Scientists Built the First Engine Powered by Entanglement—Not Coal or Oil

• Scientists at the Chinese Academy of Sciences have developed a quantum engine powered by entanglement—the quantum property allows for the transfer of information across vast distances.

• The researchers created this engine by placing two calcium atoms in an ion trap, zapping it with a laser, and using the differences in entanglement (rather than heat) to create energy.

• This concept doesn’t improve on the conversion efficiency of previous quantum engines, but it does prove that increased entanglement positively impacts mechanical efficiency.

The word “quantum” is proliferating into nearly every facet of modern technology. There’s quantum computers, of course, but also quantum hard drives, quantum internet, and yes, even quantum engines. However—as is true with all of these other “quantum” technologies—this isn’t your typical piston/combustion situation. Instead, these engines leverage the wonky properties of quantum mechanics to induce mechanical motion.

Although an incredibly nascent technology, quantum engines come in a couple different flavors. Last year, scientists at the Okinawa Institute of Science and Technology developed a quantum engine that leveraged the complicated interplay between fermions and Bose-Einstein condensates. This created energy by replacing heat (the typical energy source of an ICE engine) with the “quantum nature of the particles in the gas,” a press statement read at the time. This engine had an efficiency of 25 percent—not bad for a first go at it, but nowhere close to becoming a practical engine.

Now, scientists from the Chinese Academy of Sciences have developed another method from creating a quantum engine by leveraging another kind of quantum quirk: entanglement. The poster child for all things “quantum,” entanglement is the state that occurs when two particles are in superposition, meaning that their information is inextricably linked—no matter the distance between them. The study used calcium atoms in an ion trap, and at its most basic, the engine harnessed a thermodynamic process that occurs when particles transition from initial to highly entangled states. The results of this study were published in the journal Physical Review Letters.

“Our study’s highlight is the first experimental realization of a quantum engine with entangled characteristics,” Zhou Fei, a co-author of the study, told the state-sponsored media outlet South China Morning Post. “[It] quantitatively verified that entanglement can serve as a type of ‘fuel.’”

The website IFLScience describes the process as being similar to a four-stroke engine. First, the atoms absorb photons from a red laser. Then they expand, are coupled with a quantum load, and compress.

“We chose the entangled states of two spinning ions as the working substance, with [their] vibrational modes acting as the load. Through precise adjustments of laser frequency, amplitude, and duration, the ions were transitioned from their initial pure states to highly entangled states,” Zhou told the South China Morning Post.

This new method didn’t improve upon previous quantum engines’ conversion efficiency, but the study proved that entanglement can generate useful energy. The team analyzed more than 10,000 experiments using calcium ions and found that increased levels of entanglement created improved mechanical efficiency.

Like quantum computers, these “engines” powered by entanglement only operate at temperatures approaching absolute zero. But further research could make these engines and batteries capable of powering expansive quantum computers and circuits. Only time will tell.

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