well as of symmetric and asymmetric DWs
in the binary TG gas, are found by means of numerical and approximate
analytical methods. In the BEC system, DWs can be easily put in motion by phase
imprinting. Combining a DW and anti-DW on a ring, we construct BD states for
both the BEC and TG models. These consist of a dark soliton in one component
(the "bubble"), and a bright soliton (the "droplet") in the other. In the BEC
system, these composite states are mobile too.Comment: Phys. Rev. A, in pres
Observation of progressive motion of ac-driven solitons
We report the first experimental observation of phase-locked motion of a
topological soliton at a nonzero average velocity in a periodically modulated
lossy medium, under the action of an ac force with no dc component [the effect
was predicted by G. Filatrella, B.A. Malomed, and R.D. Parmentier, Phys. Lett.
A 198, 43 (1995)]. The velocity is related by a resonant condition to the
driving frequency. The observation is made in terms of the current-voltage,
I(V), characteristics for a fluxon trapped in an annular Josephson junction
placed into dc magnetic field. Large zero-crossing constant-voltage steps,
exactly corresponding to the resonantly locked soliton motion at different
orders of the resonance, are found on the experimental I(V) curves. A measured
dependence of the size of the steps vs. the external magnetic field is in good
agreement with predictions of an analytical model based on the balance equation
for the fluxon's energy. The effect has a potential application as a
low-frequency voltage standard. The work was supported by a grant from the
German-Israeli Foundation.Comment: Physical Review B, in press (Rapid Communication
- …