DiCarlo, Leo

Friday Oct 11, 2013
Time: 13:45
Place: ETH Science City, HPF G 6
Host: Andreas Wallraff

Generating two-qubit entanglement by parity measurement and feedback in circuit QED

Leo DiCarlo
Kavli Institute of Nanoscience
Delft University of Technology

The development of a fault-tolerant quantum computer can be divided into seven phases. Superconducting quantum circuits have entered the third phase, known as the Age of Measurement, where quantum measurement takes center stage.  Wavefunction collapse by measurement is used to discretize errors in small-scale quantum processors, and feedback control is used to correct them. I present Delft developments in non-demolition measurement of superconducting qubits in the circuit quantum electrodynamics architecture, and initial applications in measurement-based feedback control.  Owing to their prevalence in modern quantum error correction, we focus on joint qubit readouts in the form of parity meters, and two experimental realizations using ancillary qubits and coupled resonators.  First applications include the probabilistic generation of two-qubit entanglement, and deterministic generation through digital feedback control. I also present the use of analog feedback control to combat unwanted quantum measurement backaction in the form of measurement-induced qubit dephasing.  We conclude with an outlook of exciting challenges in quantum engineering awaiting superconducting circuits.