Levitating Nano Cluster Could Unlock Dark Matter and Next-Gen Sensors

ETH Zurich scientists have suspended nano glass spheres in mid-air, revealing quantum vibrations previously too small to measure. Their room-temperature feat opens the door to new quantum sensors that could one day detect dark matter or enable GPS-free navigation.

In brief

• Future quantum technologies will need to manipulate not just single atoms but much larger particles with the same precision.
• ETH Zurich scientists have successfully stabilized a comparatively large nanoscale object so well that nearly all its movements are governed by quantum mechanics.
• This breakthrough could pave the way for highly sensitive quantum sensors, opening possibilities for next-generation navigation systems and advanced medical applications.

Levitating Nano Towers for Quantum Breakthroughs

Three tiny glass spheres cling together, forming a delicate vertical cluster that resembles three scoops of ice cream stacked atop one another—only on an unimaginably smaller scale. The cluster’s total width is about one-tenth that of a human hair. Using a combination of laser beams and precision optical instruments, researchers at ETH Zurich managed to keep these minuscule spheres suspended almost perfectly still in midair. This remarkable control could pave the way for the next generation of quantum sensors, which, along with quantum computers, represent some of the most promising technologies emerging from quantum research.

In their levitation experiment, the team led by Martin Frimmer, adjunct professor of photonics, succeeded in counteracting the pull of gravity on the glass spheres. Yet the elongated cluster continued to quiver slightly, much like a compass needle coming to rest. These vibrations were incredibly rapid and subtle: the structure wobbled about one million times per second, with each movement spanning only a few thousandths of a degree. This faint rotational motion reflects a fundamental quantum behavior known as zero-point fluctuation—the tiny, unavoidable movement that all matter experiences.

“According to the principles of quantum mechanics, no object can ever remain perfectly still,” explains Lorenzo Dania, a postdoc in Frimmer’s group and first author of the study. “The larger an object is, the smaller these zero-point fluctuations are and the more difficult it is to observe them.”

Record-Breaking Quantum Purity at Room Temperature

Until now, no one had measured such minute movements in an object of this size with comparable precision. The ETH Zurich team succeeded because they were able to filter out almost all classical, non-quantum sources of motion that would normally obscure the signal. In their measurements, 92 percent of the cluster’s motion could be attributed to quantum effects, leaving only 8 percent from classical physics—a level of “quantum purity” that exceeded expectations. “Beforehand, we didn’t expect to achieve such a high level of quantum purity,” says Dania.

The achievement was even more impressive because it was done at room temperature. Typically, experiments of this kind require cooling equipment that brings samples close to absolute zero (-273 degrees Celsius). ETH’s setup needed no such extreme conditions. Frimmer compares the feat to a leap in efficiency: “It’s like we’ve built a new vehicle that transports more cargo than traditional lorries and at the same time consumes less fuel.”

Quantum Giants in the Nano World

While many researchers investigate quantum effects in individual or small groups of atoms, Frimmer and his group are among those working with relatively large objects. Their nanosphere cluster may be tiny in everyday terms, but it consists of several hundred million atoms, making it enormous from a quantum physicist’s perspective. The interest in objects of this size is partly driven by hopes for future quantum technology applications, for example. Such applications require larger systems to be controlled using the principles of quantum mechanics.

The researchers were able to levitate their nano particles using what is known as an optical tweezer. In this process, the particle is placed in a vacuum in a transparent container. A lens is used to focus polarized laser light at a point inside this container. At this focal point, the particle aligns with the electric field of the polarized laser and thus remains stable.

A Launchpad for Future Quantum Technologies

“What we’ve achieved is a perfect start for further research that one day could feed into applications,” says Frimmer. For such applications, you first need a system with high quantum purity in which all external interference can be successfully suppressed and movements controlled in the manner desired, he states, adding that this has now been achieved. It would then be possible to detect quantum mechanical effects, to measure these and to use the system for quantum technological applications.

Possible applications include basic research in physics to design experiments to investigate the relationship between gravity and quantum mechanics. The development of sensors to measure tiny forces such as those of gas molecules or even elementary particles that act on the sensor is also conceivable. This would be useful in the search for dark matter. “We now have a system that is relatively simple, cost-effective and well-suited for this purpose,” says Frimmer.

Medical Imaging and GPS-Free Navigation

In the distant future, quantum sensors could also be used in medical imaging. It is hoped that they will be able to detect weak signals in environments where measuring devices otherwise mainly pick up background noise. Another potential application could be motion sensors that could facilitate vehicle navigation even when there is no contact with a GPS satellite.

For the majority of these applications, the quantum system would need to be miniaturized. According to the ETH researchers, this is possible in principle. In any case, they have found a way to achieve the desired controllable quantum state without time-consuming, costly and energy-intensive cooling.

Explore Further: Room-Temperature Quantum Breakthrough Stuns Physicists

Reference: “High-purity quantum optomechanics at room temperature” by Lorenzo Dania, Oscar Schmitt Kremer, Johannes Piotrowski, Davide Candoli, Jayadev Vijayan, Oriol Romero-Isart, Carlos Gonzalez-Ballestero, Lukas Novotny and Martin Frimmer, 6 August 2025, Nature Physics.
DOI: 10.1038/s41567-025-02976-9

The ETH Zurich researchers carried out this work together with colleagues from the Vienna University of Technology, the University of Manchester and the Institut de Ciències Fotòniques in Barcelona.

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