## Switching between relaxation hotspots and coldspots in disordered spin qubits

No Thumbnail Available
##### Files
There are no files associated with this item.
2021
Preprint
Published
##### Abstract
We develop a valley-dependent envelope function theory that can describe the effects of arbitrary configurations of interface steps and miscuts on the qubit relaxation time. For a given interface roughness, we show how our theory can be used to find the valley-dependent dipole matrix elements, the valley splitting, and the spin-valley coupling as a function of the electromagnetic fields in a Si/SiGe quantum dot spin qubit. We demonstrate that our theory can quantitatively reproduce and explain the result of experimental measurements for the spin relaxation time with only a minimal set of free parameters. Investigating the sample dependence of spin relaxation, we find that at certain conditions for a disordered quantum dot, the spin-valley coupling vanishes. This, in turn, completely blocks the valley-induced qubit decay. We show that the presence of interface steps can in general give rise to a strongly anisotropic behavior of the spin relaxation time. Remarkably, by properly tuning the gate-induced out-of-plane electric field, it is possible to turn the spin-valley hotspot into a coldspot" at which the relaxation time is significantly prolonged and where the spin relaxation time is additionally first-order insensitive to the fluctuations of the magnetic field. This electrical tunability enables on-demand fast qubit reset and initialization that is critical for many quantum algorithms and error correction schemes. We, therefore, argue that the valley degree of freedom can be used as an advantage for Si spin qubits.
530 Physics
##### Cite This
ISO 690HOSSEINKHANI, Amin, Guido BURKARD, 2021. Switching between relaxation hotspots and coldspots in disordered spin qubits
BibTex
@unpublished{Hosseinkhani2021-05-03T09:48:58ZSwitc-53595,
year={2021},
title={Switching between relaxation hotspots and coldspots in disordered spin qubits},
author={Hosseinkhani, Amin and Burkard, Guido}
}

RDF
<rdf:RDF
xmlns:dcterms="http://purl.org/dc/terms/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:bibo="http://purl.org/ontology/bibo/"
xmlns:dspace="http://digital-repositories.org/ontologies/dspace/0.1.0#"
xmlns:foaf="http://xmlns.com/foaf/0.1/"
xmlns:void="http://rdfs.org/ns/void#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#" >
<dcterms:title>Switching between relaxation hotspots and coldspots in disordered spin qubits</dcterms:title>
<dc:rights>terms-of-use</dc:rights>
<dc:language>eng</dc:language>
<dcterms:issued>2021-05-03T09:48:58Z</dcterms:issued>
<dcterms:available rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2021-05-05T11:40:46Z</dcterms:available>
<dc:contributor>Hosseinkhani, Amin</dc:contributor>
<dcterms:abstract xml:lang="eng">We develop a valley-dependent envelope function theory that can describe the effects of arbitrary configurations of interface steps and miscuts on the qubit relaxation time. For a given interface roughness, we show how our theory can be used to find the valley-dependent dipole matrix elements, the valley splitting, and the spin-valley coupling as a function of the electromagnetic fields in a Si/SiGe quantum dot spin qubit. We demonstrate that our theory can quantitatively reproduce and explain the result of experimental measurements for the spin relaxation time with only a minimal set of free parameters. Investigating the sample dependence of spin relaxation, we find that at certain conditions for a disordered quantum dot, the spin-valley coupling vanishes. This, in turn, completely blocks the valley-induced qubit decay. We show that the presence of interface steps can in general give rise to a strongly anisotropic behavior of the spin relaxation time. Remarkably, by properly tuning the gate-induced out-of-plane electric field, it is possible to turn the spin-valley hotspot into a coldspot" at which the relaxation time is significantly prolonged and where the spin relaxation time is additionally first-order insensitive to the fluctuations of the magnetic field. This electrical tunability enables on-demand fast qubit reset and initialization that is critical for many quantum algorithms and error correction schemes. We, therefore, argue that the valley degree of freedom can be used as an advantage for Si spin qubits.</dcterms:abstract>
<dc:creator>Burkard, Guido</dc:creator>
<dcterms:rights rdf:resource="https://rightsstatements.org/page/InC/1.0/"/>
<dcterms:isPartOf rdf:resource="https://kops.uni-konstanz.de/server/rdf/resource/123456789/41"/>
<bibo:uri rdf:resource="https://kops.uni-konstanz.de/handle/123456789/53595"/>
<dc:creator>Hosseinkhani, Amin</dc:creator>
<foaf:homepage rdf:resource="http://localhost:8080/"/>
<dspace:isPartOfCollection rdf:resource="https://kops.uni-konstanz.de/server/rdf/resource/123456789/41"/>
<dc:contributor>Burkard, Guido</dc:contributor>
<dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2021-05-05T11:40:46Z</dc:date>
<void:sparqlEndpoint rdf:resource="http://localhost/fuseki/dspace/sparql"/>
</rdf:Description>
</rdf:RDF>

Yes