Institute for Advanced Study, Tsinghua University, Beijing 100084, China.
Phys Rev Lett. 2014 Apr 11;112(14):143004. doi: 10.1103/PhysRevLett.112.143004. Epub 2014 Apr 8.
In this Letter we consider spinless Fermi gases placed inside a cavity and study the critical strength of a pumping field for driving a superradiance transition. We emphasize that the Fermi surface nesting effect can strongly enhance the superradiance tendency. Around certain fillings, when the Fermi surface is nearly nested with a relevant nesting momentum, the susceptibility of the system toward a checkboard density-wave ordered state is greatly enhanced in comparison with a Bose gas with the same density, because of which a much smaller (sometime even vanishingly small) critical pumping field strength can give rise to superradiance. This effect leads to interesting reentrance behavior and a topologically distinct structure in the phase diagram. Away from these fillings, the Pauli exclusion principle brings about the dominant effect for which the critical pumping strength is lowered in the low-density regime and increased in the high-density regime. These results open the prospect of studying the rich phenomena of degenerate Fermi gases in a cavity.
在这封信件中，我们考虑了处于腔体内的无自旋费米气体，并研究了驱动超辐射跃迁的泵浦场的临界强度。我们强调，费米面嵌套效应可以显著增强超辐射倾向。在某些填充情况下，当费米面几乎与相关的嵌套动量嵌套时，与具有相同密度的玻色气体相比，系统对棋盘状密度波有序态的磁化率大大增强，因此，更小的（有时甚至是零）临界泵浦场强度就可以引发超辐射。这种效应导致了有趣的再进入行为和相图中拓扑上不同的结构。在这些填充情况之外，泡利不相容原理起着主导作用，导致在低密度区域中降低了临界泵浦强度，而在高密度区域中增加了临界泵浦强度。这些结果为在腔体内研究简并费米气体的丰富现象开辟了前景。
