Printed Circuit Board Metal Powder Filters for Low Electron Temperatures

TL;DR

This paper characterizes printed circuit board metal powder filters and demonstrates their effectiveness in achieving ultra-low electron temperatures in quantum devices, offering a simpler fabrication method with comparable or superior performance.

Contribution

It introduces PCB-based metal powder filters that are easier to produce and perform as well or better than traditional filters in low-temperature quantum experiments.

Findings

Attenuation exceeds 80 dB above 1.5 GHz for stainless steel powder filters.

Attenuation increases with temperature across all metal powders.

Copper powder PCB filters match or outperform classical powder filters.

Abstract

We report the characterisation of printed circuit boards (PCB) metal powder filters and their influence on the effective electron temperature which is as low as 22 mK for a quantum dot in a silicon MOSFET structure in a dilution refrigerator. We investigate the attenuation behaviour (10 MHz- 20 GHz) of filter made of four metal powders with a grain size below 50 um. The room-temperature attenuation of a stainless steel powder filter is more than 80 dB at frequencies above 1.5 GHz. In all metal powder filters the attenuation increases with temperature. Compared to classical powder filters, the design presented here is much less laborious to fabricate and specifically the copper powder PCB-filters deliver an equal or even better performance than their classical counterparts.