Low Temperature Physics: 39, 503 (2013); https://doi.org/10.1063/1.4811251 (12 pages)
Физика Низких Температур: Том 39, Выпуск 6 (Июнь 2013), c. 649-662    ( к оглавлению , назад )

Electromagnetically induced interference in a superconducting flux qubit

Lingjie Du1,2, Yang Yu1, and Dong Lan1

1National Laboratory of Solid State Microstructures and Department of Physics Nanjing University, Nanjing 210093, China
E-mail: lingjie.du@rice.edu
yuyang@nju.edu.cn

2Department of Physics and Astronomy, Rice University, Houston, Texas 77251-1892, USA

Received November 23, 2012, revised December 22, 2012

Аннотация

Interaction between quantum two-level systems (qubits) and electromagnetic fields can provide additional coupling channels to qubit states. In particular, the interwell relaxation or Rabi oscillations, resulting, respectively, from the multi- or single-mode interaction, can produce effective crossovers, leading to electromagnetically induced interference in microwave driven qubits. The environment is modeled by a multimode 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 demon-strate the relaxation can generate population inversion in a strongly driving two-level system. On the other hand, different from Rabi oscillations, 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 qubits either with or without crossover structure.

PACS: 03.67.Lx Quantum computation architectures and implementations;
PACS: 32.80.Xx Level crossing and optical pumping;
PACS: 42.50.Hz Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift.

Ключевые слова: quantum qubits, Rabi-oscillation-induced interference.