Introduction of a DC Bias into a High-Q Microwave Cavity*

The circuit quantum electrodynamics (QED) architecture has been demonstrated to allow study cavity QED physics in a high-Q on- chip microwave cavity[1]. Here we develop a technique to apply a DC current or voltage bias to nanostructures embedded in the microwave cavity without significantly disturbing the cavity modes or degrading the Q at high frequencies. The DC biasing scheme will be discussed. Experimental results show good agreement with theoretical predictions. New highly non- linear fully quantum mechanical devices can be developed by embedding Josephson junction devices such as Superconducting Quantum Interference Devices (SQUIDs) or single electron transistors (SETs) in the high-Q microwave cavity. Furthermore, by integrating a nanomechanical resonator, such cavities may also be used to investigate the quantum to classical transition. [1] A. Wallraff et al, Nature, 431, 162 (2004).