Remote State Preparation: Arbitrary Remote Control of Photon Polarization

We experimentally demonstrate the first remote state preparation of arbitrary single-qubit states, encoded in the polarization of photons generated by spontaneous parametric down-conversion. Utilizing degenerate and nondegenerate wavelength entangled sources, we remotely prepare arbitrary states at two wavelengths. Further, we derive theoretical bounds on the states that may be remotely prepared for given two-qubit resources.

Figure 1

Experimental arrangement for remote state preparation. The entangled state $(|DD⟩+|AA⟩)/\sqrt{2}$ is generated by equally pumping two BBO crystals whose optic axes are in perpendicular planes [the relative phase is adjusted by tipping a HWP ($\varphi$-plate) about its vertical optic axis]. The trigger photon is then partially projected into an arbitrary polarization state with a QWP and a HWP located before a partial polarizer [12] shown in the dashed box. Conditional on detection of this photon, the sister photon is prepared into the desired state.

Figure 2

Remotely prepared states shown in the Poincaré sphere. (a) States remotely prepared at 702 nm using frequency degenerate entanglement. (b) States remotely prepared at 670 nm (using a 737 nm trigger). In either case, the distance of the remotely prepared state from the origin is indicated by its color: $\mathrm{\text{red}}\to \mathrm{\text{mixed}}$, $\mathrm{\text{blue}}\to \mathrm{\text{pure}}$. Lines are drawn along the data to guide the eye.