Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1106.1949 · Physical Review A

Microscopic model of electric-field-noise heating in ion traps

Arghavan Safavi-Naini, Peter Rabl, Philippe F. Weck, H. R. Sadeghpour

Published Aug 22, 2011• 91 citations
arXivHTMLPDF

Abstract

Motional heating of ions in microfabricated traps is one of the open challenges hindering experimental realizations of large-scale quantum processing devices. Recently, a series of measurements of the heating rates in surface-electrode ion traps characterized their frequency, distance, and temperature dependencies, but our understanding of the microscopic origin of this noise remains incomplete. In this work we develop a theoretical model for the electric field noise which is associated with a random distribution of adsorbed atoms on the trap electrode surface. By using first-principles calculations of the fluctuating dipole moments of the adsorbed atoms we evaluate the distance, frequency, and temperature dependence of the resulting electric field fluctuation spectrum. Our theory reproduces correctly the ${d}^{\ensuremath{-}4}$ dependence with distance of the ion from the electrode surface and calculates the noise spectrum beyond the standard scenario of two-level fluctuators by incorporating all the relevant vibrational states. Our model predicts a regime of $1/f$ noise which commences at roughly the frequency of the fundamental phonon transition rate and a thermally activated noise spectrum which for higher temperatures exhibits a crossover as a function of frequency.

DOI
10.1103/physreva.84.023412

Related papers

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

Keith G. Ray, Brenda M Rubenstein, Wenze Gu +1 more

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 of 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.

arXiv:1810.10199•New Journal of Physics•Apr 11, 2019•10 citations

1/ω electric-field noise in surface ion traps from correlated adsorbate dynamics

Benjamin L. Foulon, Keith G. Ray, Chang-Eun Kim +3 more

Ion traps are promising architectures for implementing quantum computers, but they suffer from excessive ``anomalous'' ion motional heating that limit their overall coherence and practicality for scalable quantum computing. The exact microscopic origins of anomalous heating remain an open question, but experiments point to adsorbates on trap electrodes as one likely source. Many different models of anomalous heating have been proposed, but these models have yet to pinpoint the atomistic origin of the experimentally observed $1/\ensuremath{\omega}$ electric-field noise scaling seen in ion traps at frequencies between 0.1--10 MHz. In this work, we show that a model based on previously proposed surface-induced dipole fluctuations on adsorbates, but which also incorporates interparticle interaction dynamics through molecular dynamics simulations of up to multiple monolayers of adsorbates, gives rise to $1/\ensuremath{\omega}$ frequency scaling at the MHz frequencies typically employed in ion traps. These results demonstrate that moderate-to-high densities of adsorbates can give rise to a set of activated motions that produce the $1/\ensuremath{\omega}$ noise observed in ion traps and that collective adsorbate motions produce the observed noise spectra that a noninteracting model does not capture.

Physical Review A•Jan 19, 2022•8 citations

Electric-field noise from thermally activated fluctuators in a surface ion trap

Crystal Noel, Maya Berlin-Udi, Clemens Matthiesen +4 more

We probe electric-field noise near the metal surface of an ion-trap chip in the temperature range from 295 to 530 K. We observe a nontrivial temperature dependence with the noise amplitude at 1 MHz frequency saturating around 500 K. Measurements of the noise spectrum reveal a $1/{f}^{\ensuremath{\alpha}\ensuremath{\approx}1}$ dependence and a small decrease in $\ensuremath{\alpha}$ between low and high temperatures. This behavior can be explained by considering noise from a distribution of thermally activated two-level fluctuators with activation energies between 0.35 and 0.65 eV. Processes in this energy range may be relevant to understanding electric-field noise in ion traps; for example, defect motion in the solid state and surface adsorbate binding energies. The study of these processes may aid in identification of the origin of excess electric-field noise in ion traps---a major source of ion motional decoherence limiting the performance of surface traps as quantum devices.

arXiv:1809.05624•Physical Review A•Jun 26, 2019•41 citations

Influence of monolayer contamination on electric-field-noise heating in ion traps

Arghavan Safavi-Naini, E. Kim, Philippe F. Weck +2 more

Electric field noise is a hinderance to the assembly of large-scale quantum computers based on entangled trapped ions. Apart from ubiquitous technical noise, experimental studies of trapped ion heating have revealed additional limiting contributions to this noise, originating from atomic processes on the electrode surfaces. In a recent work [Safavi-Naini, Rabl, Weck, and Sadeghpour, Phys. Rev. A 84, 023412 (2011)] we described a microscopic model for this excess electric field noise, which points a way towards a more systematic understanding of surface adsorbates as progenitors of electric field jitter noise. Here, we address the impact of surface monolayer contamination on adsorbate-induced noise processes. Using exact numerical calculations for H and N atomic monolayers on a Au(111) surface, representing opposite extremes of physisorption and chemisorption, we show that an additional monolayer can significantly affect the noise power spectrum and, respectively, enhance and suppress the heating rates.

arXiv:1210.0044•Physical Review A•Feb 22, 2013•33 citations

Effects of electrode surface roughness on motional heating of trapped ions

Kuan-Yu Lin, Guang Hao Low, Isaac L. Chuang

Electric-field noise is a major source of motional heating in trapped-ion quantum computation. While the influence of trap-electrode geometries on electric-field noise has been studied in patch potential and surface adsorbate models, only smooth surfaces are accounted for by current theory. The effects of roughness, a ubiquitous feature of surface electrodes, are poorly understood. We investigate its impact on electric-field noise by deriving a rough-surface Green's function and evaluating its effects on adsorbate-surface binding energies. At cryogenic temperatures, heating-rate contributions from adsorbates are predicted to exhibit an exponential sensitivity to local surface curvature, leading to either a large net enhancement or suppression over smooth surfaces. For typical experimental parameters, orders-of-magnitude variations in total heating rates can occur depending on the spatial distribution of adsorbates. Through careful engineering of electrode surface profiles, our results suggests that heating rates can be tuned over orders of magnitudes.

arXiv:1605.02808•Physical Review A•Jul 20, 2016•17 citations

High temperature studies of electric-field noise in a surface ion trap

Crystal Noel

Electric-field noise is a major limiting factor in the performance of ion traps and other quantum devices. Despite intensive research over the past decade, the nature and cause of electric field noise near surfaces is not well understood. This dissertation reports the high- temperature dependence of electric-field noise above an Al-Cu surface using a trapped 40Ca+ ion as a probe.We employ a novel setup with a surface ion trap mounted on a heater for studies of the temperature dependence of electric-field noise. To characterize the Al-Cu material, we explore the effects of heat treatment through ex situ annealing followed by inspection in a scanning electron microscope. To calibrate the temperature of the trap, we demonstrate the use of thermal imaging for monitoring the temperature of an ion trap in vacuum.The temperature and frequency dependence of electric-field noise above the surface is measured using the heating rate of a single ion in a surface-electrode Paul trap. We find that the heating rate saturates at temperatures greater than 450 K. We find that the frequency dependence shows a 1/f behavior, and has a lower frequency scaling exponent at high temperatures than at room temperature. We show that these results are a reflection of the surface-related noise by eliminating other possible sources of noise.Building on historical data for resistance fluctuations in thin films, we develop the thermally-activated fluctuator model to describe the results. We find that a broad distribution of fluctuators with energy barriers peaked around 0.5 eV accurately models both the temperature and frequency dependence of the electric-field noise measured. We present the interpretation of this model as a way to infer that the cause of electric-field noise in the trap is likely defect motion in the metal surface, connecting the problems faced in ion trapping to a large body of work in solid state physics.

•Jan 1, 2019•0 citations
Motional heating of ions in microfabricated traps is one of the open challenges hindering experimental realizations of large-scale quantum processing devices. Recently, a series of measurements of the heating rates in surface-electrode ion traps characterized their frequency, distance, and temperature dependencies, but our understanding of the microscopic origin of this noise remains incomplete. In this work we develop a theoretical model for the electric field noise which is associated with a random distribution of adsorbed atoms on the trap electrode surface. By using first-principles calculations of the fluctuating dipole moments of the adsorbed atoms we evaluate the distance, frequency, and temperature dependence of the resulting electric field fluctuation spectrum. Our theory reproduces correctly the d\ensuremath−4{d}^{\ensuremath{-}4}d\ensuremath−4 dependence with distance of the ion from the electrode surface and calculates the noise spectrum beyond the standard scenario of two-level fluctuators by incorporating all the relevant vibrational states. Our model predicts a regime of 1/f1/f1/f noise which commences at roughly the frequency of the fundamental phonon transition rate and a thermally activated noise spectrum which for higher temperatures exhibits a crossover as a function of frequency.
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 of 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.
Ion traps are promising architectures for implementing quantum computers, but they suffer from excessive ``anomalous'' ion motional heating that limit their overall coherence and practicality for scalable quantum computing. The exact microscopic origins of anomalous heating remain an open question, but experiments point to adsorbates on trap electrodes as one likely source. Many different models of anomalous heating have been proposed, but these models have yet to pinpoint the atomistic origin of the experimentally observed $1/\ensuremath{\omega}$ electric-field noise scaling seen in ion traps at frequencies between 0.1--10 MHz. In this work, we show that a model based on previously proposed surface-induced dipole fluctuations on adsorbates, but which also incorporates interparticle interaction dynamics through molecular dynamics simulations of up to multiple monolayers of adsorbates, gives rise to $1/\ensuremath{\omega}$ frequency scaling at the MHz frequencies typically employed in ion traps. These results demonstrate that moderate-to-high densities of adsorbates can give rise to a set of activated motions that produce the $1/\ensuremath{\omega}$ noise observed in ion traps and that collective adsorbate motions produce the observed noise spectra that a noninteracting model does not capture.
We probe electric-field noise near the metal surface of an ion-trap chip in the temperature range from 295 to 530 K. We observe a nontrivial temperature dependence with the noise amplitude at 1 MHz frequency saturating around 500 K. Measurements of the noise spectrum reveal a $1/{f}^{\ensuremath{\alpha}\ensuremath{\approx}1}$ dependence and a small decrease in $\ensuremath{\alpha}$ between low and high temperatures. This behavior can be explained by considering noise from a distribution of thermally activated two-level fluctuators with activation energies between 0.35 and 0.65 eV. Processes in this energy range may be relevant to understanding electric-field noise in ion traps; for example, defect motion in the solid state and surface adsorbate binding energies. The study of these processes may aid in identification of the origin of excess electric-field noise in ion traps---a major source of ion motional decoherence limiting the performance of surface traps as quantum devices.
Electric field noise is a hinderance to the assembly of large-scale quantum computers based on entangled trapped ions. Apart from ubiquitous technical noise, experimental studies of trapped ion heating have revealed additional limiting contributions to this noise, originating from atomic processes on the electrode surfaces. In a recent work [Safavi-Naini, Rabl, Weck, and Sadeghpour, Phys. Rev. A 84, 023412 (2011)] we described a microscopic model for this excess electric field noise, which points a way towards a more systematic understanding of surface adsorbates as progenitors of electric field jitter noise. Here, we address the impact of surface monolayer contamination on adsorbate-induced noise processes. Using exact numerical calculations for H and N atomic monolayers on a Au(111) surface, representing opposite extremes of physisorption and chemisorption, we show that an additional monolayer can significantly affect the noise power spectrum and, respectively, enhance and suppress the heating rates.
Electric-field noise is a major source of motional heating in trapped-ion quantum computation. While the influence of trap-electrode geometries on electric-field noise has been studied in patch potential and surface adsorbate models, only smooth surfaces are accounted for by current theory. The effects of roughness, a ubiquitous feature of surface electrodes, are poorly understood. We investigate its impact on electric-field noise by deriving a rough-surface Green's function and evaluating its effects on adsorbate-surface binding energies. At cryogenic temperatures, heating-rate contributions from adsorbates are predicted to exhibit an exponential sensitivity to local surface curvature, leading to either a large net enhancement or suppression over smooth surfaces. For typical experimental parameters, orders-of-magnitude variations in total heating rates can occur depending on the spatial distribution of adsorbates. Through careful engineering of electrode surface profiles, our results suggests that heating rates can be tuned over orders of magnitudes.
Electric-field noise is a major limiting factor in the performance of ion traps and other quantum devices. Despite intensive research over the past decade, the nature and cause of electric field noise near surfaces is not well understood. This dissertation reports the high- temperature dependence of electric-field noise above an Al-Cu surface using a trapped 40Ca+ ion as a probe.We employ a novel setup with a surface ion trap mounted on a heater for studies of the temperature dependence of electric-field noise. To characterize the Al-Cu material, we explore the effects of heat treatment through ex situ annealing followed by inspection in a scanning electron microscope. To calibrate the temperature of the trap, we demonstrate the use of thermal imaging for monitoring the temperature of an ion trap in vacuum.The temperature and frequency dependence of electric-field noise above the surface is measured using the heating rate of a single ion in a surface-electrode Paul trap. We find that the heating rate saturates at temperatures greater than 450 K. We find that the frequency dependence shows a 1/f behavior, and has a lower frequency scaling exponent at high temperatures than at room temperature. We show that these results are a reflection of the surface-related noise by eliminating other possible sources of noise.Building on historical data for resistance fluctuations in thin films, we develop the thermally-activated fluctuator model to describe the results. We find that a broad distribution of fluctuators with energy barriers peaked around 0.5 eV accurately models both the temperature and frequency dependence of the electric-field noise measured. We present the interpretation of this model as a way to infer that the cause of electric-field noise in the trap is likely defect motion in the metal surface, connecting the problems faced in ion trapping to a large body of work in solid state physics.