CPM Seminar

Hyperfine-coupling-programming of current through coupled vertical quantum dots with multiple-sweep bias voltage waveforms (“nuclear spin flash memory”)

Guy Austing

National Research Council
Ottawa

Current switching and hysteresis due to electron spin-nuclear spin (hyperfine) coupling have over the past 5 years been observed in the two-electron spin-blockade regime of coupled quantum dots. Hyperfine coupling has played a key role in recent demonstrations of basic qubit operations, and quantum memory with nuclear spins has also been has been proposed. Recently, a novel scheme for nuclear spin pumping with subsequent readout was demonstrated by Baugh et al at Tokyo University. After introducing why nuclear spin is an important consideration in III-V quantum dot structures and how the nuclear spin may be polarized, I will describe our recent work on the application of complex multiple-sweep bias voltage waveforms to program unique features into the tunneling current through a vertical double dot structure which are memorized on a time scale of a few tens of seconds. There are many outstanding questions related to the hyperfine interaction, particularly on the long timescale (> 1 sec). Nonetheless, measurement protocols utilizing hyperfine related effects can be explored for basic memory and even logic operations.

Research done with Chris Payette, Guolin Yu and James Gupta