[Paper Review] Method for Determination of Technical Noise Contributions to Ion Motional Heating

Jonathon Sedlacek, Jules Stuart+5 more|arXiv (Cornell University)|May 23, 2018

Quantum Information and CryptographyComputer Science19 references17 citations

TL;DR

This paper presents a quantitative method to isolate and measure technical noise contributions from DC and RF electrodes to ion motional heating in surface-electrode Paul traps. By injecting known noise into individual electrodes and measuring resulting heating rates, the authors demonstrate that RF noise dominates heating when ions are displaced from the RF null due to pseudopotential gradients, and that minimizing these gradients significantly reduces heating.

ABSTRACT

Microfabricated Paul ion traps show tremendous promise for large-scale quantum information processing. However, motional heating of ions can have a detrimental effect on the fidelity of quantum logic operations in miniaturized, scalable designs. In many experiments, contributions to ion heating due to technical voltage noise present on the static (DC) and radio frequency (RF) electrodes can be overlooked. We present a reliable method for determining the extent to which motional heating is dominated by residual voltage noise on the DC or RF electrodes. Also, we demonstrate that stray DC electric fields can shift the ion position such that technical noise on the RF electrode can significantly contribute to the motional heating rate. After minimizing the pseudopotential gradient experienced by the ion induced by stray DC electric fields, the motional heating due to RF technical noise can be significantly reduced.

Motivation & Objective

• To systematically determine the extent to which technical voltage noise on DC and RF electrodes contributes to ion motional heating.
• To separate technical noise contributions from other sources of anomalous heating in trapped-ion systems.
• To quantify how stray DC electric fields and pseudopotential gradients amplify RF noise-induced heating.
• To provide a scalable, repeatable experimental technique for identifying and mitigating technical noise in miniaturized ion traps.

Proposed method

• Injects known broadband voltage noise (100 Hz–100 MHz) into individual DC or RF electrodes using a noise source and bias tee.
• Meets the noise injection with a 13-bit DAC and amplifier to maintain signal integrity.
• Measures the resulting increase in ion motional heating rate via sideband spectroscopy and Rabi oscillation decay.
• Uses theoretical models based on voltage noise spectral density and characteristic distances (Di,j) to calculate expected heating rates.
• Compares measured heating increases to theoretical predictions to isolate contributions from DC and RF noise.
• Employs electrostatic boundary element simulations to compute Di,j values, validated by experimental noise injection.

Experimental results

Research questions

• RQ1 To what extent is motional heating in surface-electrode traps dominated by technical noise on DC versus RF electrodes?
• RQ2 How do stray DC electric fields and pseudopotential gradients influence the impact of RF technical noise on heating rates?
• RQ3 Can technical noise contributions be quantitatively separated from other sources of anomalous heating using controlled noise injection?
• RQ4 What is the role of voltage noise spectral density and electrode geometry in determining heating rates?

Key findings

• The method successfully isolates and quantifies technical noise contributions, showing that RF noise dominates heating when ions are displaced from the RF null.
• After minimizing the pseudopotential gradient via DC field compensation, RF technical noise contributed significantly less to heating, demonstrating its mitigation.
• Measured heating rates from injected DC noise matched theoretical predictions based on the first term in Eq. (1), validating the model.
• The Johnson noise from the RF resonator was estimated at ~1×10−17 V²/Hz, but residual experimental noise was >1×10−14 V²/Hz, indicating technical noise dominates.
• Stray DC fields shifted the ion from the RF null, increasing sensitivity to RF noise and thus heating, highlighting the need for gradient minimization.
• The technique enables precise filtering of DC and RF voltage sources to reduce heating while preserving fast shuttling capabilities.