اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStability of $p$-orbital Bose-Einstein condensates in optical checkerboard and square lattices
99
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We investigate $p$-orbital Bose-Einstein condensates in both the square and checkerboard lattice by numerically solving the Gross-Pitaevskii equation. The periodic potential for the latter lattice is taken exactly from the recent experiment [Nature Phys. 7, 147 (2011)]. It is confirmed that the staggered orbital-current state is the lowest-energy state in the $p$ band. Our numerical calculation further reveals that for both lattices the staggered $p$-orbital state suffers Landau instability but the situation is remarkably different for dynamical instability. A dynamically stable parameter region is found for the checkerboard lattice, but not for the square.
قيم البحث
اقرأ أيضاً
We investigate the quantum fluctuation effects in the vicinity of the critical point of a $p$-orbital bosonic system in a square optical lattice using Wilsonian renormalization group, where the $p$-orbital bosons condense at nonzero momenta and displ
ay rich phases including both time-reversal symmetry invariant and broken BEC states. The one-loop renormalization group analysis generates corrections to the mean-field phase boundaries. We also show the quantum fluctuations in the $p$-orbital system tend to induce the ordered phase but not destroy it via the the Coleman-Weinberg mechanism, which is qualitative different from the ordinary quantum fluctuation corrections to the mean-field phase boundaries in $s$-orbital systems. Finally we discuss the observation of these phenomena in the realistic experiment.
We analyze time-of-flight absorption images obtained with dilute Bose-Einstein con-densates released from shaken optical lattices, both theoretically and experimentally. We argue that weakly interacting, ultracold quantum gases in kilohertz-driven op
tical potentials constitute equilibrium systems characterized by a steady-state distri-bution of Floquet-state occupation numbers. Our experimental results consistently indicate that a driven ultracold Bose gas tends to occupy a single Floquet state, just as it occupies a single energy eigenstate when there is no forcing. When the driving amplitude is sufficiently high, the Floquet state possessing the lowest mean energy does not necessarily coincide with the Floquet state connected to the ground state of the undriven system. We observe strongly driven Bose gases to condense into the former state under such conditions, thus providing nontrivial examples of dressed matter waves.
Binary mixtures of Bose-Einstein condensates trapped in deep optical lattices and subjected to equal contributions of Rashba and Dresselhaus spin-orbit coupling (SOC), are investigated in the presence of a periodic time modulation of the Zeeman field
. SOC tunability is explicitly demonstrated by adopting a mean-field tight-binding model for the BEC mixture and by performing an averaging approach in the strong modulation limit. In this case, the system can be reduced to an unmodulated vector discrete nonlinear Schrodinger equation with a rescaled SOC tunning parameter $alpha$, which depends only on the ratio between amplitude and frequency of the applied Zeeman field. The dependence of the spectrum of the linear system on $alpha$ has been analytically characterized. In particular, we show that extremal curves (ground and highest excited states) of the linear spectrum are continuous piecewise functions (together with their derivatives) of $alpha$, which consist of a finite number of decreasing band lobes joined by constant lines. This structure also remains in presence of not too large nonlinearities. Most important, the interactions introduce a number of localized states in the band-gaps that undergo change of properties as they collide with band lobes. The stability of ground states in the presence of the modulating field has been demonstrated by real time evolutions of the original (un-averaged) system. Localization properties of the ground state induced by the SOC tuning, and a parameter design for possible experimental observation have also been discussed.
We investigate a Bose Einstein condensate held in a 1D optical lattice whose phase undergoes a fast oscillation using a statistical analysis. The averaged potential experienced by the atoms boils down to a periodic potential having the same spatial p
eriod but with a renormalized depth. However, the atomic dynamics also contains a emph{micromotion} whose main features are revealed by a Kolmorogov-Smirnov analysis of the experimental momentum distributions. We furthermore discuss the impact of the micromotion on a quench process corresponding to a proper sudden change of the driving amplitude which reverses the curvature of the averaged potential.
Vortex lattices in rapidly rotating Bose--Einstein condensates are systems of topological excitations that arrange themselves into periodic patterns. Here we show how phase-imprinting techniques can be used to create a controllable number of defects
in these lattices and examine the resulting dynamics. Even though we describe our system using the mean-field Gross--Pitaevskii theory, the full range of many particle effects among the vortices can be studied. In particular we find the existence of localized vacancies that are quasi-stable over long periods of time, and characterize the effects on the background lattice through use of the orientational correlation function, and Delaunay triangulation.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
