Applied Physics Seminar - Mostafa Khezri - UC Riverside

Event time: 
Friday, February 2, 2018 - 1:00pm to 2:00pm
YQI Seminar Room - 4th Floor See map
17 hillhouse Avenue
Event description: 

Measurement of superconducting qubits

Superconducting qubits are among the most promising candidates for building a quantum computer. In this talk, we discuss high power measurement of their current popular flavor, the transmon qubit. For measurement, the qubit is dispersively coupled to a detuned readout resonator; this forms a Jaynes-Cummings (JC) ladder of energies between the two. In this talk we explore this JC ladder to study the measurement at large powers, and to explain the experimental observations which were performed on tunable transmon qubits. In particular, we introduce dressed squeezed state as an approximation of the joint state of the qubit and its readout resonator, and show that (usually neglected) non-RWA couplings lead to abrupt qubit state deterioration with increasing measurement microwave power.