Fermions from Cold Atoms to Neutron Stars: Benchmarking the Many-Body Problem (INT-11-1)March 14 - May 20, 2011Michael McNeil Forbes, Aurel Bulgac, Alexandros Gezerlis, Gora V. Shlyapnikov, Tin-Lun (Jason) Ho, Martin W. Zwierlein
Pairing in low density fermion systems: Open problems
Symmetric (unpolarized) systems
- What is the size of the Cooper pair?
Nature 454, 739-743 (2008)
- Is there a pseudo-gap phase? What is the best way to put it in evidence experimentally?
- Response of a paired system to a weak external field, RF spectroscopy.
Asymmetric (polarized/imbalanced) systems
Son and Stephanov, 2005 Bulgac, Forbes, Schwenk, 2006
Gapless superfluid
LOFF
normal
Bulgac and Yoon, 2009
Going beyond the naïve BCS approximation (P-wave pairing)Going beyond the naïve BCS approximation (P-wave pairing)
BCS approx. (black)BCS approx. (black)
Eliashberg approx. (blue)Eliashberg approx. (blue)
Full momentum and frequency dependence of the self-Full momentum and frequency dependence of the self-consistent equations (red)consistent equations (red)
nb/nf = 2, 1, 0.5(from upper to lower panel)
5/32 2/3 23 (6 )
( , ) 5 2
ba b a
a
nE n n n g
m n
Bulgac, Forbes, 2008
LOFF at unitarity
5/23/2
2 2
2 2[ , ]
30b
a b aa
mP h
Next Frontier - Time-dependent probes