Quantum physicists just supersized Schrodinger's cat. What happens next could be revolutionary

"A team based at the University of Vienna put individual clusters of around 7,000 atoms of sodium metal some 8 nanometres wide into a superposition of different locations, each spaced 133 nanometres apart. Rather than shoot through the experimental set up like a billiard ball, each chunky cluster behaved like a wave, spreading out into a superposition of spatially distinct paths and then interfering to form a pattern researchers could detect."

"Quantum theory doesn't put a limit on how big a superposition can be, but everyday objects clearly do not behave in a quantum way, she explains. This experiment which puts an object as massive as a protein or small virus particle into a superposition is helping to answer the big, almost philosophical question of is there a transition between the quantum and classical?', she says. The authors show that, at least for clusters of this size, quantum mechanics is still valid."

"The experiment, described in Nature on 21 January, is of practical importance, too, says Giulia Rubino, a quantum physicist at the University of Bristol, UK. Quantum computers will ultimately need to maintain perhaps millions of objects in a large quantum state to perform useful calculations. If nature were to make systems collapse past a certain point, and that scale was smaller than what is needed to make a quantum computer, then that's problematic, she says."

Researchers created spatial superpositions of sodium metal clusters containing about 7,000 atoms, roughly 8 nanometres wide, with path separations of 133 nanometres. The clusters propagated as waves rather than classical particles and produced detectable interference patterns. The result demonstrates that quantum mechanics remains valid at masses comparable to proteins or small viruses. The work probes whether a transition exists between quantum and classical behavior and constrains hypothetical collapse mechanisms. The finding also has practical implications for quantum computing, since maintaining large coherent states across many objects is required for useful quantum processors.

Read at www.nature.com