Density and Spin Linear Response of Atomic Fermi Superfluids with Population Imbalance in BCS-BEC Crossover

We present a theoretical study of the density and spin (representing the two components) linear response of Fermi superfluids with tunable attractive interactions and population imbalance. In both linear response theories, we find that the fluctuations of the order parameter must be treated on equal footing with the gauge transformations associated with the symmetries of the Hamiltonian so that important constraints including various sum rules can be satisfied. Both theories can be applied to the whole BCS-Bose-Einstein condensation crossover. The spin linear responses are qualitatively different with and without population imbalance because collective-mode effects from the fluctuations of the order parameter survive in the presence of population imbalance, even though the associated symmetry is not broken by the order parameter. Since a polarized superfluid becomes unstable at low temperatures in the weak and intermediate coupling regimes, we found that the density and spin susceptibilities diverge as the system approaches the unstable regime, but the emergence of phase separation preempts the divergence.Comment: 15 pages, 5 figure

Introduction to Asian Culture(s) and Globalization

Marshall McLuhan coined the term the global village associating globalized human experiences in an electronic age (4). Although transnational relations existed for many centuries, McLuhan predicted in the 1960s that new technologies not only facilitate the growth of international interconnectedness, cross-border exchanges, as well as trans-cultural phenomena, but also help foster cultural transactions. Referring to the dramatic and unprecedented break between the past and the present, tradition and modernity, Arjun Appadurai argues that media and migration have been two major forces impelling the circulation of world cultures (3). In the phenomenon of globalization, people from every part of the world tend to embrace the concepts of democracy, human rights, and technical assistance, but globalization did not and does not go smooth in all aspects of life. Globalization was originally characterized as a power to diminish the gap between the developed and developing worlds. However, there continue to be resistance against globalization because of the West\u27s — i.e., technologically and industrially advanced countries with now soft imperial agendas. As Fredric Jameson suggests, globalization has become a philosophical issue because through cultural adaption, integration, and transformation, globalization has triggered the development of mass culture and restructured the production of cultures in various ways (54-60)