Download Quantum dots and radio-frequency electrometers in silicon

Quantum dots and radio-frequency electrometers in silicon
Dr Andrew Ferguson
Cavendish Laboratory, University of Cambridge
An important goal for solid-state quantum computing is to confine a single electron in silicon,
then manipulate and subsequently determine its spin state. Silicon has a low nuclear spin density
which, together with the low spin-orbit coupling in this material, is expected yield very long spin
relaxation times.
I will present recent results on silicon quantum dots with tuneable tunnel barriers. Lowtemperature electrical transport measurements are performed in both the many electron (N~100)
and the few electron (N~10) regimes.
In the second part of this talk, I will discuss the same device geometry but now configured as a
radio-frequency electrometer. With the quantum dot embedded in a resonant tank circuit charge,
charge sensitivities of dq<10-5 eHz-0.5 are demonstrated with MHz bandwidth. This
performance is comparable to aluminium radio-frequency single electron transistors.
Future aims are to perform charge sensing measurements on the quantum dot with the radiofrequency electrometer, and to engineer the quantum dot towards the single electron level. In
addition, I will discuss the potential of the radio-frequency electrometer to measure single dopant
atoms in silicon.