Princeton Quantum Seminar
Pavel Kurilovich, Yale University
“High-frequency readout of a superconducting qubit: how non-demolishing can a quantum measurement be?”

Abstract: "Measurement of a quantum bit is an essential part of quantum error correction protocols. The ability to carry out these protocols requires the readout to be accurate and have a near-perfect quantum non-demolition character. In superconducting circuits, an attempt at achieving a quantum non-demolition measurement is provided by dispersive readout. In this approach, the information about the qubit state is extracted from the microwaves elastically scattered from the qubit. In transmons – the most commonly used superconducting qubits – the non-demolition fidelity of dispersive readout has so far been limited by the presence of undesired resonances between the computational and non-computational states. A high-power readout tone activates these resonances ruining the computation. The activation of the spurious resonances is unavoidable in the conventional regime where the readout frequency is of the same order as the transmon frequency.

Host: Professor Andrew Houck, ECE