Ultrafast quantum gates in circuit QED

Phys Rev Lett. 2012 Mar 23;108(12):120501. doi: 10.1103/PhysRevLett.108.120501. Epub 2012 Mar 19.

Abstract

We present a method to implement ultrafast two-qubit gates valid for the ultrastrong coupling and deep strong coupling regimes of light-matter interaction, considering state-of-the-art circuit quantum electrodynamics technology. Our proposal includes a suitable qubit architecture and is based on a four-step sequential displacement of the intracavity field, operating at a time proportional to the inverse of the resonator frequency. Through ab initio calculations, we show that these quantum gates can be performed at subnanosecond time scales while keeping a fidelity above 99%.