For the first time, scientists have demonstrated a unique quantum effect that can move a centimeter-scale object “levitated” against gravity, a groundbreaking achievement that could assist in future studies of the boundary between quantum mechanics and classical physics.
A recent study published in Science Advances showcases the work of a team at the Okinawa Institute of Science and Technology (OIST), which used the quantum spin of electrons to produce enough force to move a levitating diamond.
The achievement could pave the way toward new methods of studying gravity, and also could lead to the development of some of the world’s most sensitive quantum sensing technologies.
Levitating Diamonds to Unveil Quantum Phenomena
While strange effects of quantum mechanics are responsible for the behavior of atoms and subatomic particles, a longstanding problem for physicists involves observing its effects on larger objects.
With their susceptibility to the effects of environmental disturbances that include vibrations and heat, such objects are capable of quickly overpowering the otherwise delicate effects of the quantum variety.
While overcoming these problems presents its own unique challenges, OIST researchers developed an experimental apparatus featuring a diamond packed with billions of nitrogen-vacancy centers—atomic defects that trap electrons whose quantum spin can be controlled using light.
Suspended above a magnet and connected to a levitating graphite plate by a carbon-fiber rod, the diamond was illuminated with pulses of green laser light. This allowed the researchers to control the spin states of electrons trapped within the diamond, generating tiny magnetic forces that caused it to move.
The movements the research team observed were then measured with picometer precision, made possible using an extremely sensitive laser interferometer.
“We’ve shown a large classical response from a small quantum effect,” said OIST Professor Jason Twamley in a statement.
Driving Mechanical Motion with Quantum Spin
The team emphasized that while their experiment has not demonstrated quantum superposition in a macroscopic object, it does establish that quantum spin can generate measurable mechanical motion in an object that is far larger than those used in past quantum experiments.
In the future, refinements to this process could help researchers explore the possibility that larger objects can indeed exist in states of quantum superposition—an achievement that would provide deeper insights into the relationship between gravity and the phenomena observed in quantum mechanics.
Fundamentally, the researchers also believe their findings contribute to the development of extraordinarily sensitive instruments that could be capable of detecting elusive phenomena such as gravitational waves, dark matter, and others that have long perplexed scientists.
“We’ve shown a large classical response from a small quantum effect. It’s no longer a question of whether such technology is possible, but of how we can refine experimental conditions to achieve quantum superposition within the regime of Einstein’s general relativity,” Twamley said in a statement.
“And on the way, we’re developing a new class of extremely precise sensors. We’re pushing the bar from nanometers to centimeters.”
“All we need is another order of magnitude,” Twamley adds, “and we can finally observe Schrödinger’s cat in real life.”
The research team’s findings were detailed in a recent paper, “Spin force from a nitrogen-vacancy ensemble drives a 100-mg levitated resonator,” published in Science Advances.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.