Spooky Action

One of the strangest aspects of quantum physics is entanglement: If you observe a particle in one place, another particle—even one light-years away—will instantly change its properties, as if the two are connected by a mysterious communication channel. Scientists have observed this phenomenon in tiny objects such as atoms and electrons. But in two new studies, researchers report seeing entanglement in devices nearly visible to the naked eye.
“There really is an interesting open question, which is: ‘How far can you go up in scale?’” says Andrew Armour, a physicist at the University of Nottingham in the United Kingdom who wasn’t involved in the work. The advance could also pave the way for ultrasensitive measurements of gravity and a hack-proof quantum internet.
Albert Einstein colorfully dismissed quantum entanglement—the ability of separated objects to share a condition or state—as “spooky action at a distance.” Over the past few decades, however, physicists have demonstrated the reality of spooky action over ever greater distances—even from Earth to a satellite in space. But the entangled particles have typically been tiny, which makes it easier to shield their delicate quantum states from the noisy world.

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