In this talk, I will give an overview on our vision on quantum computing with electron spin qubits, and discuss the progress and challenges in realizing fault-tolerant, fully integrated silicon quantum circuits [1, 2]. I will first present our work on characterizing gate fidelities, including the realization of a high-fidelity two-qubit gate that meets the requirement for implementing quantum error correction [3, 4, 5, 6]. Then I will steer the focus to quantum control of spin qubits using a cryo-CMOS chip, named "Horse Ridge", which is a first step towards solving the wiring issues at the quantum-classical interface [2, 7]. Finally, I will introduce our recent spin qubit experiments, in particular the realization of the first two-qubit logic between distant spins in silicon, which is achieved by using an on-chip superconducting resonator [8].
 

[1] L. M. K. Vandersypen, et al., npj Quantum Information 3, 34 (2017).
[2] X. Xue, et al., IEEE Nanotechnology Magazine 17, 1, 31-40 (2023)
[3] J. Helsen, X. Xue, et al., npj Quantum Information 5, 71 (2019)
[4] X. Xue, et al., PRX 9, 021011 (2019).
[5] X. Xue, et al., PRX 10, 021006 (2020).
[6] X. Xue, et al., Nature 601, 343–347 (2022).
[7] X. Xue, et al., Nature 593, 205–210 (2021).
[8] J. Dijkema, X. Xue (equal contribution), et al., arXiv:2310.16805 (2023).
 

Xiao Xue is a postdoc researcher at QuTech, Delft University of Technology (TU Delft) and currently leads a National Growth Fund — Quantum Technology 2023 of the Netherlands.  He received his BSc degree in physics from the University of Science and Technology of China (USTC) in 2014, and PhD cum laude (the highest honor of PhD graduate) from TU Delft in 2022, supervised by Prof. Lieven M. K. Vandersypen. Before his PhD, he was a graduate student in Tsinghua University working on graphene quantum dots and a research intern in École Polytechnique Fédérale de Lausanne (EPFL) working on superconducting cavity optomechanics. In 2023, he wins the Steven Hoogendijk Prize, which is awarded every two years by the Bataafsch Genootschap der Proefondervindelijke Wijsbegeerte (Batavian Society of Experimental Philosophy).

His research focuses on quantum information processing with spin qubits in silicon quantum dots. His expertise includes benchmarking and optimization of quantum logic, circuit quantum electrodynamics with spin qubits, and quantum control using cryogenic CMOS circuitry. He demonstrated the first high-fidelity two-qubit logic in silicon crossing the error correction threshold and the first universal control over spin qubits with a cryo-CMOS controller -- "Horse Ridge". Now his main interest is using superconducting resonators as quantum links to network distant spin qubits on a chip. He recently reported the first realization of a distant two-qubit gate in silicon, which paves the way for modular quantum computation. So far, he has conducted multiple high-impact studies, including two first-author publications in Nature and two in PRX. He has co-authored a number of conference proceedings such as ISSCC and IEDM, and he owns 1 US patent. In addition, he serves as a reviewer for PRL, PRX Quantum, PRA, PRB, npj Quantum Information, Quantum, Nano Letters, Quantum Science and Technology, etc.

Please contact phweb@ust.hk should you have questions about the talk.