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

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.

SUBMITTER: Weiss KM

PROVIDER: S-EPMC3814830 | biostudies-other | 2013

REPOSITORIES: biostudies-other

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

Weiss K M KM Miguel-Sanchez J J Elzerman J M JM

Scientific reports 20131101

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 ...[more]

PMID: 24177037

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