To us living our lives on the macroscale, the tiny world of quantum mechanics seems weird and nonsensical. Take, for instance, quantum entanglement – the idea that two objects can become so entwined that changes to one can instantly affect the other, no matter how far apart they are. This has been regularly proven to be possible with atoms and molecules, but now scientists have managed to demonstrate it on a much larger scale, which is beginning to cross over into our everyday world.
Although entanglement was implied by his own calculations of quantum mechanics, Albert Einstein famously recoiled from the idea, insisting that there must be another hidden explanation that didn't require resorting to "spooky action at a distance." About 80 years on, though, quantum entanglement has been experimentally observed time and time again, and forms the foundation for emerging technologies like quantum computing, encryption and teleportation.
But the phenomenon has still been confined to the microscopic scale. Now, an international team of scientists has successfully entangled objects that are much larger – almost visible to the naked eye – which is a key step towards making more practical use of it. Even better, the researchers managed to hold these objects in their entangled state for up to 30 minutes, a huge improvement over the usual timeframe of fractions of a second.
The objects in question are a pair of vibrating drumheads, made of metallic aluminum on a silicon chip. With a diameter close to the width of a human hair, they're the largest individual objects to have been quantum entangled to date. Other "macroscale" experiments have been performed, but these involved entangling many pairs of electrons and nuclei in an area about the size of a red blood cell.
In the new experiments, the drumheads are cooled to -273° C (-459.4° F), just a hair above absolute zero. Then, they're brought into a quantum entangled state, with the cold helping reduce any outside interference.
"The vibrating bodies are made to interact via a superconducting microwave circuit," says Mika Sillanpää, lead researcher on the study. "The electromagnetic fields in the circuit carry away any thermal disturbances, leaving behind only the quantum mechanical vibrations."
The researchers say that the study paves the way for more precise manipulation of the properties of macroscale objects, which could eventually be put to use to make new kinds of routers and sensors. In future work, the team plans to use quantum teleportation to transmit the vibrations between the two drumheads.
The research was published in the journal Nature.
Source: Aalto University
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