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Magnetically tunable singlet-triplet spin qubit in a four-electron InGaAs coupled quantum dot

Weiss, KM; Miguel-Sanchez, J; Elzerman, JM; (2013) Magnetically tunable singlet-triplet spin qubit in a four-electron InGaAs coupled quantum dot. SCIENTIFIC REPORTS , 3 , Article ARTN 3121. 10.1038/srep03121. Green open access

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Abstract

A pair of self-assembled InGaAs quantum dots filled with two electrons can act as a singlet-triplet spin qubit that is robust against nuclear spin fluctuations as well as charge noise. This results in a T2* coherence time two orders of magnitude longer than that of a single electron, provided the qubit is operated at a particular ‘‘sweet spot’’ in gate voltage. However, at this fixed operating point the ground-state splitting can no longer be tuned into resonance with e.g. another qubit, limiting the options for coupling multiple qubits. Here, we propose using a four-electron coupled quantum dot to implement a singlet-triplet qubit that features a magnetically tunable level splitting. As a first step towards full experimental realization of this qubit design, we use optical spectroscopy to demonstrate the tunability of the four-electron singlet-triplet splitting in a moderate magnetic field.

Type: Article
Title: Magnetically tunable singlet-triplet spin qubit in a four-electron InGaAs coupled quantum dot
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/srep03121
Publisher version: http://dx.doi.org/10.1038/srep03121
Additional information: © 2013 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 3.0 Unported license. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0 PubMed ID: 24177037
Keywords: Qubits; Quantum information
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: http://discovery.ucl.ac.uk/id/eprint/1410660
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