Schrödinger’s Cat, for those unfamiliar, is a famous thought experiment in physics relating to the concept of quantum superposition and the impact of observation on experimentation. The idea is simple: there’s a cat inside of a sealed box, along with a flask of poison, and some sort of radioactive material which will cause the flask to shatter. But one cannot know for certain whether the cat has been killed—not unless one opens the box, acting upon the circumstances as an observer. Until that moment, however, we cannot know for certain whether the cat is dead or alive. In terms of quantum physics, this means that, for a brief time, the cat is simultaneously both dead and alive—until one of us opens the box and collapses both possibilities into a single reality.
This idea has been around for nearly a century now. Even in the best experiments, one can only create a sealed box containing two divergent realities for a very short period of time. After all, there are so many factors threatening to permeate that box and observe the singular reality within it; literally, any attempt to measure or track what’s going on inside of the box would automatically count as an act of observance, thereby collapsing the potential realities.
But now, a group of researchers at the University of Science and Technology of China have used atoms trapped by light to sustain the quantum superposition of a hypothetical cat for a record-breaking twenty-three minutes.
From the paper’s abstract:
Here we demonstrate a long-lived Schrödinger-cat state of optically trapped Yb (I = 5/2) atoms. The cat state, a superposition of two oppositely-directed and furthest-apart spin states, is generated by a non-linear spin rotation. Protected in a decoherence-free subspace against inhomogeneous light shifts of an optical lattice, the cat stateachieves a coherence time of 1.4(1)×10^3s. A magnetic field is measured with Ramsey interferometry, demonstrating a scheme of Heisenberg limited metrology for atomic magnetometry, quantum information processing, and searching for new physics beyond the Standard Model.
What does that all mean? No idea, though they do go into some details regarding the establishment of their hypothetical box—or, rather, the “generation of cat-state,” as they put it.
The folks at NewScientist did a much better job than I could at simplifying the circumstances:
Typically, disturbances from the atoms’ environment would collapse them into a single spin state in a matter of seconds or milliseconds, but the researchers tuned their lasers just right to make the cat states last an unprecedented 1400 seconds – or the length of the average sitcom episode.
[…]
Such a state is very sensitive to everything that happens in its environment, so it could be used to detect and study subtle magnetic forces or to probe new and exotic effects in fundamental physics, he says. “A probe gets jiggled and pushed and nudged and prodded, and then by seeing what happens, you learn about the things that interact with it.”
23 minutes of two divergent realities co-existing together. That’s pretty cool.
Minutes-scale Schrödinger-cat state of spin-5/2 atoms [Y. A. Yang, W.-T. Luo, J.-L. Zhang, S.-Z. Wang, Chang-Ling Zou, T. Xia, Z.-T. Lu / Arxiv]
Quantum ‘Schrödinger’s cat’ survives for a stunning 23 minutes [Karmela Padavic-Callaghan / New Scientist]
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