Abstract:

In this talk, I will give a basic overview of radio-frequency reflectometry techniques to measure solid-state qubits. In particular, I will discuss fast charge state readout in carbon nanotube double quantum dots. Using low-temperature strontium titanate varactors for impedance matching, we optimize signal-to-noise ratios and obtain record charge and capacitance sensitivities. We show that high-fidelity charge and spin state readout on the order of 100 ns is feasible, i.e. on much shorter timescales as compared to typical spin lifetimes. I will furthermore discuss microwave spectroscopy (Landau-Zener-Stuckelberg interferometry) and charge noise characterisation of the carbon nanotube double quantum dot devices. 

Bio:

Mark Buitelaar is an Associate Professor at the London Centre for Nanotechnology and Department of Physics & Astronomy at University College London (UCL), UK. He received his PhD from the University of Basel, CH, and has previously held research posts at the University of Cambridge, UK, including a Royal Society Dorothy Hodgkin Fellowship. His research interests focus on engineering quantum coherence and correlations in nanoscale quantum devices. He has pioneered work on superconducting and Kondo correlations in quantum dots, Pauli spin blockade and radio-frequency reflectometry readout of quantum devices. His latest work involves the development of cryogenic quantum paraelectric varactors, providing record capacitance sensitivity and ultrafast and high-fidelity readout of solid-state quantum devices.