Characterisation of a scalable donor based singlet-triplet qubit architecture

Mr Prasanna Pakkiam
4pm Thursday 30 November 2017
CQC2T Conference Room, Level 2, Newton Building J12, UNSW Kensington Campus

We present a donor based quadruple quantum dot device, designed to host two singlet-triplet qubits fabricated by scanning tunnelling microscope lithography, with just two leads per qubit. The design is geometrically compact with each pair of dots independently controlled via one gate and one reservoir. The reservoirs both supply electrons for the dots and measure the singlet-triplet state of each qubit via dispersive sensing. We verify the locations of the four phosphorus donor dots via an electrostatic model of the device. We study one of the observed singlet-triplet states with a tunnel coupling of 39GHz and a S0 to T– decay of 2ms at zero detuning. We measure a 5GHz electrostatic interaction between two pairs of dots separated by 70nm. The results outline a low gate density pathway to a scalable 1D building block of atomic precision donors with dispersive readout.