Single-Shot Readout of Electron Spins in a Semiconductor Quantum Dot

摘要

We demonstrate single-shot readout of spin states in a semiconductor quantum dot. The readout process consists of spin-to-charge conversion via spin-dependent tunneling of an electron off the dot, combined with a fast (approx 40 kHz bandwidth) measurement of the resulting charge dynamics, using a nearby quantum point contact as an electrometer. Spin-dependent tunneling can be induced by either using the difference in energy or using the difference in tunnel rate between the spin states, allowing readout over a wide range of magnetic fields. We find very long relaxation times (up to milliseconds), both for relaxation between single-electron Zeeman levels and for relaxation between two-electron triplet and singlet states.