Towards in-situ cleaning of a trapped ion quantum computer

TL;DR

This paper demonstrates a simple plasma cleaning system using a microwave oven to effectively remove surface contaminants from ion trap electrodes, potentially improving their performance and longevity in quantum computers.

Contribution

It introduces a low-cost, in-situ plasma cleaning method for ion trap electrodes, showing its effectiveness in removing various contaminants and enhancing optical cavity finesse.

Findings

Argon plasma removes copper oxide in 1-2 minutes

Air addition enables removal of hydrocarbons like permanent marker

Surface removal rate of 5-15 nm per minute

Abstract

A plasma glow discharge system was created using a conventional microwave oven to ignite and maintain the plasma. The system was used for plasma cleaning and its properties were analysed to assess its viability for removing surface contaminants, which cause anomalous heating, from Paul trap electrodes used in ion trapping. Qualitative results showed that the argon plasma could remove copper oxide layers formed on thin sheets in 1-2 minutes. The addition of air into the plasma system allowed for the cleaning of more complex hydrocarbon contaminants, as highlighted by the removal of permanent marker pen. The surface removal rate of the system was evaluated by measuring the time taken to remove gold plating from washers and aluminium plates. A nominal rate of 5-15 nm per min was found under optimal conditions. Plasma treatment, in addition to wet chemical cleaning, was found to increase the finesse of an optical cavity by a factor of two, compared to acetone cleaning alone. These results are promising for the system's in-situ use on Paul trap electrodes and could be a feasible technique for increasing their lifetime.