Semiconductor quantum dots allow us to confine and manipulate individual electrons or holes. Lateral quantum dots in 2D electron/hole gases, defined electrostatically by applied gate voltages, offer the prospect of scalable spin qubit processors and other novel devices. In this talk, I’ll discuss two material platforms my group has focused on recently: (i) undoped GaAs heterostructures and (ii) silicon MOSFET devices. In undoped GaAs, a 2D carrier gas is induced electrostatically by a top gate, allowing both N-type and P-type gases to be realized with no intentional dopants present [1]. These devices are more challenging to fabricate, but have superior reproducibility and low disorder due to the lack of dopants. We demonstrate the diode behaviour of a lateral PN junction and characterize the electroluminescence that occurs under a sufficient PN bias voltage. We also demonstrate the first one-parameter single-electron pump (dynamic quantum dot) in undoped GaAs [2], and discuss how it can be used in metrology or be combined with a PN junction to realize an on-demand source of single photons. Part (ii) of the talk will focus on electron spin qubits in silicon, and the prospects for building a large-scale quantum information processor. We have proposed a node/network architecture for implementing the surface code that splits the scalability problem in two: internode entanglement distribution and intra-node operations [3]. Such an approach relaxes constraints on wiring densities and allows the co-integration of readout and multiplexing circuits. I will also discuss our experimental efforts to simplify the design of Si MOSFET quantum dots to reduce the number of electrodes required per dot [4].

References

1. Effects of biased and unbiased illuminations on dopant-free GaAs/AlGaAs 2DEGs, A. Shetty et al, J. Baugh, arXiv:2012.14370 (2020)
2. Non-adiabatic single-electron pump in a dopant-free GaAs/AlGaAs 2DEG. B. Buonacorsi et al, J. Baugh, arXiv:2102.13320 (2021)
3. Network architecture for a topological quantum computer in silicon, B. Buonacorsi et al, J. Baugh, Quantum Science and Technology 4, 025003 (2019).
4. Few-electrode design for silicon MOS quantum dots, E. B. Ramirez, F. Sfigakis, S. Kudva, J. Baugh, Semiconductor Science and Technology 35, 015002 (2019).