Singlet-triplet readout in Si quantum dots based on (2,1)-charge state

Dr Tuomo Tanttu
4pm Thursday 20 July 2017
CQC2T Conference Room, Level 2, Newton Building J12, UNSW Kensington Campus

Singlet-triplet readout of two nearest neighbor quantum dots is an essential tool for scaling up quantum computing in silicon MOS systems [1]. Traditionally this parity readout is done in (2,0) charge configuration of a double quantum dot systems where triplet states are blockaded in (1,1) state due to Pauli exclusion principle. This difference in the charge configuration can be detected with a charge sensor only if the two dots have sufficient differential capacitance to the sensor. We review recent studies where the readout visibility is increased largely by using either (2,1) or (1,0) charge state [2,3] and discuss the conditions required for such "latching" readout. Furthermore we present recent experimental results of our silicon quantum dot array that show we can employ latching readout to enhance the readout visibility in our system. We conclude that the visibility of our singlet-triplet readout is increased to 98%

[1] C. Jones et al. arXiv:1608.06335 (2016)
[2] P. Harvey-Collard et al. arXiv:1703.02651 (2017)
[3] T. Nakajima et al. Phys. Rev. Lett. 119, 017701 (2017)