Welcome to the quantum science podcast. Each episode we bring you stories about developments in science and mathematics. I'm Susan Vallett. While devising a new quantum algorithm, four researchers accidentally established a hard limit on the spooky phenomenon. That's next.

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Quantum Magazine's podcast, The Joy of Why. New episodes drop every other Thursday.

Nearly a century ago, physicist Erwin Schrodinger called attention to a quirk of the quantum world that is fascinated and vexed researchers ever since. When quantum particles such as atoms

interact, they shed their individual identities in favor of a collective state that's greater and weirder than the sum of its parts.

This phenomenon is called entanglement.

Iwin Tang is a researcher at the University of California, Berkeley.

People don't know what entanglement is, right?

That's like one of the central mysteries is quantum information. People don't know what entanglement is, right? Like, that's like

one of the central mysteries of quantum information. People have been trying to understand this thing

for a long time. Researchers have a firm understanding of how entanglement works in idealized systems

containing just a few particles. But the real world is more complicated. In large arrays of atoms, like the ones that make up the stuff we see and touch, the laws of quantum physics compete with the laws of thermodynamics. Things get messy.

At very low temperatures, entanglement can spread over long distances, engulfing many atoms and giving rise to strange phenomena such

as superconductivity. Crank up the heat, though, and atoms jitter about, disrupting the fragile

links that bind entangled particles. Physicists have long struggled to pin down the details

of this process.

Now, a team of four researchers has proven that entanglement doesn't just weaken as temperature increases.

Rather, in mathematical models of quantum systems, such as the arrays of atoms and physical materials,

there's always a specific temperature above

...