Geometric ``charge'' pumping with a Bose-Einstein condensate

Lauren Aycock, Dina Genkina, Seiji Sugawa +3 more

Padmakar V. Panat

Hsin I Lu, Max Schemmer, Lauren Aycock +3 more

We realized a quantum geometric "charge" pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global-topological-properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits nonquantized charge pumping set by local-geometrical-properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wave packet's position in each unit cell, i.e., the polarization.

Florian Meinert, K. S. Kleinbach, Felix B. Engel +3 more

Xiaoji Zhou, Xuzong Chen, Yiqiu Wang

S. Schuster, P. Wolf, Dag Schmidt +2 more

We experimentally investigate the dynamic instability of Bose-Einstein condensates in an optical ring resonator that is asymmetrically pumped in both directions. We find that, beyond a critical resonator-pump detuning, the system becomes stable regardless of the pump strength. Phase diagrams and quenching curves are presented and described by numerical simulations. We discuss a physical explanation based on a geometric interpretation of the underlying nonlinear equations of motion.