Figure 3: Verification of the photon–phonon entanglement.
From: Quantum teleportation from light beams to vibrational states of a macroscopic diamond
(a) Coincidence counts of Stokes and anti-Stokes photons, as a function of the rotation angle (in degree) of the polarizer (P2 in Fig. 2) for the Stokes photon when the measurement basis of the anti-Stokes photon is fixed at 
. The error bars denote the s.d. (b) Real and imaginary parts of the density matrix elements for the phonon–photon-entangled state reconstructed through the quantum state tomography. The hollow caps correspond to the values of matrix elements for a perfect maximally entangled state. (c) Same as b, but we subtract the background noise due to the accidental coincidences of the photon detectors. The coincidence count rate for Stokes and anti-Stokes photons is 8 per s for measurements in the UU and LL bases.
