Mun Jongchul, Medley Patrick, Campbell Gretchen K, Marcassa Luis G, Pritchard David E, Ketterle Wolfgang
MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, MIT, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2007 Oct 12;99(15):150604. doi: 10.1103/PhysRevLett.99.150604.
The stability of superfluid currents in a system of ultracold bosons was studied using a moving optical lattice. Superfluid currents in a very weak lattice become unstable when their momentum exceeds 0.5 recoil momentum. Superfluidity vanishes already for zero momentum as the lattice deep reaches the Mott insulator (MI) phase transition. We study the phase diagram for the disappearance of superfluidity as a function of momentum and lattice depth between these two limits. Our phase boundary extrapolates to the critical lattice depth for the superfluid-to-MI transition with 2% precision. When a one-dimensional gas was loaded into a moving optical lattice a sudden broadening of the transition between stable and unstable phases was observed.
利用移动光学晶格研究了超冷玻色子系统中超流电流的稳定性。当超流电流的动量超过0.5反冲动量时，在非常弱的晶格中的超流电流会变得不稳定。当晶格深度达到莫特绝缘体（MI）相变时，即使动量为零，超流性也会消失。我们研究了超流性消失的相图，它是这两个极限之间动量和晶格深度的函数。我们的相边界外推到超流到MI转变的临界晶格深度，精度为2%。当一维气体加载到移动光学晶格中时，观察到稳定相和不稳定相之间的转变突然变宽。
