These Levitating Nanodiamonds Are the World’s Smallest Disco Balls

Somewhere in the quantum realm, a teeny, tiny rave is afoot. Researchers created ultra-small levitating diamonds, with diameters the size of 350 strands of human DNA, that reflect light like a disco ball as they spin over a billion times per minute.

The itty bitty party decorations are the creation of Purdue University scientists, who are using them to make super-precise measurements that could help illuminate the relationship between quantum mechanics and gravity. There have been previous efforts to levitate nanodiamonds, but actually getting it to work requires incredibly exact conditions.

“In the past, experiments with these floating diamonds had trouble in preventing their loss in vacuum and reading out the spin qubits,” said Tongcang Li, a physics and astronomy professor at Purdue, in a statement. “However, in our work, we successfully levitated a diamond in a high vacuum using a special ion trap. For the first time, we could observe and control the behavior of the spin qubits inside the levitated diamond in high vacuum.”

Qubits, the quantum versions of computer bits, are the fundamental unit of quantum information, where semiconducting material is used to trap individual electron charges and their associated spin. To create the conditions necessary to study how the diamond’s rotation affected the spin qubits, the researchers had to spin the diamond at the dizzying speed of 1.2 billion rotations per minute.

They were able to do this by creating a sapphire wafer with a 300 nanometer-thick gold plating, using photolithography, the same technique used to make computer chips. The diamonds themselves, which measured an average of 750 nanometers in diameter, were created using intense pressure and high temperatures, speeding up the natural process that gives us the sparkly rocks. The diamonds contained tiny structures that could host the electron spin qubits.

To measure a diamond’s spin, it was hit with a green laser, causing it to emit red light. That light, in turn, allowed the researchers to determine the electrons’ spin states. Another laser was used to monitor the nanodiamond’s rotation. As it rotated, the nanodiamond would scatter the lasers’ infrared light, much like a disco ball.

While the new technique, described in a paper in the journal Nature Communications, will allow the study of heady concepts like quantum physics, the researchers said there are practical applications as well, such as using it for precise accelerometers and electric field sensors.

Unfortunately, there was no word on whether the team was also able to invent teeny tiny glow sticks.