A team of physicists from Stanford University have set the quantum record for an object being in two places at once, demonstrating the effect at a distance of over half a meter. The findings were published in the journal Nature.
According to the quantum superposition principal, an object can exist in two quantum states at the same time until it is directly observed, causing its wave function to collapse into one state or the other. Until now, the record for such superposition was under a centimeter distance, for about a quarter of a second. The new results out of Stanford smash this record, and show for the first time that superposition works on macro, human scales.
“Our work really is definitive for large separations. Nobody else has done that,” said team member Mark Kasevich.
Using a new process the team came up with, researchers achieved superposition for about a second, at a remarkable distance of 54 centimeters apart, obliterating the old record.
“They’ve explored the unknown,” said Klaus Hornberger, a physicist at the University of Duisburg-Essen in Germany.
The experiment involved cooling a vacuum sealed chamber to absolute zero and minutely fine tuning it to take into account the Earth’s rotation. The team created what’s called a Bose Einstein condensate (BEC), which is a ball of rubidium atoms all in the same quantum state. Using lasers, they shot this bundle of atoms up the 10 meter high chamber and gradually split the atoms into two separate states.
At the top of the chamber, the BEC’s wave function is split into an even mixture of two states, about 54 centimeters apart. It achieves superposition for about a second then falls back down. As the BEC falls back down, the lasers guide the two states back into one. Observations show that the atoms fall from different heights, confirming that the BEC was in two separate states (superposition) at the top of the chamber.
The results are an important breakthrough in understanding how quantum mechanics (the microscopic universe) transitions to the distances and timescales of everyday life (the macroscopic universe).
“We’re all wondering whether there is some regime where superpositions turn into classical states of matter,” says Kasevich.
The study firmly suggests that quantum phenomena, such as superposition, remain possible in everyday realms. We can only hope that the breakthroughs continue, and by next holiday season we can all be in two places at once (wouldn’t that be helpful).