اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدNumber of closed-channel molecules in the BEC-BCS crossover
153
0
0.0
(
0
)
تأليف
Felix Werner
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Using a two-channel model, we show that the number of closed channel molecules in a two-component Fermi gas close to a Feshbach resonance is directly related to the derivative of the energy of the gas with respect to the inverse scattering length. We extract this quantity from the fixed node Monte-Carlo equation of state and we compare to the number of closed channel molecules measured in the Rice experiment with lithium [Partridge et al., Phys. Rev. Lett. 95, 020404 (2005)]. We also discuss the effect of a difference between the trapping potentials seen by a closed-channel molecule and by an open-channel pair of atoms in terms of an effective position-dependent scattering length.
قيم البحث
اقرأ أيضاً
We study the short-time dynamics of a degenerate Fermi gas positioned near a Feshbach resonance following an abrupt jump in the atomic interaction resulting from a change of external magnetic field. We investigate the dynamics of the condensate order
parameter and pair wavefunction for a range of field strengths. When the abrupt jump is sufficient to span the BCS to BEC crossover, we show that the rigidity of the momentum distribution precludes any atom-molecule oscillations in the entrance channel dominated resonances observed in the 40K and 6Li. Focusing on material parameters tailored to the 40K Feshbach resonance system at 202.1 gauss, we comment on the integrity of the fast sweet projection technique as a vehicle to explore the condensed phase in the crossover region
Critical velocities have been observed in an ultracold superfluid Fermi gas throughout the BEC-BCS crossover. A pronounced peak of the critical velocity at unitarity demonstrates that superfluidity is most robust for resonant atomic interactions. Cri
tical velocities were determined from the abrupt onset of dissipation when the velocity of a moving one dimensional optical lattice was varied. The dependence of the critical velocity on lattice depth and on the inhomogeneous density profile was studied.
We perform a variational quantum Monte Carlo simulation of the transition from a Bardeen-Cooper-Schrieffer superfluid (BCS) to a Bose-Einstein condensate (BEC) at zero temperature. The model Hamiltonian involves an attractive short range two body int
eraction and the atoms number $2N =330$ is chosen so that, in the non-interacting limit, the ground state function corresponds to a closed shell configuration. The system is then characterized by the s-wave scattering length $a$ of the two-particle collisions in the gas, which is varied from negative to positive values, and the Fermi wave number $k_F$. Based on an extensive analysis of the s-wave two-body problem, one parameter variational many-body wave functions are proposed to describe the ground state of the interacting Fermi gas from BCS to BEC states. We exploit properties of antisymmetrized many-body functions to develop efficient techniques that permit variational calculations for a large number of particles. It is shown that a virial relation between the energy per particle and the trapping energy is approximately valid for $-0.1<1/k_Fa<3.4$. The influence of the harmonic trap and the interaction potential as exhibited in two-body correlation functions is also analyzed.
We study collective excitation modes of a fermionic gas of $^6$Li atoms in the BEC-BCS crossover regime. While measurements of the axial compression mode in the cigar-shaped trap close to a Feshbach resonance confirm theoretical expectations, the rad
ial compression mode shows surprising features. In the strongly interacting molecular BEC regime we observe a negative frequency shift with increasing coupling strength. In the regime of a strongly interacting Fermi gas, an abrupt change in the collective excitation frequency occurs, which may be a signature for a transition from a superfluid to a collisionless phase.
We report on experimental studies on the collective behavior of a strongly interacting Fermi gas with tunable interactions and variable temperature. A scissors mode excitation in an elliptical trap is used to characterize the dynamics of the quantum
gas in terms of hydrodynamic or near-collisionless behavior. We obtain a crossover phase diagram for collisional properties, showing a large region where a non-superfluid strongly interacting gas shows hydrodynamic behavior. In a narrow interaction regime on the BCS side of the crossover, we find a novel temperature-dependent damping peak, suggesting a relation to the superfluid phase transition.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
