Breakthrough in quantum technology could enable precise sensing at room temperature

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

Research carried out by an international team of scientists from the University of Glasgow, Imperial College London and UNSW Sydney shows how the quantum states of molecules can be controlled and detected with high sensitivity under normal conditions.

These findings could lead to the discovery of a new class of quantum sensors that could be used to study 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 based on the team’s research will be able to measure magnetic fields on the nanometer scale in a way that is convenient to implement.

In an article titled “Room-temperature optically detected coherent control of molecular spins” published in the journal Physical inspection lettersScientists have shown how they can manipulate a specific quantum property known as “spin” in organic molecules and measure it using visible light, all at room temperature.

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

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

The team showed they could optically detect quantum coherence — the timescale over which quantum states exist — of molecules for periods 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 sensors offer an exciting opportunity to explore the world around us in new ways and hold out the promise of being able to measure quantities such as magnetic and electric fields or temperature in ways that classical systems could not.”

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

“We are excited about the possibilities these results could open up, from easy-to-use layers for magnetic resonance imaging at short length scales to probing biological systems with quantum-enhanced sensitivity.”

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