Seminar
Tuesday, 06 March, 2012
Group Seminar LMU: Fermi liquid of two-dimensional polar molecules
Tuesday, 06.03.2012 10:00 a.m. (s.t.) in H107, Fakultät für Physik, LMU
Zhenkai Lu Max-Planck-Insitut für Quantenoptik, Garching
In this talk, I will present my theoretical studies with Prof. Gora Shlyapnikov on two- dimensional polar molecules.
The non-trivial beyond mean-field corrections to the ground state energy of a weakly short- range interacting Bose/Fermi gas which were first calculated by C. N. Yang, T. D. Lee and K. Huang in 1950s provides one of the few quantitative test for many-body quantum field theory. The methods were refined by Bogliubov (Bose case), Abrikosov-Khalatnikov (Fermi case) based on Landauʼs Fermi liquid theory. Recently, those predictions were confirmed in experiments [1]. Similar tests are interesting in the case of systems with long-range dipolar interaction. We developed a theoretical approach to this problem.
I will first briefly review Landauʼs Fermi liquid theory and historical efforts on calculating Lee-Huang-Yang coefficient. Then, I will present a systematic way to solve the two-body scattering problem with dipole-dipole interaction in 2D. Following the idea of Abrikosov- Khalatnikov, the compressibility, ground-state energy and effective mass are obtained analytically. We also study the collective excitations in the collisionless regime and stress that the existence of zero sound is a pure many-body effect [2]. Our analytical method can be extended to study the tilted dipolar system where the interaction is anisotropic. I will present our preliminary calculation results of this case [3].
In addition, dipole-induced resonances in 3D have been predicted theoretically. I will give some perspectives about few-body problems (three-body recombination,Efimov effects) of dipolar system near these resonances.
[1] N. Navon, S. Nascimbene, F. Chevy and C. Salomon The Equation of State of a Low- Temperature Fermi Gas with Tunable Interactions. Science 328, 729 (2010).
[2] Z.-K. Lu and G. V. Shlyapnikov Fermi liquid of two-dimensional polar molecules. Phys. Rev. A 85 023614 (2012).
[3] Z.-K. Lu and G. V. Shlyapnikov Collective excitations of two-dimensional polar molecules in the collisionless regime. (in preparation).