Time Resolved Control of Electron Tunnelling Times and Single-shot Spin Readout in a Quantum Dot

We are pursuing a capability to perform time resolved manipulations of single spins in quantum dot circuits involving more than two quantum dots. In this paper, we demonstrate full counting statistics as well as averaging techniques we use to calibrate the tunnel barriers. We make use of this to implement the Delft protocol for single shot single spin readout in a device designed to form a triple quantum dot potential. We are able to tune the tunnelling times over around three orders of magnitude. We obtain a spin relaxation time of 300 microseconds at 10T.Comment: Submitted to EP2DS 2009 Conference Proceeding

A high speed radio-frequency quantum point contact charge detector for time resolved readout applications of spin qubits

In this paper,we give details related to the implementation of a rf-QPC charge detector coupled to a GaAs/AlGaAs triple dot. Each component of the readout circuit is discussed with emphasis on the isolator. We use a10 K noise temperature HEMT amplifier in the readout and determine that the attenuation of amplifier noise that the isolator provides is not significant. A base electron temperature of 100mK is reached independent of the existence of the isolator in the readout circuit. We also discuss the use of normal metal and superconducting resonant circuits. Using the superconducting resonant circuit, we detect charge motion in the device and determine that the bandwidth of the readout is at least 1 MHz with a sensitivity of 1:46 x10-4e/ 1aHz .Peer reviewed: YesNRC publication: Ye