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Diamonds that levitate and spin at unimaginable speeds are not merely products of science fiction. They now represent a bold advancement in studying the foundations of the universe. In a groundbreaking experiment, researchers have successfully levitated tiny diamonds in a vacuum and spun them at speeds reaching 1.2 billion rotations per minute. These rotating diamonds are not just a visual spectacle; they help scientists explore the strange rules of quantum physics and how they might connect with gravity.
Diamonds That Float and Spin in a Vacuum
In a vacuum chamber, nanodiamonds approximately 750 nanometers wide were made to levitate using a specially designed ion trap. These diamonds were created through high-pressure, high-temperature processes and then treated with high-energy electrons to form what are known as nitrogen vacancy (NV) centers. These NV centers contain electron spins that can be used as tiny compasses to detect magnetic fields.
The research team developed a special trap to levitate these diamonds and control their spins. This system includes a transmission line shaped like an Ω and an array of electrodes to apply electric fields. This configuration traps the diamond, induces its rotation, and allows scientists to use lasers to read the spin state. For the first time, optical detection of magnetic resonance was achieved on a levitated nanodiamond in a vacuum, said Tongcang Li, one of the lead researchers.
How Light and Rotation Reveal the Quantum World
A green laser shines on each nanodiamond, causing them to glow red and revealing their spin state. Meanwhile, an infrared laser bounces off the rotating diamond, allowing scientists to monitor its speed and direction of rotation. The light scatters like the rays from a spinning disco ball, illuminating its motion.
The team was able to spin these diamonds at a rate of 20 megahertz, equivalent to approximately 1.2 billion rotations per minute. This speed is over a thousand times faster than what the best mechanical systems have achieved with similar materials. It’s not just about spectacular speed; it also helps push quantum spins into new territory where strange behaviors emerge, such as Berry’s phase, a quantum effect that alters the spin’s response as the diamond rotates.
Why This Work Matters for Science and Technology
Levitate particles in a vacuum are special because they are isolated from most external disturbances. With little air or heat to interfere, scientists can isolate and control them with incredible precision. This makes levitated systems ideal for testing fundamental theories and for precision measurement tools like gyroscopes and field sensors.
Levitated nanodiamonds with spin qubits are particularly powerful. They combine the isolation of floating particles with the sharp detection capabilities of quantum spins. This could lead to rotating matter-wave interferometers, new types of accelerometers, and highly sensitive electric field detectors. Recent successes allow for stable levitation at pressures below 10⁻⁵ Torr while controlling and reading spin states.
A Platform for Testing Quantum Gravity
Theories of quantum gravity aim to combine Einstein’s general relativity with the strange rules of quantum mechanics. So far, scientists have not found experimental evidence of such a union. This is where rotating diamonds could help.
By placing quantum bits inside rotating objects, physicists can observe how gravity might affect these spins. The idea is to build large-scale quantum superpositions, states where particles exist in multiple places or configurations simultaneously. If these superpositions can be achieved, they could test whether gravity follows the rules of quantum mechanics. Spinning diamonds are thus not just fascinating tools; they are potential bridges between two major scientific theories.
The technical and scientific advancements made with rotating diamonds are impressive. But what will be the next step in the quest to understand how gravity connects with quantum phenomena?
