01747nas a2200157 4500008004100000245008800041210006900129260001500198300001100213490000700224520127000231100001801501700001501519700001901534856003601553 2016 eng d00aSudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep optical lattices0 aSuddenquench dynamics of BardeenCooperSchrieffer states in deep c2016/08/05 a0236070 v943 a
We determine the exact time evolution of an initial Bardeen-Cooper-Schrieffer (BCS) state of ultra-cold atoms in a hexagonal optical lattice. The dynamical evolution is triggered by ramping the lattice potential up, such that the interaction strength Uf is much larger than the hopping amplitude Jf. The quench initiates collective oscillations with frequency |Uf|/(2π) in the momentum occupation numbers and imprints an oscillating phase with the same frequency on the order parameter Δ. The latter is not reproduced by treating the time evolution in mean-field theory. The momentum density-density or noise correlation functions oscillate at frequency |Uf|/2π as well as its second harmonic. For a very deep lattice, with negligible tunneling energy, the oscillations of momentum occupation numbers are undamped. Non-zero tunneling after the quench leads to dephasing of the different momentum modes and a subsequent damping of the oscillations. This occurs even for a finite-temperature initial BCS state, but not for a non-interacting Fermi gas. We therefore propose to use this dephasing to detect a BCS state. Finally, we predict that the noise correlation functions in a honeycomb lattice will develop strong anti-correlations near the Dirac point.
1 aNuske, Marlon1 aMathey, L.1 aTiesinga, Eite uhttp://arxiv.org/abs/1602.00979