Dynamics of sequential quantum tunneling

Neil Turok

Wenjie Hou, Yuandong Wang, Jianhua Wei +2 more

Abstract Quantum tunneling dominates coherent transport at low temperatures in many systems of great interest. In this work we report a many–body tunneling (MBT), by nonperturbatively solving the Anderson multi-impurity model, and identify it a fundamental tunneling process on top of the well–acknowledged sequential tunneling and cotunneling. We show that the MBT involves the dynamics of doublons in strongly correlated systems. Proportional to the numbers of dynamical doublons, the MBT can dominate the off–resonant transport in the strongly correlated regime. A T3/2–dependence of the MBT current on temperature is uncovered and can be identified as a fingerprint of the MBT in experiments. We also prove that the MBT can support the coherent long–range tunneling of doublons, which is well consistent with recent experiments on ultracold atoms. As a fundamental physical process, the MBT is expected to play important roles in general quantum systems.

Zvi Kotler, Abraham Nitzan, Ronnie Kosloff

Jakub Łuczak, Bogdan R. Bułka

We study the short time dynamics of a charge qubit encoded in two coherently coupled quantum dots connected to external electrodes.In the regime of sequential tunneling the waiting time distribution is used to investigate in details statistics of the tunneling events and their correlations.We show that the coherent rotation of the qubit state on the Bloch sphere can be seen in tunneling events when an electron is injected and leave the system.Decoherence, relaxation of the qubit state as well as leakage processes are studied by means of transient currents.

Richard Giovanni Avella, Ramón Rafael Rey González, K. M. Fonseca-Romero

The sequential to correlated-tunneling transition of two identical bosons confined in a symmetrical double well potential is studied using a time-dependent variational formalism. Increasing the strength of the short-range boson-boson interaction, the probability of finding both bosons in the same well allow to identify three regimes. For small values of the boson- boson coupling constante, this probability display beatings. Then, the probability of finding both bosons in the same well becomes quasi-periodical in time, for almost all values of the coupling constant; however, there is a zero-measure set, which contains an infinity of points, for which this probability is time-periodic. Finally, for larger values of the coupling constant, this probability changes periodically. Based on the dynamics of the probability of finding one boson on each well and increasing the boson-boson interaction, we find that tunnelling changes from a regime where one boson tunnels after the other to a regime in which they tunnel together.

Antonio Defendi, Marco Roncadelli