Quantum coherence and population transfer in a driven cascade three-level artificial atom

Abstract

We present an experimental investigation on the spectral characteristics of an artificial atom "transmon qubit" constituting a three-level cascade system (Ξ-system) in the presence of a pair of external driving fields. We observe two different types of Autler-Townes (AT) splitting: type I, where the phenomenon of two-photon resonance tends to diminish as the coupling field strength increases, and type II, where this phenomenon mostly stays constant. We find that the types are determined by the cooperative effect of the decay rates and the field strengths. Theoretically analyzing the density-matrix elements in the weak-field limit where the AT effect is suppressed, we single out events of pure two-photon coherence occurring owing to constructive quantum interference.

accepted for publication in PRA

References in corpus (5)

• Charge insensitive qubit design derived from the Cooper pair box
• Electromagnetically induced transparency with single atoms in a cavity
• Nonlinear response of the vacuum Rabi resonance
• Measurement of Autler-Townes and Mollow transitions in a strongly driven superconducting qubit
• Control and Tomography of a Three Level Superconducting Artificial Atom