Silicon MOS quantum dots for spin-based quantum computation

Quantum computers are expected to outperform conventional computers for a range of important problems, from molecular simulation to search algorithms, once they can be scaled up to large numbers of quantum bits (qubits), typically millions. Spin qubits in silicon MOS quantum dots are one of the big contenders for a scalable, solid state-based quantum computing platform. Here, the qubits are encoded as the spin states of individual electrons confined in electrostatically-gated quantum dots. The great potential of this system has been demonstrated through various experiments over the last few years, with coherence times of up to T2=28 ms, single qubit control fidelities of 99.96%, and two-qubit control fidelities of 98%.
In my presentation, I will give an introduction to the SiMOS quantum dot spin qubits that we employ at UNSW Sydney. I will showcase some of the key experiments of the last years related to experimental challenges of scaling a silicon-CMOS based quantum processor up to the millions of qubits that will be required for fault-tolerant quantum computing. In particular, I will present our results of operating silicon spin qubits at temperatures above 1 K [1,2] that are important for the integration of conventional CMOS control electronics with the qubit system, and global control techniques that allow for the control of many qubits simultaneously.

[1] C. H. Yang, R. C. C. Leon, J. C. C. Hwang, A. Saraiva, T. Tanttu, W. Huang, J. Camirand Lemyre, K. W. Chan, K. Y. Tan, F. E. Hudson, K. M. Itoh, A. Morello, M. Pioro-Ladrière, A. Laucht, and A. S. Dzurak. Operation of a silicon quantum processor unit cell above one kelvin. Nature 580, 350 (2020).
[2] J. Y. Huang, W. H. Lim, R. C. C. Leon, C. H. Yang, F. E. Hudson, C. C. Escott, A. Saraiva, A. S. Dzurak, and A. Laucht. A High-Sensitivity Charge Sensor for Silicon Qubits above 1 K. Nano Letters 21, 6328 (2021).
[3] E. Vahapoglu, J. P. Slack-Smith, R. C. C. Leon, W. H. Lim, F. E. Hudson, T. Day, J. D. Cifuentes, T. Tanttu, C. H. Yang, A. Saraiva, M. L. W. Thewalt, A. Laucht, A. S. Dzurak, and J. J. Pla. Coherent control of electron spin qubits in silicon using a global field. arXiv:2107.14622 (2021).

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