Figure 1: Scheme for quantum teleportation with a diamond.

(a) Illustration of the relevant level structure in the diamond. A write beam pumps the diamond in the ground state and generates a Stokes photon in the forward direction and an excitation in the optical phonon mode of the diamond (denoted by the state ). The optical phonon mode corresponds to the relative oscillation of the atoms in each unit cell of the diamond lattice, as illustrated by the figure on the right side. A read beam after a controllable delay converts the phonon excitation to an anti-Stokes photon that can be used for state readout. The corresponding wavelengths and frequencies are shown in the figure. The state denotes the electron conduction band that is far detuned from the optical excitation. (b) A scheme for generation of the entanglement between a phonon in the diamond and a propagating photon. The phonon state is represented by a superposition of different oscillation modes of the diamond, while the photon state is represented by its spatial modes. (c) Readout of the phonon state with the read beams by coherently converting the phonon modes into the corresponding anti-Stoke photon modes. (d) A teleportation scheme using the photon–phonon entanglement. An input state is prepared by the message sender, Alice, on the photon’s polarization degree of freedom. The photon thus carries two qubits, one by its polarization and one by its spatial modes. Alice performs Bell measurements on these two qubits. Conditional on certain measurement outcomes, the phonon state is projected to the same state input on Alice’s side, which is read out and verified by Bob, the message receiver.