Interview for Faculty Position

Quantum dynamics and nanoscale nuclear magnetism

William Coish

University of Waterloo

The study of coherent quantum dynamics in nanoscale condensed-matter systems has emerged as an essential tool for applications in quantum information processing, precision measurement, biomedical sensing, photovoltaic effects, and even bird migration. The charge (orbital) degree of freedom of electrons in solids is susceptible to strong decoherence because of the Coulomb interaction, and is therefore typically a poor carrier of quantum coherence. In contrast, electron and nuclear spins or photons have a relatively much weaker coupling to their environments, giving rise to long-lived coherent quantum dynamics, with significant consequences.

In this talk I will discuss three problems where complex coherent quantum dynamics plays a role: (1) The theory of the preparation and preservation of special 'narrowed' nuclear-spin states in a nanoscale semiconductor quantum dot and the resulting many-body coherent dynamics of a single electron spin in a nuclear-spin environment, (2) The creation of highly-entangled photon pairs from the recombination of a biexciton, and (3) The current and dynamical fluctuations (frequency-dependent shot-noise) for electrons passing through a double quantum dot in the Pauli spin blockade regime, where spin coherence determines transport characteristics. In each of these cases, I will show how very recent theoretical work has opened new doors to understanding the above applications, and how theory and experiment have supported each other along the way.