Quantum tunneling of ultracold atoms in optical traps

Andrea Parlangeli

W. K. Hensinger, Hartmut Häffner, Antoine Browaeys +7 more

Binglu Wang, Yanhua Ma, Man Shen +1 more

We investigate the tunneling of ultracold atoms in optical traps by using the path-integral method. We obtain the decay rate for tunneling out of a single-well and discuss how the rate is affected by the level splitting caused by the presence of a second adjacent well. Our calculations show that the transition through the potential barrier can be divided into three regions: the quantum tunneling region, the thermally assisted region and the thermal activation region. The tunneling process is found to be a second-order transition. We also show that level splitting due to tunneling can increase the tunneling rate.

Jian-Hua Wu, Ran Qi, An-Chun Ji +1 more

We review our theoretical advances in quantum tunneling of Bose-Einstein condensates in optical traps and in microcavities. By employing a real physical system, the frequencies of the pseudo Goldstone modes in different phases between two optical traps are studied respectively, which are the crucial feature of the non-Abelian Josephson effect. When the optical lattices are under gravity, we investigate the quantum tunneling in the “Wannier-Stark localization” regime and “Landau-Zener tunneling” regime. We finally get the total decay rate and the rate is valid over the entire range of temperatures. At high temperatures, we show how the decay rate reduces to the appropriate results for the classical thermal activation. At intermediate temperatures, the results of the total decay rate are consistent with the thermally assisted tunneling. At low temperatures, we obtain the pure quantum tunneling ultimately. And we study the alternating-current and direct-current (ac and dc) photonic Josephson effects in two weakly linked microcavities containing ultracold two-level atoms, which allows for direct observation of the effects. This enables new investigations of the effect of many-body physics in strongly coupled atom-cavity systems and provides a strategy for constructing novel interference devices of coherent photons. In addition, we propose the experimental protocols to observe these quantum tunneling of Bose-Einstein condensates.

Roberto B. Diener

Pontificia Universidad Católica de Chile. Instituto de Física, E. Aguilera-Valdés

The thesis studies Photon-Assisted Tunneling (PAT) in a system of ultracold atoms in a triple-well potential, utilizing Bose-Hubbard and Gross-Pitaevskii models. Simulations reveal that an ac-driving field influence tunneling dynamics, enabling quantum self-trapping and PAT. The study extends to open quantum systems, analyzing PT-symmetric setups with balanced gain and loss, showcasing PAT’s role in quantum control and potential applications in ultracold atom systems and quantum optics.