Does a standalone, "cold" (low-thermal-noise), linear resistor exist without cooling?

TL;DR

This paper investigates whether a linear resistor can be designed to have a low noise temperature without cooling, demonstrating a feedback-based system that achieves a noise temperature of about 3 Kelvin, significantly lower than ambient.

Contribution

The authors introduce a novel feedback-based linear resistor design that produces a substantially reduced noise temperature, surpassing previous passive cooling methods.

Findings

Achieved a noise temperature of approximately 3 Kelvin.

Demonstrated a linear resistor with reduced thermal noise using feedback.

Compared the new design with traditional inverting amplifier solutions.

Abstract

Classical ways of cooling require some of these elements: phase transition, compressor, non-linearity, valve, and/or switch. A recent example is the 2018 patent of Linear Technology Corporation; they utilize the shot noise of a diode to produce a standalone nonlinear resistor that has T/2 noise temperature (about 150 Kelvin). While such "resistor" can cool its environment when it is AC coupled to a resistor, the thermally cooling effect is only academically interesting. The importance of the invention is of another nature: In low-noise electronics, it is essential to have resistors with low noise temperature to improve the signal-to-noise ratio. A natural question is raised: can we use a linear system with feedback to cool and, most importantly, to show reduced noise temperature? Exploring this problem, were able to produce standalone linear resistors showing strongly reduced thermal noise. Our must successful test shows T/100 (about 3 Kelvin) noise temperature, as if the resistor would have been immersed in liquid helium. We also found that there is an old solution offering similar results utilizing the virtual ground of an inverting amplifier at negative feedback. There the "cold" resistor is generated at the input of an amplifier. On the other hand, our system generates the "cold" resistance at the output, which can have practical advantages.