Tenghui Wang

Simulating a Topological Transition in a Superconducting Phase Qubit by Fast Adiabatic Trajectories

  1. Tenghui Wang,
  2. Zhenxing Zhang,
  3. Liang Xiang,
  4. Zhihao Gong,
  5. Jianlan Wu,
  6. and Yi Yin
The significance of topological phases has been widely recognized in the community of condensed matter physics. The well controllable quantum systems provide an artificial platform
to probe and engineer various topological phases. The adiabatic trajectory of a quantum state describes the change of the bulk Bloch eigenstates with the momentum, and this adiabatic simulation method is however practically limited due to quantum dissipation. Here we apply the `shortcut to adiabaticity‘ (STA) protocol to realize fast adiabatic evolutions in the system of a superconducting phase qubit. The resulting fast adiabatic trajectories illustrate the change of the bulk Bloch eigenstates in the Su-Schrieffer-Heeger (SSH) model. A sharp transition is experimentally determined for the topological invariant of a winding number. Our experiment helps identify the topological Chern number of a two-dimensional toy model, suggesting the applicability of the fast adiabatic simulation method for topological systems.
arxiv pdf

Measuring the Berry Phase in a Superconducting Phase Qubit by a Shortcut to Adiabaticity

  1. Zhenxing Zhang,
  2. Tenghui Wang,
  3. Liang Xiang,
  4. Jiadong Yao,
  5. Jianlan Wu,
  6. and Yi Yin
With a counter-diabatic field supplemented to the reference control field, the `shortcut to adiabaticiy‘ (STA) protocol is implemented in a superconducting phase qubit. The Berry
phase measured in a short time scale is in good agreement with the theoretical result acquired from an adiabatic loop. The trajectory of a qubit vector is extracted, verifying the Berry phase alternatively by the integrated solid angle. The classical noise is introduced to the amplitude or phase of the total control field. In the statistics of the Berry phase, the mean with either noise is almost equal to that without noise, while the variation with the amplitude noise can be described by an analytical expression.
arxiv pdf