| AVS 64th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology Division | Tuesday Sessions |
| Session NS+EM+MI+SS-TuM |
| Session: | Nanoscale Electronics and Magnetism |
| Presenter: | Michelle Simmons, University of New South Wales, Australia |
| Correspondent: | Click to Email |
Extremely long electron spin coherence times have recently been demonstrated in isotopically pure Si-28 [1] making silicon one of the most promising semiconductor materials for spin based quantum information. The two level spin state of single electrons bound to shallow phosphorus donors in silicon in particular provide well defined, reproducible qubits [2] and represent a promising system for a scalable quantum computer in silicon. An important challenge in these systems is the realisation of a two-qubit gate, where we can both position donors with respect to each other for controllable exchange coupling and with respect to charge sensors for individually addressing and reading out the spin state of each donor with high fidelity.
To date we have demonstrated using scanning tunneling microscope hydrogen lithography how we can precisely position individual P donors in Si [3] aligned with nanoscale precision to local control gates [4] and can initialize, manipulate, and read-out the spin states [5,6] with high fidelity. We now demonstrate how we can achieve record single-electron readout fidelity for each of two donor based dots of 99.8%, above the surface-code fault tolerant threshold. We show how by engineering the quantum dots to contain multiple donors we can achieve spin lifetimes up to 16 times longer than single donors. Finally we show how by optimising the interdonor separation and using asymmetric confinement potentials we can create controllable exchange coupling in these devices. With the recent demonstration of ultra-low noise in these all epitaxial devices [7] these results confirm the enormous potential of atomic-scale qubits in silicon.
[1] J. T. Muhonen et al., Nature Nanotechnology 9, 986 (2014).
[2] B.E. Kane, Nature 393, 133 (1998).
[3] M. Fuechsle et al., Nature Nanotechnology 7, 242 (2012).
[4] B. Weber et al., Science 335, 6064 (2012).
[5] H. Buch et al., Nature Communications 4, 2017 (2013).
[6] T.F. Watson et al., Physical Review Letters 115, 166806 (2015).
[7] S. Shamim et al., Nano Letters 16, 5779 (2016).