Seminar by Benjamin Joecker

Modelling multi-qubit and high-spin donor quantum devices in silicon

Donor-based nano-devices in silicon offer a unique gateway into the quantum control of atomic-scale objects within a manufacturable solid-state hardware, and may be adopted for the construction of a large-scale quantum computer. Here, I will give a short introduction into the well-established spin-1/2 phosphorus donor and then dive deeper into two variations of this simple system. 

Heavier group V donors have high-spin nuclei, which exhibit a nuclear quadrupole moment. The coupling of the quadrupole to variations in the local charge environment allows for non-magnetic control of the nuclear spin. I will present simulations of nuclear electric[1] and nuclear acoustic[2] resonance experiments. 

Several realizations of multi-qubit gates with donors rely on the exchange interaction. Designing optimal devices with high-fidelity two-qubit gates requires accurate models of the dependence of the exchange interaction on lattice placement, orientations, and electric fields. Here, I use a full configuration interaction method in an multivalley effective mass theory framework to model the two-electron wavefunctions for different donor configurations.[3]

If there is time left, I might touch on simulations of error channels in quantum non-demolition measurements in donor spin devices.

[1] Nature 579.7798 (2020): 205-209

[2] Applied Physics Letters 119.17 (2021): 174001

[3] New Journal of Physics 23.7 (2021): 073007