Atoms tend to stay put, but light is always on the move. Physicists would like to exploit those qualities to make information-processing devices in which atoms store information and light shuttles it around (SN: 4/3/99, p. 220). In a step toward that goal, researchers have transmitted quantum states between atoms and light.
Such a transfer of properties is called teleportation. “This is the first case of successful teleportation between objects of a different nature”—namely, photons of energy and atoms of matter, says study coauthor Ignacio Cirac of the Max Planck Institute for Quantum Optics in Garching, Germany.
In experiments since 1998, numerous teams of physicists have demonstrated teleportation of quantum states between objects of the same kind (SN: 6/19/04, p. 387: Teleporting Matter’s Traits: Beaming information quantum-style). For instance, researchers have transferred the orientation of one photon’s electromagnetic field—the light particle’s polarization—to another photon.
In the new experiment, Cirac, Eugene S. Polzik of the Niels Bohr Institute in Copenhagen, and their colleagues teleported traits of a dim laser pulse, including the strength of its electromagnetic field, onto a cloud of 1 trillion cesium atoms.
To do so, the researchers first created a quantum-information bridge between a different, brilliant laser pulse and the atom cloud. That connection formed when the scientists fired the bright pulse through the cloud, causing the photons’ polarizations to become correlated with the cloud’s spin, another quantum trait.
In the language of quantum physics, the brilliant pulse and the atom cloud became “entangled.” When objects are entangled, changes to the quantum state of one immediately affect the other, no matter how distant it is.
Once the researchers had achieved entanglement of the photons and atoms, they mixed the bright and dim pulses. A few further manipulations triggered the desired light-to-matter transfer of the quantum states, the scientists report in the Oct. 5 Nature.