8 months ago
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Nothing makes a mess of quantum physics quite like those space-warping, matter-gulping abominations known as black holes. If you want to turn Schrodinger's eggs into an information omelet, just find an event horizon and let 'em drop.
According to theoretical physicists and chemists from Rice University and the University of Illinois Urbana-Champaign in the US, basic chemistry is capable of scrambling quantum information almost as effectively.
The team used a mathematical tool developed more than half a century ago to bridge a gap between known semiclassical physics and quantum effects in superconductivity. They found the delicate quantum states of reacting particles become scrambled with surprising speed and efficiency that comes close to matching the might of a black hole.
"This study addresses a long-standing problem in chemical physics, which has to do with the question of how fast quantum information gets scrambled in molecules," says Rice University physics theorist Peter Wolynes.
"When people think about a reaction where two molecules come together, they think the atoms only perform a single motion where a bond is made or a bond is broken."
Behind the classical 'ball and stick' models of atoms sticking together into molecules is a far more complex universe that has more in common with the mathematics of gambling than engineering.
In a quantum landscape, states of possibility can rise and fall like odds in a poker game as the fates of particles intertwine. Every twist and turn in the reaction – every new electron, every added proton – flips a new card that changes the stakes in subtle but critical ways.
Unlike the all-or-nothing events in classical physics where particles bond or bounce based on sufficient measures of energy, quantum states involve elements of chance that can see barriers being breached without tolls being paid.
Known as tunneling, these quantum breachers can make mapping the evolution of quantum states all that harder. What starts as a neat bet quickly becomes a chaotic mess that depends on countless factors to make sense of.
One method of breaking up the tiny changes that define quantum chaos employs something called out-of-time-order correlators, or OTOCs. Initially developed to model superconductivity in the 1960s, they made a comeback decades later to make sense of the way information spreads in black holes.
"How quickly an OTOC increases with time tells you how quickly information is being scrambled in the quantum system, meaning how many more random looking states are getting accessed," says Illinois Urbana-Champaign chemist Martin Gruebele.
The team's calculations demonstrated tunneling is most likely to occur among confined groups of particles that require little energy to react, especially when they are kept at a sufficiently low temperature.
In fact, this tendency for tunneling to emerge in such twitchy reactions can scramble quantum information on a subpicosecond time scale. That's in the ballpark of black holes, which are the true masters at taking quantum states and mashing them all together into a bland pulp.
Curiously, when those same reactions take place in a more real-world environment – such as a bulky solution or a biological soup of materials – the same scrambling behavior is "quenched".
It's hoped that by finding the right tools for mapping quantum chaos on a chemistry level engineers might be able to fine-tune materials to minimize tunneling where it isn't wanted, or control it for innovative applications.
"There's potential for extending these ideas to processes where you wouldn't just be tunneling in one particular reaction, but where you'd have multiple tunneling steps," Gruebele says, "because that's what's involved in, for example, electron conduction in a lot of the new soft quantum materials like perovskites that are being used to make solar cells and things like that."
This researched was published in PNAS.
