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Abstract |
In nature the emission of photon from electronic relaxation is a well known phenomenon. The rate at which this process happens is controlled by the fine structure constant alpha=1/137. Because of this small value, the emission of more than one photon from a single relaxation event is a very rare event in nature and in optical experiments. In order to increase the probability of emission of photon multiplets it is necessary to increase the light-matter coupling intensity which can be done in the context of circuit QED by properly designing an RF resonator. I will discuss here the result obtained on a device with a coupling factor alpha = 2 [1]. By biasing a SQUID in series with a microwave resonator with a strong inductance coil we observe the emission of k photons for dc voltages Vdc=khf/2e which allows us to witness the emission of photon multiplets up to k=6. In order to investigate the statistic of the emission we compute the Fano factor from measurements of a second order correlator and find that for small enough Josephson energies the Fano factor coincides with k. We also perform a theoretical analysis of our system in order to understand the role of the bias noise as well as the detuning from the resonance condition and find a good agreement between theory and experiment.
[1] C. Rolland et al. Phys. Rev. Lett. 122, 186804 (2019) |
