Reviewed by Danielle Ellis, B.Sc.Sep 18 2024
A new study published in the journal Physical Review Letters, conducted by an international team of researchers from the University of Glasgow, Imperial College London, and UNSW Sydney, demonstrates how the quantum states of molecules can be regulated and identified under ambient conditions.
Image Credit: University of Glasgow
A breakthrough in quantum technology research could pave the way for a new generation of precise quantum sensors capable of operating at room temperature.
The findings could pave the way for a new class of quantum sensors capable of probing biological systems, novel materials, or electronic devices using magnetic fields with high sensitivity and spatial resolution.
The team's research, which utilizes molecules as quantum sensors, could pave the way for future devices that measure magnetic fields at convenient nanometer-length scales.
In the study, scientists demonstrated how to control an organic molecule’s “spin,” a particular quantum property, and measure it at room temperature using visible light.
The team used lasers to align the electron spins in the molecules—which are essentially tiny quantum-mechanical magnets. They could manipulate these spin states into the desired quantum states by applying precisely targeted microwave radiation pulses. The amount of visible light emitted from the molecules during a second laser pulse could then be used to determine the spins' state because it varies based on the quantum state of the spins.
The researchers employed an organic molecule known as pentacene in two different forms of a material known as para-terphenyl—both in crystals and a thin film—in their proof-of-principle demonstration, which may lead to new uses in devices in the future.
The group demonstrated that, at room temperature, they could optically detect the molecules’ quantum coherence—the duration over which quantum states exist—for up to a microsecond, which is far longer than the time required to manipulate the states.
Future sensors could gather more data about how long quantum states can be maintained and how those states interact with the properties they are measuring.
Quantum sensing offers an exciting opportunity to probe the world around us in new ways, and holds promise to measure quantities such as magnetic and electric fields or temperature in ways which 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 needed for room-temperature quantum sensing can be achieved in a system which can be chemically synthesized.
Dr. Sam Bayliss, Lecturer, James Watt School of Engineering, University of Glasgow
He added, “We are excited by the opportunities these results could open up, from easy-to-apply layers for magnetic resonance imaging over short length scales, to probing biological systems with quantum-enhanced sensitivity.”
Dr. Max Attwood, of Imperial College London’s Department of Materials and London Centre for Nanotechnology, who led the synthesis and materials science in this study further added, “This demonstration is particularly exciting because, unlike inorganic sensors, molecules can be chemically tuned and deployed in various ways. Future research could enhance their quantum properties, target a wider range of sensing applications, and employ precise placement techniques to effectively sense targets of interest.”
This study was funded by the Australian Research Council, the Sydney Quantum Academy, the Engineering and Physical Sciences Research Council (EPSRC), and UK Research and Innovation (UKRI).
Journal Reference:
Mena, A., et. al. (2024) Room-Temperature Optically Detected Coherent Control of Molecular Spins. Physical Review Letters. doi.org/10.1103/PhysRevLett.133.120801