Tunneling in Open Systems: Dynamics

Joachim Ankerhold

Y.-H. Kim, Ulrich Kuhl, H.-J. Stöckmann +1 more

We investigate the signatures of dynamical tunnelling in open quantum dots, by implementing a soft-walled microwave cavity as a novel analogue system. We explore the evidence for dynamical tunnelling by studying the evolution of the wavefunction phase as a function of frequency and show evidence for evanescent coupling to isolated orbits, including the existence of 'dirty' states in the wavefunction that are generated from a degenerate pair of 'clean' states when they are degraded by their tunnelling interaction. Our investigations provide a useful analogue of quantum transport in open quantum dots, and demonstrate the importance of dynamical tunnelling that arises from the mixed classical dynamics that is inherent to these structures.

Ángel S. Sanz, Salvador Miret-Artés

Axel U. J. Lode, Alexej I. Streltsov, Ofir E. Alon +1 more

We investigate the mechanism in the tunneling dynamics of open ultracold few-boson systems by numerically solving the time-dependent few-boson Schrödinger equation exactly. By starting from a weakly repulsive, initially coherent two-boson system we demonstrate that the decay dynamics incorporate fragmentation. The wavefunction of the tunneling state exhibits a pronounced dynamically-stable pattern which we explain by an analytical model. By studying more bosons and stronger interactions we arrive to the conclusion that the decay by tunneling is not a coherent process and exhibits a wealth of phenomena depending on the interaction between the particles.

Jacek Dobrzyniecki, Tomasz Sowiński

A comprehensive analysis of the dynamics of two Rydberg-dressed particles (bosons or fermions) tunneling from a potential well into open space is provided. We show that the dominant decay mechanism switches from sequential tunneling to pair tunneling when the interaction strength is tuned below a certain critical value. These critical values can be modified by tuning the effective range of the interaction potential. By comparing the dynamics of bosons and fermions, we show that there are significant differences between the two cases. In particular, increasing the interaction range modifies the tunneling rate in opposite ways for fermions and bosons. Furthermore, for the fermionic system much stronger attractive interactions are needed to achieve pair tunneling. The results provide insight into the dynamics of tunneling systems and, in light of recent realizations of tunneling few-body systems and Rydberg dressing of atoms, they offer promise for future experiments.