arXiv:0901.4740 · Physical Review A
Quantum multiplexing with the orbital angular momentum of light
Juan Carlos García-Escartín, Pedro Chamorro‐Posada
Abstract
The orbital angular momentum (OAM) of photons offers a suitable support to carry the quantum data of multiple users. We present two optical setups that send the information of $n$ quantum communication parties through the same free-space optical link. Those qubits can be sent simultaneously and share path, wavelength, and polarization without interference, increasing the communication capacity of the system. The first solution, a qubit combiner, merges $n$ channels into the same link, which transmits $n$ independent photons. The second solution, the OAM multiplexer, uses controlled-not ($\mathrm{CNOT}$) gates to transfer the information of $n$ optical channels to a single photon. Additional applications of the multiplexer circuits, such as quantum arithmetic, as well as connections to OAM sorting are discussed.