Towards the stabilization of one photon Fock state in a superconducting resonator

Gianluca Aiello, Mathieu Fechant, Alexis Morvan, Jérôme Esteve, and Julien Gabelli
Laboratoire de physique des solides, CNRS, Université Paris-Saclay, 91405 Orsay CEDEX, France

In a recent proposal Souquet and Clerk [1], showed how it is possible to stabilize a Fock State in superconducting quantum circuits through the biasing of a single Josephson junction.
This protocol involves the use of high impedance (Z) cavities in order to achieve the strong coupling regime between the junction and resonators which is reached when Z = h/2 π e24 kΩ. This is normally done using arrays of SQUIDs as shown in [2]. Here we present a different approach, that involves the use of disorder material (NbSi) whose high kinetic inductance allows to design and fabricate cavities with high impedance. Preliminary results show that we are already able to obtain, using a 2 μm wide NbSi wire (see figure 1), a 4 kΩ  impedance resonator with a quality factor, limited by the coupling, close to 160.

aiello
Figure 1: Picture of the sample and schematics of the circuit (left). Transmission spectrum of the resonant cavity (right)

References
[1] Souquet, J. R. and Clerk, A. A. Fock-state stabilization and emission in superconducting circuits using dc-biased Josephson junctions. Physical Review A 93, 6 (2016)
[2] Altimiras C. et al. Tunable microwave impedance matching to a high impedance source using a Josephson metamaterial. Applied Physics Letter 103, 212601 (2013)

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