Figure 1

(Color online) (a) Energy levels of ${}^{87}\mathrm{Rb}$, and the frequency arrangement of the lasers used in this experiment, where $\mid a⟩$ and $\mid b⟩$ are the hyperfine sublevels of the ground state, and $\mid c⟩$ and $\mid d⟩$ are excited states. (b) Schematic setup of our experiment. A strong coupling laser and a weak pump laser with orthogonal linear polarization counterpropagate through the rubidium cell. Paired Stokes photons and anti-Stokes photons are generated in phase-matched directions. H1 and H2 are computer-generated holograms; SMF1 and SMF2 are single-mode fibers, which collect the $\mp 1$ diffraction of H1 and H2, and connect to single photon-counting modules (SPCM); F1 and F2 are filters, each of which is combined with an optical pumped rubidium cell and a ruled diffraction grating.Reuse & Permissions

Figure 2

(Color online) Time-resolved coincidence counts between the Stokes photons and the anti-Stokes photons. The data is accumulated for about $1000\text{seconds}$ and then normalized in time. $\tau$ is the relative delay between the Stokes photons and the anti-Stokes photons.Reuse & Permissions

Figure 3

(Color online) Coincident counts versus the displacements of H2 with different displacement of H1. (a) shows the results that the Stokes photons are in stationary states ∣0⟩ (red squares) and ∣1⟩ (green dots); (b) shows the results that the Stokes photons are in the superposition states $(\mid 0⟩\pm \mid 1⟩)∕\sqrt{2}$. The data are fitted by using the square of Eq. (5) with $w=0.8\mathrm{mm}$.Reuse & Permissions

Figure 4

(Color online) Graphical representation of the reconstructed density matrix. (a) is the real part and (b) is the imaginary part.Reuse & Permissions