Probing relaxation times in graphene quantum dots

Graphene quantum dots are attractive candidates for solid-state quantum bits. In fact, the predicted weak spin-orbit and hyperfine interaction promise spin qubits with long coherence times. Graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filli...

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Main Authors:	Volk, Christian, Neumann, Christoph, Kazarski, Sebastian, Fringes, Stefan, Engels, Stephan, Haupt, Federica, Müller, André, Stampfer, Christoph
Format:	Online
Language:	English
Published:	Nature Pub. Group 2013
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3644082/

id	pubmed-3644082
recordtype	oai_dc
spelling	pubmed-36440822013-05-17 Probing relaxation times in graphene quantum dots Volk, Christian Neumann, Christoph Kazarski, Sebastian Fringes, Stefan Engels, Stephan Haupt, Federica Müller, André Stampfer, Christoph Article Graphene quantum dots are attractive candidates for solid-state quantum bits. In fact, the predicted weak spin-orbit and hyperfine interaction promise spin qubits with long coherence times. Graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filling sequence and electron-hole crossover. However, their relaxation dynamics remain largely unexplored. This is mainly due to challenges in device fabrication, in particular concerning the control of carrier confinement and the tunability of the tunnelling barriers, both crucial to experimentally investigate decoherence times. Here we report pulsed-gate transient current spectroscopy and relaxation time measurements of excited states in graphene quantum dots. This is achieved by an advanced device design that allows to individually tune the tunnelling barriers down to the low megahertz regime, while monitoring their asymmetry. Measuring transient currents through electronic excited states, we estimate a lower bound for charge relaxation times on the order of 60–100 ns. Nature Pub. Group 2013-04-23 /pmc/articles/PMC3644082/ /pubmed/23612294 http://dx.doi.org/10.1038/ncomms2738 Text en Copyright © 2013, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. http://creativecommons.org/licenses/by-nc-nd/3.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Volk, Christian Neumann, Christoph Kazarski, Sebastian Fringes, Stefan Engels, Stephan Haupt, Federica Müller, André Stampfer, Christoph
spellingShingle	Volk, Christian Neumann, Christoph Kazarski, Sebastian Fringes, Stefan Engels, Stephan Haupt, Federica Müller, André Stampfer, Christoph Probing relaxation times in graphene quantum dots
author_facet	Volk, Christian Neumann, Christoph Kazarski, Sebastian Fringes, Stefan Engels, Stephan Haupt, Federica Müller, André Stampfer, Christoph
author_sort	Volk, Christian
title	Probing relaxation times in graphene quantum dots
title_short	Probing relaxation times in graphene quantum dots
title_full	Probing relaxation times in graphene quantum dots
title_fullStr	Probing relaxation times in graphene quantum dots
title_full_unstemmed	Probing relaxation times in graphene quantum dots
title_sort	probing relaxation times in graphene quantum dots
description	Graphene quantum dots are attractive candidates for solid-state quantum bits. In fact, the predicted weak spin-orbit and hyperfine interaction promise spin qubits with long coherence times. Graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filling sequence and electron-hole crossover. However, their relaxation dynamics remain largely unexplored. This is mainly due to challenges in device fabrication, in particular concerning the control of carrier confinement and the tunability of the tunnelling barriers, both crucial to experimentally investigate decoherence times. Here we report pulsed-gate transient current spectroscopy and relaxation time measurements of excited states in graphene quantum dots. This is achieved by an advanced device design that allows to individually tune the tunnelling barriers down to the low megahertz regime, while monitoring their asymmetry. Measuring transient currents through electronic excited states, we estimate a lower bound for charge relaxation times on the order of 60–100 ns.
publisher	Nature Pub. Group
publishDate	2013
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3644082/
_version_	1611975188091502592

Probing relaxation times in graphene quantum dots

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