Two-qubit sweet spots for capacitively coupled exchange-only spin qubits

Abstract The implementation of high fidelity two-qubit gates is a bottleneck in the progress toward universal quantum computation in semiconductor quantum dot qubits. We study capacitive coupling between two triple quantum dot spin qubits encoded in the S = 1/2, S z = −1/2 decoherence-free subspace...

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Autores principales:	MengKe Feng, Lin Htoo Zaw, Teck Seng Koh
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Physics QC1-999 Electronic computers. Computer science QA75.5-76.95
Acceso en línea:	https://doaj.org/article/41840f1701634ea6b99d24a1144cc0d5
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spelling	oai:doaj.org-article:41840f1701634ea6b99d24a1144cc0d52021-12-02T16:09:44ZTwo-qubit sweet spots for capacitively coupled exchange-only spin qubits10.1038/s41534-021-00449-42056-6387https://doaj.org/article/41840f1701634ea6b99d24a1144cc0d52021-07-01T00:00:00Zhttps://doi.org/10.1038/s41534-021-00449-4https://doaj.org/toc/2056-6387Abstract The implementation of high fidelity two-qubit gates is a bottleneck in the progress toward universal quantum computation in semiconductor quantum dot qubits. We study capacitive coupling between two triple quantum dot spin qubits encoded in the S = 1/2, S z = −1/2 decoherence-free subspace—the exchange-only (EO) spin qubits. We report exact gate sequences for CPHASE and CNOT gates, and demonstrate theoretically, the existence of multiple two-qubit sweet spots (2QSS) in the parameter space of capacitively coupled EO qubits. Gate operations have the advantage of being all-electrical, but charge noise that couple to electrical parameters of the qubits cause decoherence. Assuming noise with a 1/f spectrum, two-qubit gate fidelities and times are calculated, which provide useful information on the noise threshold necessary for fault-tolerance. We study two-qubit gates at single and multiple parameter 2QSS. In particular, for two existing EO implementations—the resonant exchange (RX) and the always-on exchange-only (AEON) qubits—we compare two-qubit gate fidelities and times at positions in parameter space where the 2QSS are simultaneously single-qubit sweet spots (1QSS) for the RX and AEON. These results provide a potential route to the realization of high fidelity quantum computation.MengKe FengLin Htoo ZawTeck Seng KohNature PortfolioarticlePhysicsQC1-999Electronic computers. Computer scienceQA75.5-76.95ENnpj Quantum Information, Vol 7, Iss 1, Pp 1-11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999 Electronic computers. Computer science QA75.5-76.95
spellingShingle	Physics QC1-999 Electronic computers. Computer science QA75.5-76.95 MengKe Feng Lin Htoo Zaw Teck Seng Koh Two-qubit sweet spots for capacitively coupled exchange-only spin qubits
description	Abstract The implementation of high fidelity two-qubit gates is a bottleneck in the progress toward universal quantum computation in semiconductor quantum dot qubits. We study capacitive coupling between two triple quantum dot spin qubits encoded in the S = 1/2, S z = −1/2 decoherence-free subspace—the exchange-only (EO) spin qubits. We report exact gate sequences for CPHASE and CNOT gates, and demonstrate theoretically, the existence of multiple two-qubit sweet spots (2QSS) in the parameter space of capacitively coupled EO qubits. Gate operations have the advantage of being all-electrical, but charge noise that couple to electrical parameters of the qubits cause decoherence. Assuming noise with a 1/f spectrum, two-qubit gate fidelities and times are calculated, which provide useful information on the noise threshold necessary for fault-tolerance. We study two-qubit gates at single and multiple parameter 2QSS. In particular, for two existing EO implementations—the resonant exchange (RX) and the always-on exchange-only (AEON) qubits—we compare two-qubit gate fidelities and times at positions in parameter space where the 2QSS are simultaneously single-qubit sweet spots (1QSS) for the RX and AEON. These results provide a potential route to the realization of high fidelity quantum computation.
format	article
author	MengKe Feng Lin Htoo Zaw Teck Seng Koh
author_facet	MengKe Feng Lin Htoo Zaw Teck Seng Koh
author_sort	MengKe Feng
title	Two-qubit sweet spots for capacitively coupled exchange-only spin qubits
title_short	Two-qubit sweet spots for capacitively coupled exchange-only spin qubits
title_full	Two-qubit sweet spots for capacitively coupled exchange-only spin qubits
title_fullStr	Two-qubit sweet spots for capacitively coupled exchange-only spin qubits
title_full_unstemmed	Two-qubit sweet spots for capacitively coupled exchange-only spin qubits
title_sort	two-qubit sweet spots for capacitively coupled exchange-only spin qubits
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/41840f1701634ea6b99d24a1144cc0d5
work_keys_str_mv	AT mengkefeng twoqubitsweetspotsforcapacitivelycoupledexchangeonlyspinqubits AT linhtoozaw twoqubitsweetspotsforcapacitivelycoupledexchangeonlyspinqubits AT tecksengkoh twoqubitsweetspotsforcapacitivelycoupledexchangeonlyspinqubits
_version_	1718384405733441536

Two-qubit sweet spots for capacitively coupled exchange-only spin qubits

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