Coherent electron spin control in atomically precise donor systems

Speaker: 
Mr Ludwik Kranz
From: 
CQC2T at UNSW
When: 
4pm Thursday 21 September 2017
Where: 
CQC2T Conference Room, Level 2, Newton Building J12, UNSW Kensington Campus

In this talk we will discuss the progress in precision donor qubits in silicon. We will demonstrate the successful integration of a microwave transmission line onto two few electron double donor dot devices in silicon fabricated with the atomic precision of a scanning tunneling microscope (STM). The transmission line is used for magnetically driven Electron Spin Resonance (ESR) and a DC-coupled SET charge sensor is employed for single-shot spin readout. In the first device we use ESR spectroscopy to identify the characteristic hyperfine spectra of a single donor 1P and two-donor 2P dots. We demonstrate the importance of the electric field on the Stark shifting of the donors and how, from the hyperfine spectra, we can determine the distance between the donors within the 2P quantum dot. Atomistic NEMO modelling is used to determine possible donor configurations within the 2P dot in the Si crystal lattice. In the second device, we demonstrate coherent electron spin rotations via Rabi oscillations on a 2P dot with 3 electrons with T2*≈ 246ns. Using the Hahn spin echo sequence, we partially compensate for Overhauser field fluctuations in order to measure an electron spin decoherence time