High-fidelity operation and algorithmic initialisation of spin qubits above one kelvin

• URL: http://arxiv.org/abs/2308.02111v2
• Date: Fri, 18 Aug 2023 04:51:01 GMT
• Title: High-fidelity operation and algorithmic initialisation of spin qubits above one kelvin
• Authors: Jonathan Y. Huang, Rocky Y. Su, Wee Han Lim, MengKe Feng, Barnaby van Straaten, Brandon Severin, Will Gilbert, Nard Dumoulin Stuyck, Tuomo Tanttu, Santiago Serrano, Jesus D. Cifuentes, Ingvild Hansen, Amanda E. Seedhouse, Ensar Vahapoglu, Nikolay V. Abrosimov, Hans-Joachim Pohl, Michael L. W. Thewalt, Fay E. Hudson, Christopher C. Escott, Natalia Ares, Stephen D. Bartlett, Andrea Morello, Andre Saraiva, Arne Laucht, Andrew S. Dzurak, and Chih Hwan Yang
• Abstract summary: We tune up and operate spin qubits in silicon above 1 kelvin, with fidelities in the range required for fault-tolerant operation at such temperatures. We demonstrate a single-qubit Clifford gate fidelity of 99.85 per cent, and a two-qubit gate fidelity of 98.92 per cent.
• Score: 0.2398431050362945
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The encoding of qubits in semiconductor spin carriers has been recognised as a promising approach to a commercial quantum computer that can be lithographically produced and integrated at scale. However, the operation of the large number of qubits required for advantageous quantum applications will produce a thermal load exceeding the available cooling power of cryostats at millikelvin temperatures. As the scale-up accelerates, it becomes imperative to establish fault-tolerant operation above 1 kelvin, where the cooling power is orders of magnitude higher. Here, we tune up and operate spin qubits in silicon above 1 kelvin, with fidelities in the range required for fault-tolerant operation at such temperatures. We design an algorithmic initialisation protocol to prepare a pure two-qubit state even when the thermal energy is substantially above the qubit energies, and incorporate radio-frequency readout to achieve fidelities up to 99.34 per cent for both readout and initialisation. Importantly, we demonstrate a single-qubit Clifford gate fidelity of 99.85 per cent, and a two-qubit gate fidelity of 98.92 per cent. These advances overcome the fundamental limitation that the thermal energy must be well below the qubit energies for high-fidelity operation to be possible, surmounting a major obstacle in the pathway to scalable and fault-tolerant quantum computation.

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