Control of Tunneling

Luís G. C. Rego, Sabas G. Abuabara, Víctor S. Batista

The feasibility of achieving coherent control of tunnelling dynamics, associated with electronic excitations in functionalized semiconductor nanostructures, is investigated. The coherent control scenario is based on the application of frequent stochastic unitary pulses, affecting the interference phenomena between electronic wave-packet components and consequently the overall electronic tunnelling dynamics without collapsing the coherent quantum evolution of the system. It is shown that tunnelling can be inhibited and eventually halted by sufficiently frequent pulse fields that exchange energy with the system but do not affect the potential energy tunnelling barriers. Further, the proposed stochastic quantum-control scenario is demonstrated more generally as applied to an archetype model, a particle tunnelling in a quartic double-well potential.

Yanchao She, Xuejun Zheng, Denglong Wang +1 more

We consider the coupling effect between interdot tunneling coupling and external optical control field to study the linear optical property and the formation of temporal optical solitons in a quantum dot molecules system, analytically. The results show that the double tunneling induced transparency (TIT) windows are appeared in the absorption curve of probe field because of the formation of dynamic Stark splitting and quantum destructive interference effect from the two upper levels. Interestingly, the width of the TIT window becomes wider with the increasing intensity of the optical control field. We also find that the Kerr nonlinear effect of the probe field can be modulated effectively through coherent control both the control field and the interdot tunneling coupling in this system. Meanwhile, we demonstrate that the formation of dark or bright solitons can be practical regulated by varying the intensity of the optical control field.

Ángel S. Sanz, Salvador Miret-Artés

Yu-Ao Chen, Sylvain Nascimbène, Monika Aidelsburger +3 more

The dynamical control of tunneling processes of single particles plays a major role in science ranging from Shapiro steps in Josephson junctions to the control of chemical reactions via light in molecules. Here we show how such control can be extended to the regime of correlated tunneling of strongly interacting particles. Through a periodic modulation of a biased tunnel contact, we have been able to coherently control single-particle and correlated two-particle hopping processes. We have furthermore been able to extend this control to superexchange spin interactions in the presence of a magnetic-field gradient. Such photon-assisted superexchange processes constitute a novel approach to realize arbitrary XXZ spin models in ultracold quantum gases, where transverse and Ising-type spin couplings can be fully controlled in magnitude and sign.