Researchers at the Okinawa Institute of Science and Technology in Japan have, for the first time, observed a mechanical displacement of a centimeter-scale object driven by the quantum spin of electrons, as ScienceAlert reported.
The Diamagnetic Levitation Apparatus
The experimental apparatus relies on a centimeter-sized graphite plate suspended above a checkerboard arrangement of magnets via diamagnetic levitation. Hanging beneath this plate is a 3-millimeter diamond containing specific atomic defects known as nitrogen-vacancy (NV) centers. These defects provide electrons with controllable spins.
To convert quantum-scale phenomena into physical motion, researchers periodically illuminated the diamond with a green laser. This light polarizes the NV centers into a predefined spin state, generating tiny magnetic fluctuations that push the diamond downward. Another magnet translates this spin effect into macroscopic movement. Diamagnetic levitation exploits the weak repulsion between certain materials and magnetic fields, allowing stable suspension without requiring cryogenics or vacuum traps.
Bridging Microscopic Spin and Macroscopic Mass
The entire assembly weighed about 128 milligrams—roughly equivalent to a few grains of rice—and shifted by about 100 nanometers, which measures about one-thousandth of the thickness of a human hair. While the resulting movement is classical, the force triggering it stems directly from a quantum effect.
Theoretical physicist Jason Twamley pointed out that the object in this experiment was eight to nine orders of magnitude more massive than objects utilized in previous spin-mechanical experiments. This leap bridges a critical gap between the very small scale of quantum mechanics and the classical world governed by gravity.
Reversing the Approach to Gravity
Physicist Anshuman Nayak explained that the research team adopted an approach going from large to small, applying diamagnetic levitation to lift centimeter-wide objects holding diamonds where gravity’s effect is extremely strong.
Nitrogen-vacancy centers in diamonds are uniquely suited for this level of investigation because they possess some of the longest known coherence times. As physicist Daehee Kim detailed, these centers can maintain quantum superposition at room temperature much longer than many other systems, making them attractive for generating macroscopic superposition in future research.
Publishing Results and Future Physics
UA.News reported that the study results were published in the journal Science Advances. Looking ahead, the research team aims to refine experimental conditions to place larger objects into quantum states like superposition.
