Quantum teleportation, evoking as it does images of Star Trek-like transporters, hasn’t quite lived up to its promise. It has never managed to transport more than a few fragile photons over short distances. Now there’s a system that can potentially teleport thousands of substantial particles – without any quantum hang-ups.
Teleportation usually refers to a process that relies on quantum entanglement, where two particles are linked regardless of the distance between them, so that any change to the state of one instantly changes its twin. However, entangled particles are difficult to prepare and delicate to handle, imposing severe limits on quantum teleportation.
Now physicist Ashton Bradley’s team at the Australian Research Council Center of Excellence for Quantum Atom Optics in Brisbane is proposing a technique that avoids quantum entanglement entirely. “We’re talking about a beam of about 5000 particles disappearing from one place and appearing somewhere else,” says Bradley. “We feel that our scheme is closer in spirit to the original fictional concept,” he adds. While the technique can also transmit quantum information in the beam, the technique itself does not rely on the quantum properties of particles, so the team have dubbed the new method “classical teleportation”. (Watch an animation here)
They hit upon the idea by accident. “We were messing around with a way to sensitively measure the quantum properties of an atom beam when we realised we could efficiently use the technique to transport matter,” says Bradley.
In their method, a beam of rubidium atoms is fired into a “sender” device, also made from rubidium atoms (see Diagram). At the same time, a “control” laser pulse is