Feedback Control of Superconducting Quantum Circuits

2 06/2014

Monday, 02 Jun. 2014, 17:30 - 19:00

Presenter: Prof. Leonardo DiCarlo
Host: Philip Walther
Where: ATI, Lecture Hall, Stadionallee 2, 1020 Wien

Advances in low-noise amplification at microwave frequencies and in qubit coherence have transformed superconducting circuits into a versatile testbed for quantum measurement, driven by interest in the measurement problem and next milestones in quantum error correction.   I present the development of non-demolition multi-qubit measurements for transmon qubits in circuit quantum electrodynamics, and the implementation of real-time feedback using their results. We aim to realize modern quantum error correction schemes, such as the surface code, in which parity measurements discretize errors, and digital feedback corrects them.  Initial results on this path include fast qubit reset, two-qubit entanglement by measurement, and active cancellation of measurement-induced dephasing. Current efforts facing scalability focus on multiplexed closed-loop control in a five-qubit, seven-resonator processor targeting a simple repetition code.