Quantum teleportation in space and frequency using entangled pairs of photons from a frequency comb

Using entangled pairs of photons from a frequency comb and wide-band frequency-resolved homodyne detection, we propose a sequential quantum teleportation protocol for continuous variables that teleports an unknown state in space and frequency. A subthreshold optical parametric oscillator (OPO) produces a comb of entangled pairs of photons separated by the free spectral range of the OPO cavity. Wide-band frequency-resolved homodyne detection enables direct access to the sum and difference of quadratures between different teeth in the comb. Such measurements are Einstein-Podolsky-Rosen nullifiers, and can be used as the basis for teleportation protocols. Our protocol for space-and-frequency teleportation effectively links arbitrary frequency channels for frequency-division multiplexing, which has applications in universal quantum computation and large-capacity quantum communication.

Figure 1

(a) Schematic diagram of wide-band frequency-resolved homodyne measurement on two teeth in a frequency comb, $A_s$. (b) Equivalent optical mixing and measurements on two spatially separated modes, $A_1$ and $A_2$. LPF: low-pass filter.

Figure 2

(a) Schematic diagram of wide-band frequency-resolved homodyne measurement on four teeth in a frequency comb, $A_s$. By extending the demodulation with signals of different frequencies, we can simultaneously access each tooth in the comb. (b) Equivalent optical mixing and measurements on four spatially separated modes, $A_1,A_2,A_3$, and $A_4$.

Figure 3

Schematic diagram of entanglement swapping.

Figure 4

Schematic diagram of quantum teleportation using a pair of sidebands in a comb of entanglement.

Figure 5

(a) Schematic diagram of sequential teleportation based on a comb of entanglement (b) Conventional sequential teleportation based on spatially separated $2N$ squeezed vacuum states ($A_1$ to $A_{2N}$). X and Z are phase space displacements.