Advances in quantum control of three-level superconducting circuit architectures

  1. G. Falci,
  2. P. G. Di Stefano,
  3. A. Ridolfo,
  4. A. D'Arrigo,
  5. G. S. Paraoanu,
  6. and E. Paladino
Advanced control in Lambda (Λ) scheme of a solid state architecture of artificial atoms and quantized modes would allow the translation to the solid-state realm of a whole class of
phenomena from quantum optics, thus exploiting new physics emerging in larger integrated quantum networks and for stronger couplings. However control solid-state devices has constraints coming from selection rules, due to symmetries which on the other hand yield protection from decoherence, and from design issues, for instance that coupling to microwave cavities is not directly switchable. We present two new schemes for the Λ-STIRAP control problem with the constraint of one or two classical driving fields being always-on. We show how these protocols are converted to apply to circuit-QED architectures. We finally illustrate an application to coherent spectroscopy of the so called ultrastrong atom-cavity coupling regime.

Non-equilibrium thermodynamics of continuously measured quantum systems: a circuit-QED implementation

  1. P. G. Di Stefano,
  2. J. J. Alonso,
  3. E. Lutz,
  4. G. Falci,
  5. and M. Paternostro
We propose a fully operational framework to study the non-equilibrium thermodynamics of a quantum system S that is coupled to a detector D whose state is continuously monitored, allowing
to single out individual quantum trajectories of S. We focus on detailed fluctuation theorems and characterize the entropy production of the system. We establish fundamental differences with respect to the thermodynamic of unmonitored, unitarily evolved systems. We consider the paradigmatic example of circuit-QED, where superconducting qubits can be coupled to a continuously monitored resonator and show numerical simulations using state of the art experimental parameters.

Coherent manipulation of noise-protected superconducting artificial atoms in the Lambda scheme

  1. P. G. Di Stefano,
  2. E. Pladino,
  3. T. J. Pope,
  4. and G. Falci
We propose a new protocol for thr manipulation of a three-level artificial atom in Lambda (Λ) configuration in the absence of a direct pump coupling. It allows faithful, selective
and robust population transfer analogous to stimulated Raman adiabatic passage (Λ-STIRAP), in highly noise protected superconducting artificial atoms. It combines the use of a two-photon pump pulse with suitable advanced control, operated by a slow modulation of the phase of the external fields, leveraging on the stability of semiclassical microwave drives. This protocol is a building block for novel tasks in complex quantum architectures. Its demonstration would be a benchmark for the implementation of a class of multilevel advanced control procedures for quantum computation and microwave quantum photonics in systems based on artificial atoms.