O. Astafiev

Landau-Zener-Stückelberg-Majorana lasing in circuit QED

  1. P. Neilinger,
  2. S. N. Shevchenko,
  3. J. Bogár,
  4. M. Rehák,
  5. G. Oelsner,
  6. D. S. Karpov,
  7. O. Astafiev,
  8. M. Grajcar,
  9. and E. Il'ichev
We demonstrate amplification (and attenuation) of a probe signal by a driven two-level quantum system in the Landau-Zener regime. In the experiment, a superconducting qubit was strongly
coupled to a microwave cavity, the conventional arrangement of circuit quantum electrodynamics. Two different types of flux qubits show a similar result, lasing at the points where amplification takes place. The experimental data are explained by the interaction of the probe signal with Rabi-like oscillations. The latter are created by constructive interference of Landau-Zener-St\“{u}ckelberg-Majorana (LZSM) transitions during the driving period of the qubit. A detailed description of the occurrence of these oscillations and a comparison of obtained data with both analytic and numerical calculations are given.
arxiv pdf

Correlated emission lasing in harmonic oscillators coupled via a single three-level artificial atom

  1. Z.H. Peng,
  2. Yu-xi Liu,
  3. J.T. Peltonen,
  4. T. Yamamoto,
  5. J. S. Tsai,
  6. and O. Astafiev
A single superconducting artificial atom provides a unique basis for coupling electromagnetic fields and photons hardly achieved with a natural atom. Bringing a pair of harmonic oscillators
into resonance with transitions of the three-level atom converts atomic spontaneous processes into correlated emission dynamics. We demonstrate two-mode correlated emission lasing on harmonic oscillators coupled via the fully controllable three-level artificial atom. Correlation of two different color emissions reveals itself as equally narrowed linewiths and quench of their mutual phase-diffusion. The mutual linewidth is more than four orders of magnitude narrower than the Schawlow-Townes limit. The interference between the different color lasing fields demonstrates the two-mode fields are strongly correlated.
arxiv pdf