Beam me up: Each of the two cylindrical chambers (left and right) holds a single atom. The black tubes in the foreground are used to image each atom. Optical fibers that channel single photons from each atom are opposite the tubes, on the left side of the picture, covered in black paper. The photons interfere inside the big black rectangular box at the left.
To perform teleportation, the researchers prepared the left-hand ion in an arbitrary quantum state, and then repeatedly zapped the ions with laser pulses until they saw the pairs of opposite-color photons that heralded the entangled state. They quickly measured which nuclear state the left-hand ion was in, in the process destroying its quantum mixture. But the entanglement causes a closely related mixture to appear in the right-hand ion. The researchers turned this back into a teleported version of the original state by manipulating it in one of two ways, depending on which state they measured for the left-hand ion.
“This is the first realization of quantum teleportation between two remote atoms,” observes Myungshik Kim of Queen’s University Belfast, in Northern Ireland, who was not involved in the work. “It’s a quite clever technique.”
One problem is that it takes almost 100 million laser pulses–about 10 minutes–to get a single entangled pair. To be useful for further experiments, this number needs to be improved about 1,000-fold, mainly by collecting more of the emitted photons. The scheme for teleporting between distant ions could enable quantum repeaters that allow long-distance transmission of quantum information, Monroe notes. In addition, he says that it is well suited for an increasingly studied approach to quantum computation that starts with a large number of entangled qubits.