Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userBehavior of heat capacity of an attractive Bose-Einstein Condensate approaching collapse
383
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report calculation of heat capacity of an attractive Bose-Einstein condensate, with the number N of bosons increasing and eventually approaching the critical number Ncr for collapse, using the correlated potential harmonics (CPH) method. Boson pairs interact via the realistic van der Waals potential. It is found that the transition temperature Tc increases initially slowly, then rapidly as N becomes closer to Ncr . The peak value of heat capacity for a fixed N increases slowly with N, for N far away from Ncr . But after reaching a maximum, it starts decreasing when N approaches Ncr . The effective potential calculated by CPH method provides an insight into this strange behavior.
rate research
Read More
We study the dynamics of a soliton-impurity system modeled in terms of a binary Bose-Einstein condensate. This is achieved by `switching off one of the two self-interaction scattering lengths, giving a two component system where the second component is trapped entirely by the presence of the first component. It is shown that this system possesses rich dynamics, including the identification of unusual `weak dimers that appear close to the zero inter-component scattering length. It is further found that this system supports quasi-stable trimers in regimes where the equivalent single-component gas does not, which is attributed to the presence of the impurity atoms which can dynamically tunnel between the solitons, and maintain the required phase differences that support the trimer state.
We report on the observation of the confinement-induced collapse dynamics of a dipolar Bose-Einstein condensate (dBEC) in a one-dimensional optical lattice. We show that for a fixed interaction strength the collapse can be initiated in-trap by lowering the lattice depth below a critical value. Moreover, a stable dBEC in the lattice may become unstable during the time-of-flight dynamics upon release, due to the combined effect of the anisotropy of the dipolar interactions and inter-site coherence in the lattice.
We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential of an optical-box trap. We characterise the critical point for collapse and the collapse dynamics, observing universal behaviour in agreement with theoretical expectations. Most importantly, we observe a clear experimental signature of the counterintuitive weak collapse, namely that making the system more unstable can result in a smaller particle loss. We experimentally determine the scaling laws that govern the weak-collapse atom loss, providing a benchmark for the general theories of nonlinear wave phenomena.
We report on the production of a $^{41}$K-$^{87}$Rb dual-species Bose-Einstein condensate with tunable interspecies interaction and we study the mixture in the attractive regime, i.e. for negative values of the interspecies scattering length $a_{12}$. The binary condensate is prepared in the ground state and confined in a pure optical trap. We exploit Feshbach resonances for tuning the value of $a_{12}$. After compensating the gravitational sag between the two species with a magnetic field gradient, we drive the mixture into the attractive regime. We let the system to evolve both in free space and in an optical waveguide. In both geometries, for strong attractive interactions, we observe the formation of self-bound states, recognizable as quantum droplets. Our findings prove that robust, long-lived droplet states can be realized in attractive two-species mixtures, despite the two atomic components may experience different potentials.
We theoretically show that the topology of a non-simply-connected annular atomic Bose-Einstein condensate enforces the inner surface waves to be always excited with outer surface excitations and that the inner surface modes are associated with induced vortex dipoles unlike the surface waves of a simply-connected one with vortex monopoles. Consequently, under stirring to drive an inner surface wave, a peculiar population oscillation between the inner and outer surface is generated regardless of annulus thickness. Moreover, a new vortex nucleation process by stirring is observed that can merge the inner vortex dipoles and outer vortex into a single vortex inside the annulus. The energy spectrum for a rotating annular condensate with a vortex at the center also reveals the distinct connection of the Tkachenko modes of a vortex lattice to its inner surface excitations.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
