Giant Kerr nonlinearities in Circuit-QED

TL;DR

This paper demonstrates how a single artificial multi-level system in circuit-QED can produce giant Kerr nonlinearities at microwave frequencies, enabling new quantum optics experiments without absorption losses.

Contribution

It introduces a method to generate large optical nonlinearities using a single superconducting artificial atom, overcoming challenges of multi-atom systems.

Findings

Giant self-Kerr effect observed via correlation measurements

No associated absorption with the nonlinearities

Potential for exploring novel quantum physics in circuit-QED

Abstract

The very small size of optical nonlinearities places wide ranging restrictions on the types of novel physics one can explore. For an ensemble of multi-level systems one can synthesize a large effective optical nonlinearity using quantum coherence effects but such non-linearities are technically extremely challenging to demonstrate at the single atom level. In this work we describe how a single artificial multi-level Cooper Pair Box molecule, interacting with a superconducting microwave coplanar waveguide resonator, when suitably driven, can generate extremely large optical nonlinearities at microwave frequencies, with no associated absorption. We describe how the giant self-Kerr effect can be detected by measuring the second-order correlation function and quadrature squeezing spectrum.