April 11, 2011 Wednesday 15:30
Menderes Işkın, Koç University
Spin-orbit coupled Fermi gases: story of the topological rings and spheres

Abstract:With the ultimate success of techniques for trapping and cooling atomic gases developed and improved gradually since the 1980’s, atomic Fermi gases have emerged as unique testing grounds for many theories of exotic matter in nature, allowing for the creation of complex yet very accessible and controllable many-body quantum systems. For instance, a major breakthrough was achieved with the variation of the attractive interaction between atoms from two hyperfine states of Lithium-6 (or Potassium-40). The tuning of interactions permits the ground state of the system to evolve smoothly from a weak coupling Bardeen-Cooper-Schrieffer (BCS) limit of largely overlapping Cooper pairs to a strong coupling regime of tightly-bound bosonic molecules, which undergo Bose-Einstein condensation (BEC). Given that the recent experimental studies on spin-orbit coupled Bose gases had a great success, one of the current frontiers in cold atom research is the study of spin-orbit coupled Fermi gases. In this talk, following an overview of earlier theoretical and experimental works on the usual BCS-BEC crossover problem, I will present our new results for the spin-orbit coupled systems. I will analyze both the ground state and finite temperature phase diagrams for uniform systems [1]. In particular, I will show that the topological structure of the ground-state phase diagrams is quite robust against the effects of anisotropy of the spin-orbit coupling. I will also show that the critical condensation temperature increases considerably in the molecular BEC limit. Depending on my timing, I may also present our very recent results on the vortex core and edge states in these systems.
[1] M. Iskin and A. L. Subasi, Phys. Rev. Lett. 107, 050402 (2011); and Phys. Rev. A 84, 043621 (2011).

Menderes Iskin was born in Tokat, where he also attended Namik Kemal and Melik Ahmet Gazi Elementary Schools. He moved to Istanbul in August 1989, and graduated from Kadikoy Anatolian High School with honors in June 1997. Upon graduation from high school, he moved to Ankara, and entered Bilkent University in September 1997, where he received the Bachelor of Science degree in Physics with high honors in May 2002. The following August, he moved to Atlanta, Georgia and entered Georgia Institute of Technology, where he received a Doctor of Philosophy degree in August 2007. He then moved to Gaithersburg, Maryland and worked 2 years as a postdoc researcher at the Joint Quantum Institute, which is a joint institution between National Institute of Science and Technology (NIST) and University of Maryland. Having completed his PhD and postdoc studies abroad, he returned back to Istanbul in August 2009 and joined Koc University as an Assistant Professor of Physics. His research interests is mainly focused on the quantum phases of two-species Fermi-Fermi, Bose-Bose and Bose-Fermi mixtures of atomic gases at ultracold temperatures, and it is currently supported by a European Commission’s Marie Curie International Reintegration Grant (FP7-PEOPLE-IRG-2010-268239), Scientific and Technological Research Council of Turkey’s Career Grant (TUBITAK 3501-110T839), and the Turkish Academy of Science’s TUBA-GEBIP award.