Alexandre Blais, University of Sherbrooke
Abstract
Coupling of superconducting qubits to quantized microwave fields stored in electrical circuits has opened new possibilities for quantum optics and quantum information processing in solid-state devices. With the steady improvements of the coherence time of superconducting qubits, and with the large qubit-field coupling that can be achieved, these on-chip realizations of cavity QED, also known as circuit QED, can reach new parameter regimes currently unexplored in traditional quantum optics. After a short introduction to circuit QED, I will propose a new approach, based on modulations of the qubit frequency, to realize two-qubit gates in circuit QED. I will also argue that the very same mechanism, when induced by environmental noise, can also lead to unwanted transitions in the qubit state and that this can be used as a new probe of dephasing noise at high frequencies. First experimental confirmations of these ideas will be presented.