Teleportation for two

Abstract

Non-destructive photon-number measurement Joint measurements C Figure 1 | Teleportation of photon polarization and orbital angular momentum. Photon A, whose polarization and orbital angular momentum are shown with a small arrow and an ellipse, respectively, is measured jointly with photon B, which is quantum-mechanically entangled with photon C. This act consists of: a comparative measurement of the polarizations of photons A and B (CM-P); a non-destructive verification that exactly one photon exits this measurement in path 1, and hence exactly one photon exits in path 2, given that two photons entered CM-P; and a comparative measurement of the orbital angular momenta of photons A and B (CM-OAM). The measurements result in the teleportation (that is, the transfer) of photon A's properties onto photon C. The transfer may require rotations of photon C's (unknown) polarization and orbital angular momentum, as determined by the outcomes of the comparative measurements. Wang et al. 2 have implemented all but the rotation steps in this transfer scheme. Teleporting the polarization alone does not require the non-destructive measurement, the CM-OAM, nor the rotation of photon C's orbital angular momentum. The 'no-cloning' theorem of quantum mechanics forbids the perfect copying of properties of photons or electrons. But quantum teleportation allows their flawless transfer — now even for two properties simultaneously.