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arXiv · 1610.09153

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

I. Pietikäinen·S. Danilin·K. S. Kumar·A. Vepsäläinen·D. S. Golubev·J. Tuorila·G. S. Paraoanu
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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 strong drive (classical phase) it presents an oscillatory behaviour 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.

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I. Pietikäinen, S. Danilin, K. S. Kumar, A. Vepsäläinen, D. S. Golubev, J. Tuorila, G. S. Paraoanu. 2016-10-28. Observation of the Bloch-Siegert shift in a driven quantum-to-classical transition. https://doi.org/10.1103/physrevb.96.020501

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