Figure 1

Left: Level configuration of an atom in a cavity. Right: Schematic setup to implement a two-atom controlled phase gate by cavity-assisted polarized-photon scattering.Reuse & Permissions

Figure 2

(Color online) Schematic setup for a single-logic-qubit operation $\tilde{H}$ and time control sequence of TR1 and TR2. $\text{D}i$ is a detector, C is a circulator. HWP1 rotates the photon polarization as $|h⟩\leftrightarrow |v⟩$. TR can be controlled exactly as needed to transmit or reflect a photon. The single-photon pulse’s path for $\tilde{H}$ is port $i$–TR1-C-PBS-cavity-PBS-C-TR2-HWP1-M-TR1-C-PBS- cavity-PBS-C-TR2-${\text{P}}_{45}\text{-D}i$. The states of TR1 and TR2 can be controlled accurately by computer. $T_0$ is the time for the single-photon pulse process TR1-C-PBS-cavity-PBS-C-TR2, while $T_1$ is the time for TR2-HWP1-M-TR1.Reuse & Permissions

Figure 3

(Color online) Schematic setup for two-logic-qubit conditional phase gate ${\tilde{U}}_{\text{CZ}}^{i,j}$ $\left({\tilde{U}}_{\text{CZ}}^{j,i}\right)$ which uses the additional channel shown by dashed gray lines. HWP2 performs a Hadamard gate on the photon polarization states. The single-photon pulse’s path for ${\tilde{U}}_{\text{CZ}}^{i,j}$ $\left({\tilde{U}}_{\text{CZ}}^{j,i}\right)$ is port $i$–TR1-$\text{TR}{1}^{*}$-C-PBS–cavity $i$–PBS-C-TR2-HWP1-M-TR1-HWP2-$\text{TR}{3}^{*}$-TR3-C-PBS–cavity $j$–PBS-C-TR4-${\text{P}}_{45}\text{-D}j$ (port $j$–$\text{TR}{3}^{*}$-TR3-C-PBS–cavity $j$–PBS-C-TR4-HWP1-M-TR3-HWP2-$\text{TR}{1}^{*}$-C-PBS–cavity $i$–PBS-C-TR2-${\text{P}}_{45}\text{-D}i$). Unlike $\tilde{H}$, the TRs remain unchanged during the conditional phase gating.Reuse & Permissions