Title: van der Waals-corrected density functional study of electric field noise heating in ion traps caused by electrode surface adsorbates

Abstract

Abstract In order to realize the full potential of ion trap quantum computers, an improved understanding is required of the motional heating that trapped ions experience. Experimental studies of the temperature-, frequency-, and ion–electrode distance-dependence of the electric field noise responsible for motional heating, as well as the noise before and after ion bombardment cleaning of trap electrodes, suggest that fluctuations of adsorbate dipoles are a likely source of so-called ‘anomalous heating,’ or motional heating of the trapped ions at a rate much higher than the Johnson noise limit. Previous computational studies have investigated how the fluctuation of model adsorbate dipoles affects anomalous heating. However, the way in which specific adsorbates affect the electric field noise has not yet been examined, and an electric dipole model employed in previous studies is only accurate for a small subset of possible adsorbates. Here, we analyze the behavior of both in-plane and out-of-plane vibrational modes of twenty-one adsorbate–electrode combinations within the independent fluctuating dipole model, utilizing accurate first principles computational methods to determine the surface-induced dipole moments. We find the chemical specificity of the adsorbate can change the electric field noise by seven orders of magnitude and specifically that soft in-plane modes ofmore » weakly-adsorbed hydrocarbons produce the greatest noise and ion heating. We discuss the dynamics captured by the fluctuating dipole model, namely the adsorbate-dependent turn-on temperature and electric field noise magnitude, and also discuss the model’s failure to reproduce the measured 1/ ω noise frequency scaling with a single adsorbate species. We suggest future research directions for improved, quantitatively predictive models based on extensions of the present framework to multiple interacting adsorbates.« less

Authors:

Ray, Keith G. ;

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• Search DOE PAGES for ORCID "0000-0002-6241-7472"

Rubenstein, Brenda M.; Gu, Wenze; Lordi, Vincenzo

Publication Date:

Wed May 29 00:00:00 EDT 2019

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1523543

Alternate Identifier(s):

OSTI ID: 1548368

Report Number(s):

LLNL-JRNL-734203
Journal ID: ISSN 1367-2630

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Published Article

Journal Name:

New Journal of Physics

Additional Journal Information:

Journal Name: New Journal of Physics Journal Volume: 21 Journal Issue: 5; Journal ID: ISSN 1367-2630

Publisher:

IOP Publishing

Country of Publication:

United Kingdom

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS; trapped ions; anomalous heating; surface adsorbates; decoherence; patch potential model