University of Glasgow – University News

A major breakthrough in quantum technology research could create a new generation of precise quantum sensors that can operate at room temperature.

The research, led by an international team of researchers from the University of Glasgow, Imperial College London and UNSW Sydney, shows how the quantum states of molecules can be sensitively controlled and detected under ambient conditions.

These results could help unlock a new class of quantum sensors that could be used to probe biological systems, new materials or electronic devices by measuring magnetic fields with high sensitivity and spatial resolution.

By using molecules as quantum sensors, future devices that build on the team’s research could measure magnetic fields down to nanoscales in an easy-to-deploy manner.

In a new paper published in the journal Physical Review Letters, the researchers showed how they could manipulate a specific quantum property called “spin” in organic molecules and measure it with visible light, all at room temperature.

The team used lasers to align the spins of electrons in molecules, which can be thought of as tiny quantum magnets. Using carefully directed pulses of microwave radiation, they were able to control these spin states to achieve the desired quantum states. They were then able to measure the state of the spins using the amount of visible light emitted by the molecules from a second laser pulse, which varies depending on the quantum state of the spins.

In their proof of principle, the team used an organic molecule called pentacene incorporated into two forms of a material called para-terphenyl, both in crystals and in a thin film, which could open up new applications in future devices.

The team showed that they could optically detect quantum coherence (the timescale on which quantum states exist) of molecules down to a microsecond at room temperature, much longer than the time needed to manipulate the states.

The longer quantum states can be maintained, the more information future sensors will be able to collect about their interactions with the properties they measure.

Dr Sam Bayliss, from the James Watt School of Engineering at the University of Glasgow, whose group led the measurements, said: “Quantum sensing offers an exciting opportunity to probe the world around us in new ways and promises to measure quantities such as magnetic and electric fields or temperature in ways that classical systems could not.”

“By showing that we can optically detect quantum coherence in molecules at room temperature, this work provides a proof of principle that the key properties required for room-temperature quantum sensing can be achieved in a system that can be chemically synthesized.”

“We are excited about the opportunities these results could open, from easy-to-apply layers for magnetic resonance imaging on short time scales, to probing biological systems with enhanced sensitivity using quantum technology.”

Dr Max Attwood, from the Department of Materials and Nanotechnology Centre at Imperial College London, who leads the synthesis and materials science in the work, said: “This demonstration is particularly exciting because, unlike inorganic sensors, the molecules can be chemically tuned and deployed in a variety of ways. Future research could improve their quantum properties, target a wider range of sensing applications and use precise placement techniques to efficiently detect targets of interest.”

The team’s paper, titled “Coherent control of molecular spins optically detected at room temperature,” is published in Physical Review Letters. The research was funded by UK Research and Innovation (UKRI), the Engineering and Physical Sciences Research Council (EPSRC), the Australian Research Council and the Sydney Quantum Academy.

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First published: September 17, 2024