Interaction-Assisted Quantum Tunneling of a Bose-Einstein Condensate Out of a Single Trapping Well

Abstract

We experimentally study tunneling of Bose-condensed ^{87}Rb atoms prepared in a quasibound state and observe a nonexponential decay caused by interatomic interactions. A combination of a magnetic quadrupole trap and a thin 1.3 μm barrier created using a blue-detuned sheet of light is used to tailor traps with controllable depth and tunneling rate. The escape dynamics strongly depend on the mean-field energy, which gives rise to three distinct regimes-classical spilling over the barrier, quantum tunneling, and decay dominated by background losses. We show that the tunneling rate depends exponentially on the chemical potential. Our results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation.

Macroscopic quantum escape of Bose-Einstein condensates: Analysis of experimentally realizable quasi-one-dimensional traps

“…Coherence of the trapped atoms suggests that our mean-field analysis could have some extension into the many-body regime. In contrast to non-interacting predictions, the mean-field decay process has been predicted and measured as non-exponential in time [22,40]. A current experiment did not have the necessary resolution to separate out mean-field and possible many-body effects [10], and these quasi-1D experiments are a possible avenue, i.e., performing interference measurement of the escaped atoms.…”

“…MQT in double-well systems is well established in BECs for both the AC and DC Josephson effects [20,21], with interactions allowing for self-trapping regimes and decreased oscillation period by an order of magnitude. Furthermore, the first mean-field or semi-classical observation of quantum tunneling escape has been made [22], where interactions produced non-exponential decay.…”

Quantum tunneling dynamics of an interacting Bose-Einstein condensate through a Gaussian barrier

“…imentally, with the effect of interactions on the transmission coefficient demonstrated [24][25][26]. An increase in the transmission rate with atom number has been shown using numerical simulations [27] and demonstrated exper-imentally [28], while the dependence of transmission on barrier height has also been experimentally verified [29].…”

Entangled Dynamics in Macroscopic Quantum Tunneling of Bose-Einstein Condensates

“…Macroscopic quantum tunneling (MQT), the aggregate tunneling behavior of a quantum manybody wavefunction, has been demonstrated in many condensed matter systems [5,6] and is one of the remarkable features of Bose-Einstein Condensates (BECs), ranging from Landau-Zener tunneling in tilted optical lattices [7] to the AC and DC Josephson effects in double wells [8,9], as well as their quantum entangled generalizations [10]. The original vision of quantum tunneling was in fact the quantum escape or quasibound problem by Gurney and Condon in 1929 [1], and recently the first meanfield or semiclassical observation of quantum escape has been made in Toronto [11]. However, with the rise of entanglement as a key perspective on quantum manybody physics, the advent of powerful entangled dynamics matrix-product-state (MPS) methods [12,13], and the possibility of observing the moment-to-moment time evolution of quasibound tunneling dynamics directly in the laboratory [11,[14][15][16][17] it is the right time to revisit quantum escape.…”

“…The original vision of quantum tunneling was in fact the quantum escape or quasibound problem by Gurney and Condon in 1929 [1], and recently the first meanfield or semiclassical observation of quantum escape has been made in Toronto [11]. However, with the rise of entanglement as a key perspective on quantum manybody physics, the advent of powerful entangled dynamics matrix-product-state (MPS) methods [12,13], and the possibility of observing the moment-to-moment time evolution of quasibound tunneling dynamics directly in the laboratory [11,[14][15][16][17] it is the right time to revisit quantum escape. In this Letter, we take advantage of the powerful new toolset for quantum many-body simulations [13, 18] to show that the many-body quantum tunneling problem differs in key respects from our expectations from semiclassical and other well-established approaches to tunneling.…”