Dynamic transition and quantum bath engineering in driven superconducting flux qubits

Date: 4 May 2017

Venue: UAntwerpen, Campus Groenenborger, Building U, room U.241 - Groeneborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Condensed Matter Theory Seminar presented by Prof Daniel Dominguez from Centro Atomico Bariloche

In recent years, the experimental realization of LandauZener-Stuckelberg (LZS) interferometry  in several systems has emerged as a tool to study quantum coherence under
strong driving. In two-level systems driven by an ac force, the accumulated phase between periodically repeated LZS tunneling events at avoided crossings gives place to constructive or destructive interferences, depending on the driving amplitude and the detuning from avoided crossing.    

I will discussLZS interferometry in superconducting flux qubits coupled to an Ohmic quantum bath. We have found a dynamic transition manifested by a symmetry change in the structure of the LZS interference pattern, plotted as a function of ac amplitude and dc detuning. The dynamic transition is from an LZS pattern with nearly symmetric multiphoton resonances to antisymmetric multiphoton resonances at long times (above the relaxation time). I will also discuss the effect of the quantum bath spectral structure and the system-bath coupling on the LZS interference pattern and compare with experiments in flux qubits.

Contact email: lucian.covaci@uantwerpen.be

Link: http://cmt.uantwerpen.be