Abstract
Silicon spin qubits are promising candidates for realizing large-scale quantum processors, benefitting from a magnetically quiet host material and the prospects of leveraging the mature silicon device fabrication industry. We report the measurement of an electron spin in a singly occupied gate-defined quantum dot, fabricated using CMOS-compatible processes at the 300-mm wafer scale. For readout, we employ spin-dependent tunneling combined with a low-footprint single-lead quantum-dot charge sensor, measured using rf gate reflectometry. We demonstrate spin readout in two devices using this technique, obtaining valley splittings in the range 0.5–0.7 meV using excited-state spectroscopy, and measure a maximum electron-spin relaxation time (T1) of 9±3 s at 1 T. These long lifetimes indicate the silicon-nanowire geometry and fabrication processes employed here show a great deal of promise for qubit devices, while the spin-readout method demonstrated here is well suited to a variety of scalable architectures.4 MoreReceived 16 May 2020Revised 12 October 2020Accepted 24 February 2021DOI:https://doi.org/10.1103/PRXQuantum.2.010353Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasQuantum computationPhysical SystemsQuantum dotsCondensed Matter, Materials & Applied Physics
Highlights
Spin qubits in silicon have been shown to fulfil most of the requirements to realize a quantum computer [1], including high-fidelity qubit manipulation [2], single-shot readout [3,4,5], and long coherence times [6,7]
We report the measurement of an electron spin in a singly occupied gate-defined quantum dot, fabricated using CMOS-compatible processes at the 300-mm wafer scale
Remaining challenges to realize a silicon quantum processor include building on recent demonstrations of two-qubit gates [8,9,10,11] to reach the fault-tolerant threshold, as well as showing how scalable control and measurement of silicon qubits can be achieved in a way that is compatible with their high intrinsic density
Summary
Spin qubits in silicon have been shown to fulfil most of the requirements to realize a quantum computer [1], including high-fidelity qubit manipulation [2], single-shot readout [3,4,5], and long coherence times [6,7]. Standard three-terminal charge sensors such as the quantum point contact (QPC) or single-electron transistor (SET) have achieved spin-readout fidelities as high as 99.9% in 6 μs [22,23] in dc mode and 99% in 1.6 μs in rf mode [4]. These sensors require two charge reservoirs near the qubit, complicating the use of this method at scale in dense qubit arrays.
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