Noise‑Driven Cooling for Quantum Computers * Science and Technology Times

Researchers in Sweden have developed a quantum refrigerator that uses noise to cool quantum circuits instead of trying to eliminate it.
Their device offers precise control over heat flow at extremely small scales, addressing one of the biggest challenges in scaling quantum computers.
The approach could open new paths toward more stable and energy‑efficient quantum technologies.

Turning a fundamental problem into a cooling method

Quantum computers require temperatures near absolute zero to maintain the fragile states that allow qubits to function. Traditional cooling systems achieve these temperatures but also introduce noise that can disrupt quantum information. A team at Chalmers University of Technology has now demonstrated a device that uses controlled noise as a tool rather than treating it as an obstacle. Their quantum refrigerator relies on noise to drive heat transport with remarkable precision.

The researchers describe their system as a minimal refrigerator built directly into quantum circuits. It operates by steering heat between two microwave channels that act as hot and cold reservoirs. These reservoirs are connected to an artificial molecule composed of two superconducting qubits. Controlled microwave noise injected through a third port enables and regulates the heat flow between them.

This approach allows the device to function not only as a refrigerator but also as a heat engine or an energy amplifier. The versatility comes from the ability to adjust reservoir temperatures and noise characteristics. Such fine‑grained control is essential for managing heat in increasingly complex quantum processors. It also demonstrates how noise, typically seen as a threat to quantum coherence, can be repurposed as a functional resource.

Why extreme cold is essential for quantum systems

Superconducting quantum computers must operate at temperatures close to –273 °C to maintain stable quantum states. At these temperatures, materials become superconducting, allowing electrons to move without resistance. Only under such conditions can qubits store and manipulate quantum information reliably. Even slight temperature fluctuations or electromagnetic interference can destroy these states.

The sensitivity of qubits makes heat management one of the most difficult engineering challenges in quantum computing. As systems grow larger, unwanted energy spreads more easily and becomes harder to control. Researchers must therefore understand how heat moves through quantum circuits at extremely small scales. This knowledge is crucial for designing devices that remain stable as they increase in size and complexity.

Simon Sundelin, the study’s lead author, emphasized the importance of tracking how energy is transported and dissipated. He noted that predictable and controllable heat flows are essential for building scalable quantum systems. His team’s work demonstrates that even tiny heat currents can be measured and manipulated. These measurements reached the attowatt range, illustrating the precision required for quantum thermal engineering.

Noise‑powered refrigeration and future applications

The Chalmers team’s device is based on a concept known as Brownian refrigeration, where random thermal fluctuations are harnessed to produce cooling. Physicists have long theorized about such systems, but practical implementations have been limited. The artificial molecule at the heart of the device behaves like a natural molecule but is built from superconducting circuits. This structure allows researchers to guide heat flow using carefully tuned microwave noise.

By injecting noise within a narrow frequency range, the team can activate or suppress heat transport between the reservoirs. The resulting control over energy flow enables the device to operate in multiple modes depending on the experimental setup. This flexibility is particularly valuable for quantum processors, where heat is generated locally during qubit operations. Managing that heat directly inside the circuit could improve performance in ways traditional cooling systems cannot.

Aamir Ali, a co‑author of the study, highlighted the importance of controlling heat at scales unreachable by conventional methods. He noted that the ability to remove or redirect heat inside quantum circuits could lead to more reliable quantum technologies. Such advances are essential for building larger systems capable of solving real‑world problems. The work therefore represents a step toward practical quantum computing.