Randomized Benchmarking of Barrier versus Tilt Control of a Singlet-Triplet Qubit

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Robert E. Throckmorton
  • Xu-Chen Yang
  • Edwin Barnes
  • S. Das Sarma

Related Research Unit(s)

Detail(s)

Original languageEnglish
Article number216802
Journal / PublicationPhysical Review Letters
Volume118
Issue number21
Online published26 May 2017
Publication statusPublished - 26 May 2017

Abstract

Decoherence due to charge noise is one of the central challenges in using spin qubits in semiconductor quantum dots as a platform for quantum information processing. Recently, it has been experimentally demonstrated in both Si and GaAs singlet-triplet qubits that the effects of charge noise can be suppressed if qubit operations are implemented using symmetric barrier control instead of the standard tilt control. Here, we investigate the key issue of whether the benefits of barrier control persist over the entire set of single-qubit gates by performing randomized benchmarking simulations. We find the surprising result that the improvement afforded by barrier control depends sensitively on the amount of spin noise: for the minimal nuclear spin noise levels present in Si, the coherence time improves by more than 2 orders of magnitude whereas in GaAs, by contrast the coherence time is essentially the same for barrier and tilt control. However, we establish that barrier control becomes beneficial if qubit operations are performed using a new family of composite pulses that reduce gate times by up to 90%. With these optimized pulses, barrier control is the best way to achieve high-fidelity quantum gates in singlet-triplet qubits.

Citation Format(s)

Randomized Benchmarking of Barrier versus Tilt Control of a Singlet-Triplet Qubit. / Zhang, Chengxian; Throckmorton, Robert E. ; Yang, Xu-Chen et al.
In: Physical Review Letters, Vol. 118, No. 21, 216802, 26.05.2017.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review