Swapping intraphoton entanglement to interphoton entanglement using linear optical devices

We propose a curious protocol for swapping the intraphoton entanglement between path and polarization degrees of freedom of a single photon to interphoton entanglement between two distance photons that have never interacted. This is accomplished by using an experimental setup consisting of three suitable Mach-Zehnder interferometers along with number of beam splitters, polarization rotators, and detectors. Using the same setup, we have also demonstrated an interesting quantum state transfer protocol, symmetric between Alice and Bob. Importantly, the Bell-basis discrimination is not required in both the swapping and state transfer protocols. Our proposal can be implemented using linear optical devices.

Figure 1

The setup for implementing the swapping of intraphoton path-polarization entanglement of each of the photons in ${\text{MZ}}_1$ and ${\text{MZ}}_3$ to interphoton polarization—polarization entanglement between the photons in ${\text{MZ}}_1$ and ${\text{MZ}}_3$ and for transferring the polarization state of the photon in ${\text{MZ}}_1$ to the photon in ${\text{MZ}}_3$ (details are given in the text).