1201.6341 (Simon Gustavsson et al.)

Driven dynamics and rotary echo of a qubit tunably coupled to a harmonic
oscillator    [PDF]

Simon Gustavsson, Jonas Bylander, Fei Yan, Pol Forn-Díaz, Vlad Bolkhovsky, Danielle Braje, George Fitch, Khalil Harrabi, Donna Lennon, Jovi Miloshi, Peter Murphy, Rick Slattery, Steven Spector, Ben Turek, Terry Weir, Paul B. Welander, Fumiki Yoshihara, David G. Cory, Yasunobu Nakamura, Terry P. Orlando, William D. Oliver

We have investigated the driven dynamics of a superconducting flux qubit that
is tunably coupled to a microwave resonator. We find that the qubit experiences
an oscillating field mediated by off-resonant driving of the resonator, leading
to strong modifications of the qubit Rabi frequency. This opens an additional
noise channel, and we find that low-frequency noise in the coupling parameter
causes a reduction of the coherence time during driven evolution. The noise can
be mitigated with the rotary-echo pulse sequence, which, for driven systems, is
analogous to the Hahn-echo sequence.

View original: http://arxiv.org/abs/1201.6341