Researchers have observed unusual patterns of heat flow inside quantum computers, revealing behaviors that defy classical thermodynamics. The work, led by Professor Aabhaas Vineet Mallik of Bar-Ilan University in Israel and BITS Pilani K K Birla Goa Campus in India, highlights how a technique known as mid-circuit measurement could deepen our understanding of quantum mechanics while helping to build more reliable quantum machines.
Gate-based quantum computers promise universal application
Unlike ordinary computers, which use transistors to store information as ones and zeros, quantum computers rely on qubits, that can exist in a blend of both states at once. These fragile quantum states allow qubits to hold and process information in ways impossible for classical bits. One major approach is known as gate-based quantum computing, where operations are applied step by step through discrete “gates” that guide the evolution of the qubits.
Other types of quantum computers, such as those developed by D-Wave, rely on a different strategy in which a quantum system evolves continuously toward a solution. While such devices can be powerful for optimization problems, their scope is limited. By contrast, Mallik says, gate-based machines “are in principle universal, meaning they can be used to solve any computational problem and can be integrated with digital computers more readily.”
This universality is why companies like IBM, Google, and Microsoft are investing heavily in gate-based designs. In the long term, they could be used to simulate exotic materials, design new medicines, or predict how proteins fold — tasks far beyond the reach of even the fastest supercomputers.
Measuring in the middle of a quantum process
One of the major challenges in quantum computing is error. Every step of a quantum algorithm introduces tiny deviations that can build up and overwhelm the final result. In quantum mechanics, however, measurement is not passive — it disturbs the system and forces a qubit’s uncertain state into a definite outcome. This peculiarity makes measuring qubits tricky, but also powerful.
A promising method for addressing errors involves checking their states not just at the end of a computation, but also during it, a strategy known as mid-circuit measurement.
Such checks can help keep errors from spiraling out of control. But they can also play another, more surprising role: offering a window into the laws of quantum thermodynamics. In their new study, Mallik and his colleagues tested mid-circuit measurements as a way to probe how heat behaves in quantum systems.
Observing anomalous quantum heat flow
Heat behaves predictably in our everyday world, but quantum physics often challenges such expectations. “In the simplest sense, a heat flow is anomalous when it does not follow the law of classical thermodynamics, which says that heat always flows from the hotter body to the colder body,” Mallik explained.
Under certain conditions, heat can appear to flow against the gradient, and the explanation lies in quantum correlations. These are subtle connections between systems that cannot be explained by classical physics. Mallik and his team found that, with the right design, mid-circuit measurements can make these elusive effects visible.
“We have been able to identify a class of quantum computer architectures where the error due to mid-circuit measurements is small enough for an unambiguous observation of something called an anomalous quantum heat flow,” he said.
The group not only observed cases where heat flowed in seemingly the “wrong” direction, but also detected conventional hot-to-cold flows that still arose from purely quantum correlations. “In our study we unambiguously observe instances of such non-classical heat flow also referred to as quantum anomalous heat flow,” Mallik noted.
Why thermodynamics matters for building quantum computers
Although these results probe fundamental physics, they also have practical significance. Every quantum computer is subject to noise and error, and understanding how measurement itself introduces disturbance is crucial for making them robust.
“The characterization of noise due to mid-circuit measurement is technologically important for a robust realization of a quantum computer,” Mallik said. He added that while private companies are likely studying this problem internally, “ours is one of the very few papers in the public domain which attempts to address this question.”
That means academic groups and public agencies can immediately benefit from the team’s results, especially those working with superconducting quantum technologies, the most widely used platform today.
Beyond error correction, the work also points to a new use of quantum thermodynamics as a kind of benchmark: by testing whether a computer exhibits anomalous heat flows, researchers may gain a direct way to verify how “quantum” a machine truly is. “This may see further development and use in near future,” Mallik said.
Developing new protocols to test quantum computers
The findings open several avenues for further exploration. Mallik and his collaborators plan to extend their methods to larger systems and compare different types of quantum hardware. “A few directions which might be worth exploring are developing more quantum thermodynamics-based protocols to ascertain the quantumness of a quantum computer, implementing a similar protocol on different architectures, and developing protocols to characterize the noise due to mid-circuit measurements in greater detail,” he said.
As quantum computing advances, researchers face a dual challenge: taming errors while also grappling with the strange rules of the quantum world. This new study shows that the two problems are linked. By using mid-circuit measurements not just as a practical tool but as a probe of quantum physics itself, scientists are learning how to both test and improve the machines of the future.
Reference: A. V. Mallik et al., Probing Quantum Anomalous Heat Flow Using Mid‐Circuit Measurements, Advanced Quantum Technologies (2025), DOI: 10.1002/qute.202500328
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