Natural mode entanglement as a resource for quantum communication

TL;DR

This paper shows that natural mode entanglement in ultra-cold atomic gases can be harnessed for quantum communication protocols like dense coding and teleportation, overcoming superselection rule restrictions.

Contribution

It demonstrates the use of mode entanglement of a single massive particle for quantum communication, providing schemes that reach optimal channel capacities without shared reservoirs.

Findings

Dense coding capacity achieved without shared reservoir

Full quantum channel capacity reached with shared coherent reservoir

Mode entanglement enables quantum communication despite superselection rules

Abstract

Natural particle-number entanglement resides between spatial modes in coherent ultra-cold atomic gases. However, operations on the modes are restricted by a superselection rule that forbids coherent superpositions of different particle numbers. This seemingly prevents mode entanglement being used as a resource for quantum communication. In this paper, we demonstrate that mode entanglement of a single massive particle can be used for dense coding and quantum teleportation despite the superselection rule. In particular, we provide schemes where the dense coding linear photonic channel capacity is reached without a shared reservoir and where the full quantum channel capacity is achieved if both parties share a coherent particle reservoir.