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Low-temperature silicon epitaxy for atomic precision devices

ECS Transactions

Anderson, Evan M.; Katzenmeyer, Aaron M.; Luk, Ting S.; Campbell, DeAnna M.; Marshall, Michael T.; Bussmann, Ezra B.; Ohlhausen, J.A.; Lu, Ping L.; Kotula, Paul G.; Ward, Daniel R.; Lu, Tzu-Ming L.; Misra, Shashank M.

We discuss chemical, structural, and ellipsometry characterization of low temperature epitaxial Si. While low temperature growth is not ideal, we are still able to prepare crystalline Si to cap functional atomic precision devices.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

A silicon metal-oxide-semiconductor electron spin-orbit qubit

Nature Communications

Jock, Ryan M.; Jacobson, Noah T.; Harvey-Collard, Patrick; Mounce, Andrew M.; Srinivasa, Vanita S.; Ward, Daniel R.; Anderson, John M.; Manginell, Ronald P.; Wendt, J.R.; Rudolph, Martin R.; Pluym, Tammy P.; Laros, James H.; Baczewski, Andrew D.; Witzel, Wayne W.; Carroll, Malcolm

The silicon metal-oxide-semiconductor (MOS) material system is a technologically important implementation of spin-based quantum information processing. However, the MOS interface is imperfect leading to concerns about 1/f trap noise and variability in the electron g-factor due to spin-orbit (SO) effects. Here we advantageously use interface-SO coupling for a critical control axis in a double-quantum-dot singlet-triplet qubit. The magnetic fieldorientation dependence of the g-factors is consistent with Rashba and Dresselhaus interface-SO contributions. The resulting all-electrical, two-Axis control is also used to probe the MOS interface noise. The measured inhomogeneous dephasing time, T2m, of 1.6 ?s is consistent with 99.95% 28Si enrichment. Furthermore, when tuned to be sensitive to exchange fluctuations, a quasi-static charge noise detuning variance of 2 μeV is observed, competitive with low-noise reports in other semiconductor qubits. This work, therefore, demonstrates that the MOS interface inherently provides properties for two-Axis qubit control, while not increasing noise relative to other material choices.

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TYPE Journal Article YEAR 2018
DOIOSTIScopus

All-optical lithography process for contacting nanometer precision donor devices

Applied Physics Letters

Ward, Daniel R.; Marshall, Michael T.; Campbell, DeAnna M.; Lu, Tzu-Ming L.; Laros, James H.; Scrymgeour, David S.; Bussmann, Ezra B.; Misra, Shashank M.

We describe an all-optical lithography process that can make electrical contact to nanometer-precision donor devices fabricated in silicon using scanning tunneling microscopy (STM). This is accomplished by implementing a cleaning procedure in the STM that allows the integration of metal alignment marks and ion-implanted contacts at the wafer level. Low-temperature transport measurements of a patterned device establish the viability of the process.

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TYPE Journal Article YEAR 2017
DOIOSTIScopus

Effects of charge noise on a pulse-gated singlet-triplet S - T- qubit

Physical Review B

Qi, Zhenyi; Wu, X.; Ward, Daniel R.; Prance, J.R.; Kim, Dohun; Laros, James H.; Mohr, R.T.; Shi, Zhan; Savage, D.E.; Lagally, M.G.; Eriksson, M.A.; Coppersmith, S.N.; Friesen, Mark; Vavilov, M.G.

We study the dynamics of a pulse-gated semiconductor double-quantum-dot qubit. In our experiments, the qubit coherence times are relatively long, but the visibility of the quantum oscillations is low. We show that these observations are consistent with a theory that incorporates decoherence arising from charge noise that gives rise to detuning fluctuations of the double dot. Because effects from charge noise are largest near the singlet-triplet avoided level crossing, the visibility of the oscillations is low when the singlet-triplet avoided level crossing occurs in the vicinity of the charge degeneracy point crossed during the manipulation, but there is only modest dephasing at the large detuning value at which the quantum phase accumulates. This theory agrees well with experimental data and predicts that the visibility can be increased greatly by appropriate tuning of the interdot tunneling rate.

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TYPE Journal Article YEAR 2017
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Results 26–50 of 77
Results 26–50 of 77