In a breakthrough for quantum physics and hypothetical felines – scientists have managed to create a ‘Schrödinger’s cat’ state at unusually warm temperatures.
It’s a state that taps into one of the strangest principles in quantum mechanics: the idea that particles can exist in two different states at once, a concept known as superposition.
To illustrate just how bizarre this idea is, Austrian-born 20th century physicist Erwin Schrödinger devised his now-famous thought experiment, known as Schrödinger’s cat.
In the analogy, a cat placed in a box with poison gas, which would be released upon the radioactive decay of an atom, would be, to all intents and purposes, both simultaneously alive and dead.
Physicists have for some time been able to create real-life Schrödinger cat particles – where either the position of atoms or the oscillations of electromagnetic resonators exist in two states at once.
However, to produce these states quantum objects had to be cooled to their ground states – the lowest possible energies found at temperatures close to absolute zero (–273°C).
Now, for the first time, a new study published in the journal Science Advances has unveiled the creation of quantum superpositions at temperatures above the ground state.
“Schrödinger also assumed a living – i.e., ‘hot’ – cat in his thought experiment,” said Prof Gerhard Kirchmair, a physicist at the University of Innsbruck, Austria, and co-author of the new study. “We wanted to know whether these quantum effects can also be generated if we don't start from the ‘cold’ ground state.”
Kirchmair and his colleagues succeeded, generating Schrödinger cat states at temperatures of 1.8 Kelvin. This is still very cold by everyday standards – a chilly –271°C – but significantly warmer than what's typically required in quantum experiments.
“Many of our colleagues were surprised when we first told them about our results, because we usually think of temperature as something that destroys quantum effects,” said Thomas Agrenius, another scientist involved in the study.
“Our measurements confirm that quantum interference can persist even at high temperatures.”
The findings have significant implications. Quantum computers promise to revolutionise technology because they can operate in multiple states rather than binary ones and zeros. But they currently rely on expensive cooling experiments to achieve the desired quantum effects. This finding could change all that.
“Our work reveals that it is possible to observe and use quantum phenomena even in less ideal, warmer environments,” Kirchmair said. “If we can create the necessary interactions in a system, the temperature ultimately doesn't matter.”
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