Albert Einstein famously dismissed quantum physics as “spooky action at a distance”, but quantum science may have the last word, with researchers in Brisbane and Tokyo finally providing the missing experimental proof.

Researchers from the Australian Research Council (ARC) Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) have proved this spooky action, by showing that measurements made on a photon’s wavefunction in one lab affected the photon’s quantum state monitored in another lab, metres away.

Einstein had previously dismissed the theory that a quantum particle could appear to be in many different locations at once.

A quantum particle could have a wavefunction spread over a huge distance, indicating its probability of existing in each location, but the particle would never actually exist anywhere until a measurement was made to determine its position. At that point the wavefunction would collapse; the particle would then appear at one location and disappear, instantly, everywhere else.

Einstein’s “spooky action” dismissal has spurred almost nine decades of research.

But the CQC2T researchers cracked the 90- year old challenge by measuring the photon’s wave properties in the first lab, rather than trying to detect its presence or absence.

“If we try to see where it is, we collapse the waveform—it can only be seen in one place at a time. But we sneak up on it by only measuring its wave properties instead,” explains Howard Wiseman, leader of the Griffith University node of the Centre.

By monitoring the photon’s quantum state in the second lab, they proved that the measurement choice in the first lab influenced the quantum state of the photon in the second lab.

For more information: ARC Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Tony Raeside, admin-cqc2t@unsw.edu.au, www.cqc2t.org