Dissipative coherent tunneling

H. Dekker

Xiao-Xiao Zhang, Naoto Nagaosa

We study in the presence of dissipation the quantum phenomena of tunneling and especially interference around a Weyl-like or conical potential crossing due to the monopolar Berry gauge phase. It is pertinent to a wide range of physical and quantum chemical phenomena, and we microscopically motivate this model from the effective dynamics of collective degrees of freedom arising from a two-level system coupled to a bosonic bath. Using the instanton approach with symmetry analysis and advanced numerical methods, we are able to investigate the interplay between phase interference and dissipation by resolving the phase diagram of coherent tunneling with respect to the potential bias and dissipation. Under emergent mirror symmetry protection, the coherent tunneling exhibits Kramers degeneracy, nonmonotonic dependence on dissipation and a generic phase transition to no interference, before which an anomalous dissipation-enhanced regime persists.

Zhen Bao

A. O. Caldeira

Xiao-Xiao Zhang, Naoto Nagaosa

The Berry phase effect plays a central role in many mesoscale condensed matter and quantum chemical systems that are naturally under the environmental influence of dissipation. We propose and microscopically derive a prototypical quantum coherent tunneling model around a monopole or conical potential intersection in order to address the intriguing but overlooked interplay between dissipation and the topologically nontrivial Berry phase effect. We adopt the instanton approach with both symmetry analysis and accurate numerical solutions that consistently incorporate nonperturbative dissipation and the Berry phase. It reveals a unique and interesting dissipative quantum interference phenomenon with the Berry phase effect. The phase diagram of this tunneling exhibits Kramers degeneracy, nonmonotonic dependence on dissipation, and a generic dissipation-driven phase transition of quantum interference, before which an unconventional dissipation-enhanced regime of quantum tunneling persists.