arXiv:1610.09153 · Physical review. B./Physical review. B

Observation of the Bloch-Siegert shift in a driven quantum-to-classical transition

Iivari Pietikäinen, Sergey Danilin, K. S. Kumar, Antti P. Vepsäläinen, Dmitry S. Golubev, Jani Tuorila, Gheorghe Sorin Paraoanu

Published Jul 7, 2017• 51 citations

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Abstract

We show that the counter-rotating terms of the dispersive qubit-cavity Rabi model can produce relatively large and nonmonotonic Bloch-Siegert shifts in the cavity frequency as the system is driven through a quantum-to-classical transition. Using a weak microwave probe tone, we demonstrate experimentally this effect by monitoring the resonance frequency of a microwave cavity coupled to a transmon and driven by a microwave field with varying power. In the weakly driven regime (quantum phase), the Bloch-Siegert shift appears as a small constant frequency shift, while for a strong drive (classical phase) it presents an oscillatory behavior as a function of the number of photons in the cavity. The experimental results are in agreement with numerical simulations based on the quasienergy spectrum.

DOI: 10.1103/physrevb.96.020501

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