Quantum control of driven artificial atoms

A. FERRÓN, D. DOMINGUEZ AND M. J. SÁNCHEZ

, Mar del Plata

Conferencia; Quantum Optics VII; 2014

p { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); text-align: left; }p.western { font-family: "Times New Roman",serif; font-size: 12pt; }p.cjk { font-family: "DejaVu Sans"; font-size: 12pt; }p.ctl { font-family: "DejaVu Sans"; font-size: 12pt; } Quantum control of driven artificial atoms In laser physics the usual mechanism to get Population inversion (PI) requires three or more atomic levels.Interesting systems to study PI are `artificial atoms´ made with mesoscopic Josephson devices. Among them, is the flux qubit (FQ), which for millikelvin temperatures exhibits quantized energy levels that are sensitive to an external magnetic field.When the FQ is driven with an ac field, it can be excited to the third and fourth energy levels through Landau-Zener transitions. The interaction with the environmental bath provides the usual mechanisms for relaxation and decoherence, which are necessary to induced PI.In this talk I will show that more notable effect can developed in these systems if the ac driving pulses are applied for longer time scales : PI could be observed solely mediated by the environmental bath, i.e. for ac amplitudes where only the two lowest levels of the FQ participate. Furthermore, the degree of population inversion could be controlled by tailoring a resonant frequency W in the environmental bath. In this talk it will be described: (i) how this bath mediated type of PI can be obtained and (ii) how the occurrence and the degree of PI can be tailored by changing the structure of the environmental bath. References: Tailoring population inversion in Landau-Zener-Stuckelberg interferometry of flux qubits,A. Ferrón, D. Dominguez and M. J. Sánchez, Pys. Rev. Lett. 109, 237005 (2012). Mesoscopic fluctuations in artificial atoms driven by biharmonic signals. A. Ferrón, D. Dominguez and M. J. Sánchez,submitted (2014).