Dressed State Dissipation - Modeling Dissipation in a Strongly Driven Qubit

When matter and light interact at the quantum level, in the form of atoms and photons, it is often no longer possible to clearly distinguish their individual contributions to the overall behavior of the system. This mixing of their distinct aspects can then be described in terms of dressed states.

Dressed states have long been an essential concept in many fields of physics and have recently been invoked to explain the behavior of electrical circuits operating in the quantum regime. In this context, known as circuit quantum electrodynamics (QED), we directly measure a class of states, longitudinal dressed states (LDS), that have received little experimental attention in the past.

We create these states by illuminating an artificial atom made from a nanofabricated superconducting circuit with microwave photons. We then observe the interaction of the dressed states and a radio-frequency oscillator. This measurement scheme allows us to directly map the dressed energy diagram and extract the relaxation and dephasing times of the states. LDS are the natural description of a strongly driven superconducting quantum bit (qubit) and may have applications in the field of quantum information processing.

Work done in collaboration between the Quantum Device Physics Laboratory and the Applied Quantum Physics Laboratory at MC2.

For more information see C. M. Wilson, T. Duty, F. Persson, M. Sandberg, G. Johansson, and P. Delsing, Phys. Rev. Lett. 98, 257003 (2007)