Voltage Noise Thermometry in Integrated Circuits at Millikelvin Temperatures

TL;DR

This paper introduces voltage noise thermometry with cross-correlation as a dissipation-free method for measuring temperature inside CMOS integrated circuits at millikelvin temperatures, showing broad agreement with known temperature ranges and models.

Contribution

It demonstrates a novel, non-invasive thermometry technique suitable for cryogenic ICs, with potential for detailed thermal profiling in quantum computing applications.

Findings

Broad agreement with refrigerator temperature from 300 mK to 8 K

Consistent results with independent in-IC thermometry and thermal models

Feasibility of monitoring local temperatures using multiple resistors

Abstract

This paper demonstrates the use of voltage noise thermometry, with a cross-correlation technique, as a dissipation-free method of thermometry inside a CMOS integrated circuit (IC). We show that this technique exhibits broad agreement with the refrigerator temperature range from 300 mK to 8 K. Furthermore, it shows substantial agreement with both an independent in-IC thermometry technique and a simple thermal model as a function of power dissipation inside the IC. As the device under test (DUT) is a resistor, it is feasible to extend this technique by placing many resistors in an IC to monitor the local temperatures, without increasing IC design complexity. This could lead to better understanding of the thermal profile of ICs at cryogenic temperatures. This has its greatest potential application in quantum computing, where the temperature at the cold classical-quantum boundary must be carefully controlled to maintain qubit performance.