| 报告题目 | Dissipation in Quantum tunneling: A Platform for Quantum Phase Transitions and A Majorana Signature Filter |
| 报告人 | Dr. LIU Dong |
| 报告人单位 | Department of Physics and Astronomy, Michigan State University |
| 报告时间 | 2014-05-28 |
| 报告地点 | 合肥微尺度物质科学国家实验室九楼会议室 |
| 主办单位 | 合肥微尺度物质科学国家实验室 |
| 报告介绍 | 报告摘要：
When a tunnel barrier is in contact with resistive leads, the electromagnetic excitations in the leads provide a bosonic bath. In Nano-electronic circuits, the quantum fluctuations couple to such a bath and induce quantum dissipation effects. We first study tunneling through a resonant level connected to dissipative baths. We show that several quantum phase transitions (QPT) occur in such a model, transitions which emulate those found in interacting systems such as Luttinger liquids. For strong dissipation, a BKT QPT separates strong-coupling and weak-coupling phases. In the source-drain symmetric case, all relevant backscattering processes disappear at strong coupling, leading to perfect transmission at zero temperature. We also find a second order QPT occurs as a function of the coupling asymmetry or energy of the resonant level. Inspired by the result above, I secondly consider the dissipative tunneling (by using resistive electrodes) into a Majorana fermion (FM) zero mode. I find that the ways that the dissipation effects renormalize the tunneling conductance is significantly different for MFs and other cases: 1) The Majorana zero-bias peak still increase as temperature decreases; 2) the peak due to other effects splits into two at finite temperature and the conductance at zero voltage bias shows a power law suppression as a function of temperature.
In the last 15 minutes of the talk, I will briefly discuss the possibility of constructing the topological qubits based on certain non-equilibrium stationary states, i.e. Floquet states. I will talk about the recent progresses and some open problems on this topic. |
