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ESE Seminar: “Engineering Quantum Processors in Silicon”
March 25, 2021 at 11:00 AM - 12:00 PM
Across the globe, physicists in academia and industry alike are competing to be the first to build a scalable universal quantum computer. Amongst the multitudes of quantum computing architectures, solid-state quantum processors based on spins in silicon are emerging as a strong contender. Silicon is an ideal material to host spin qubits: it supports long coherence times [1], has excellent prospects for scaling, and is ubiquitous in the semiconductor industry. While semiconductor spin qubits were proposed over two decades ago [2], it is only within the past few years that we have learned how to reliably fabricate and control multi-qubit devices in silicon.
In this seminar, I will describe our state-of-the-art four-qubit Si/SiGe quantum processor [3] and explain how we have overcome major barriers to realizing large-scale quantum computing in silicon. First, I will discuss charge control and spin-state readout in the device. Then, I will describe the use of an on-chip micromagnet to mediate electrically driven spin resonance [4-5]. Using this technique, we achieved site-selective qubit control with fidelities exceeding 99.9%. I will give an overview of our three primitive two-qubit gates—the decoupled-CZ gate [4], the resonant CNOT gate [5], and the resonant SWAP gate [6]—and discuss the limitations to control fidelities. Finally, I will show how these advances enable the development of large-scale quantum processors capable of complex quantum information processing.
References:
[1] Tyryshkin et al., Nature Mat. 11, 143 (2011)
[2] Loss and Divincenzo, Phys. Rev. A 57, 120 (1998)
[3] Sigillito et al., Phys. Rev. Applied 11, 061006 (2019)
[4] Watson et al., Nature 555, 633 (2018)
[5] Zajac, Sigillito, et al., Science 359, 439 (2018)
[6] Sigillito et al., npj Quantum Information 5, 110 (2019)
Anthony Sigillito
Associate Research Scholar, Princeton University
Anthony Sigillito is an associate research scholar in the Department of Electrical and Computer Engineering at Princeton University. He earned his PhD from the same department in 2017 as a Gordon Y.S. Wu fellow. His PhD research explored the physical processes that couple donor electron and nuclear spins in silicon to electric fields and led to the first demonstration of all-electrical nuclear spin control in silicon. Currently, he is working with Steve Lyon to fabricate quantum dot devices and study the spin coherence of electrons bound to the surface of superfluid helium films.
In his previous appointment, Anthony spent three years (2017-2020) as a Dicke Postdoctoral Fellow in Princeton’s Department of Physics working with Jason Petta. In this position, he led efforts to develop Si/SiGe-based quantum dot devices for quantum information processing applications. Some of his results include fabricating the first four-qubit quantum processor in silicon and demonstrating novel primitive gates for quantum dot devices, including the first demonstration of a CNOT gate in silicon.