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At first glance, biology and quantum technology seem incompatible. Living systems operate in warm, noisy environments full of constant motion, while quantum technology typically requires extreme isolation and temperatures near absolute zero to function.

But quantum mechanics is the foundation of everything, including in biological molecules. Now, researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) have turned a protein found in living cells into a functioning quantum bit (qubit), the foundation of quantum technologies. The protein qubit can be used as a quantum sensor capable of detecting minute changes and ultimately offering unprecedented insight into biological processes.

"Rather than taking a conventional quantum sensor and trying to camouflage it to enter a biological system, we wanted to explore the idea of using a biological system itself and developing it into a qubit," said David Awschalom, co-principal investigator of the project, Liew Family Professor of Molecular Engineering at UChicago PME and director of the Chicago Quantum Exchange (CQE). "Harnessing nature to create powerful families of quantum sensors—that's the new direction here."

The interdisciplinary advance is in Nature.

Unlike engineered nanomaterials, protein-qubits can be built directly by cells, positioned with atomic precision, and detect signals thousands of times stronger than existing quantum sensors. Looking ahead, these protein-qubits could drive a revolution in quantum-enabled nanoscale MRI, revealing the atomic structure of the cellular machinery and transforming our way of performing biological research. Beyond biology, protein qubits could also open new frontiers for advancing quantum technology itself.

"Our findings not only enable new ways for quantum sensing inside living systems but also introduce a radically different approach to designing quantum materials," said Peter Maurer, co-principal investigator and assistant professor of molecular engineering at UChicago. "Specifically, we can now start using nature's own tools of evolution and self-assembly to overcome some of the roadblocks faced by current spin-based quantum technology."

Genetically encoded fluorescent proteins like the one used in this study have become a crucial tool in cell biology over the past two decades, allowing scientists to study processes that take place within a cell. Turning one of these proteins into a quantum sensor enables research into biological systems at an even deeper, more precise level. And though this research only used one kind of fluorescent protein, the researchers say it should work broadly across wide classes of proteins and systems, opening up myriad possibilities for future study.

"This is a really exciting shift," said co-first author Benjamin Soloway, a UChicago PME quantum Ph.D. candidate in Awschalom's lab. "Through fluorescence microscopy, scientists can see biological processes but must infer what's happening on the nanoscale. Now, for the first time, we can directly measure quantum properties inside living systems."

Awschalom and Maurer emphasized that the tenacity of the students on the team was vital to the success of the project.

"Research projects often take multiple years, and the outcomes are far from certain. This project was no exception," said Jacob Feder, a co-first author on the paper and former student of Awschalom and Maurer. Feder received his Ph.D. in April.

"This work was only possible because our students had the courage to take risks and push forward even when the results looked discouraging for quite some time," Awschalom said. "Their persistence is what made this discovery successful—this was a challenging project."

The new protein-based qubits don't yet rival the sensitivity of today's best quantum sensors, usually made from defects in diamond. But because they can be genetically encoded into living systems, they promise something far more radical: the ability to watch biology unfold at the quantum level, from protein folding and enzyme activity to the earliest signs of disease.

As Soloway put it, "We're entering an era where the boundary between quantum physics and biology begins to dissolve. That's where the really transformative science will happen."