Quantum heat circuits learn electronics' oldest trick: Sharing a power supply
Every electronic and optoelectronic device generates heat, and today that heat is managed almost entirely from the outside. Heatsinks, fans, cold plates and refrigerators are bulky exterior measures bolted onto a chip or package after the fact. They treat heat as a single averaged quantity to be removed in bulk, even though the heat is actually produced locally, component by component, deep inside the circuitry.
Why do electronics need a new way to handle heat?
Quantum thermal devices offer a fundamentally different approach. Because they are tiny, heat-management circuitry can, in principle, be built right next to each electronic or optoelectronic component that needs it.
Instead of one bulk, averaged solution for an entire chip, each component could have its own tailored thermal circuit beside it, steering heat away exactly where it arises. That is the long-term technological promise motivating this field.
Can we build heat circuits like electronic circuits?
Quantum heat circuits are an emerging approach to controlling energy flow at the quantum scale. This field, also known as quantum thermotronics, borrows ideas from electronics to understand how heat can be controlled in nanoscale systems.
Researchers have proposed thermal versions of familiar electronic devices, including quantum thermal diodes and transistors. More complex arrangements, such as Darlington pairs and logic circuits, have also been explored. The broader goal is to develop heat circuits that can be designed and analyzed using engineering principles, much like electronic circuits.
What is new in our work?
Our paper, published in the journal Physical Review B, makes two advances that bring this goal much closer.
Until now, quantum thermal transistors, which can switch and amplify heat flow, had no equivalent arrangement. In existing models, each terminal of every thermal transistor typically needs its own heat reservoir, so a circuit containing N transistors could require 3N reservoirs. As circuits grow, the number of required reservoirs grows just as fast, making large thermal circuits impractical to build and control.
Our work removes this roadblock by introducing quantum thermal links that allow many transistors to share a small number of reservoirs. These links play a role similar to the biasing and impedance networks of electronic circuits. They distribute thermal energy through the network while keeping every transistor at its correct operating point.
Second, we derive thermal counterparts of Kirchhoff's current and voltage laws for these circuits in the small-signal regime. These laws give engineers a systematic, familiar way to analyze networks of quantum thermal devices, writing down and solving thermal circuit equations much as one analyzes a traditional electronic circuit, without solving the full quantum dynamics every time.
Together with shared-reservoir biasing, this builds a working bridge between quantum heat circuits and classical circuit theory.
What comes next?
With biasing and circuit laws in place, the path ahead looks much like the early history of electronics itself. The transistor came first, then circuit theory, and only then the integration that changed the world.
Quantum thermotronics now has its circuit theory, and the next steps are those any young technology needs to take. That is, to identify the best material platforms for building thermal transistors that operate at the temperatures where real electronic and optoelectronic devices operate and to determine how to integrate them beside the components whose heat they will manage.
The prize is considerable because heat is the one problem every future chip is guaranteed to have, and a technology that manages it locally, device by device, has a natural place in everything from processors to lasers to sensors.
The remaining questions are as much an opportunity as a challenge, and they are exactly the kind that attract fresh minds into a field. How should temperature be defined and controlled in very small systems? And how far can simple engineering rules, like the thermal circuit laws derived here, carry the design of complex heat circuits without solving the full quantum dynamics every time? Each answer will bring tailored, component-level heat management a step closer to practice.
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Publication details
Uthpala N. Ekanayake et al, Towards quantum thermotronic circuits: A biasing scheme for quantum thermal transistors with quantum thermal links, Physical Review B (2026). DOI: 10.1103/pvr5-s5z5
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Dr. Uthpala Ekanayake, MIEE, MIEAust, is a Research Fellow at Monash University specializing in quantum device engineering. Her research focuses on quantum thermal transistors, nanoscale heat transport, noise, and feedback control. Her doctoral research received the Douglas Lampard Electrical Engineering Research Commendation Award from Monash University.
Prof. Malin Premaratne, FIEEE, FOptica, FSPIE, FInstP, FIET, FIEAust, is a Professor at Monash University and a leading authority in quantum optics, quantum device theory, and quantum engineering. His research spans quantum electrodynamics, photonics, and advanced quantum devices, with contributions to lasers, optical amplifiers, spasers, and transistors. He has authored more than 300 journal publications and two books and secured over $10 million in competitive research funding. He is also a member of the Australian Research Council College of Experts.
Citation: Quantum heat circuits learn electronics' oldest trick: Sharing a power supply (2026, August 10) retrieved 10 August 2026 from https://phys.org/news/2026-08-quantum-circuits-electronics-oldest-power.html
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