Electromagnetically induced interference at superconducting qubits

TL;DR

This paper investigates electromagnetically induced interference in superconducting qubits, revealing how environmental interactions and Rabi oscillations influence qubit dynamics and offering new methods for quantum control and characterization.

Contribution

It introduces a detailed analysis of relaxation and Rabi oscillation induced interference, providing insights into qubit-environment interactions and novel control techniques.

Findings

Relaxation induces interference independent of tunnel coupling.

Relaxation can generate population inversion in strongly driven systems.

Rabi oscillation induced interference offers controllable qubit manipulation.

Abstract

We study electromagnetically induced interference at superconducting qubits. The interaction between qubits and electromagnetic fields can provide additional coupling channels to qubit states, leading to quantum interference in a microwave driven qubit. In particular, the interwell relaxation or Rabi oscillation, resulting respectively from the multi- or single-mode interaction, can induce effective crossovers. The environment is modeled by a multi-mode thermal bath, generating the interwell relaxation. Relaxation induced interference, independent of the tunnel coupling, provides deeper understanding to the interaction between the qubits and their environment. It also supplies a useful tool to characterize the relaxation strength as well as the characteristic frequency of the bath. In addition, we demonstrate the relaxation can generate population inversion in a strongly driving two-level system. On the other hand, different from Rabi oscillation, Rabi oscillation induced interference involves more complicated and modulated photon exchange thus offers an alternative means to manipulate the qubit, with more controllable parameters including the strength and position of the tunnel coupling. It also provides a testing ground for exploring nonlinear quantum phenomena and quantum state manipulation, in not only the flux qubit but also the systems with no crossover structure, e.g. phase qubits.