Controllable cross-Kerr interaction between microwave photons in circuit quantum electrodynamics**Project supported by the National Natural Science Foundation of China (Grant Nos. 10775048 and 11075050), the National Basic Research Program of China (Grant No. 2007CB925204), and the Education Department of Hunan Province, China (Grant No. 08W012).

Abstract

We propose a scheme to enable a controllable cross-Kerr interaction between microwave photons in a circuit quantum electrodynamics (QED) system. In this scheme we use two transmission-line resonators (TLRs) and one superconducting quantum interference device (SQUID) type charge qubit, which acts as an artificial atom. It is shown that in the dispersive regime of the circuit-QED system, a controllable cross-Kerr interaction can be obtained by properly preparing the initial state of the qubit, and a large cross-phase shift between two microwave fields in the two TLRs can then be reached. Based on this cross-Kerr interaction, we show how to create a macroscopic entangled state between the two TLRs.