Single-particle Entanglement and Its Application to Quantum Information Processing

Samuel L. Braunstein

Shengwang Du

We investigate the single-particle multi-mode "entanglement" and raise the questions: Is a single particle always entangled? Is entanglement a physical reality which is invariant under an arbitrary unitary transformation or choice of mode basis? We show that, if accepting the single-particle entanglement picture, a single particle can always be entangled by choosing a proper mode basis. This "mode entanglement", expressed as a superposition of single-particle mode basis, may have important applications in quantum information processing as it has some similar mathematical features as the multi-particle entanglement.

Klaus Mølmer, Anders Søndberg Sørensen

Shengwang Du

We investigate the single-particle multi-mode "entanglement" and raise the questions: Is a single particle always entangled? Is entanglement a physical reality which is invariant under an arbitrary unitary transformation or choice of mode basis? We show that, if accepting the single-particle entanglement picture, a single particle can always be entangled by choosing a proper mode basis. This "mode entanglement", expressed as a superposition of single-particle mode basis, may have important applications in quantum information processing as it has some similar mathematical features as the multi-particle entanglement.

Sakar Parajuli

Sougato Bose, Susana F. Huelga, Daniel Jonathan +4 more

Entanglement manipulation, and especially Entanglement Swapping is at the heart of current work on quantum information processing, purification and quantum teleportation. We will discuss how it may be generalized to multiparticle systems and how this enables multi-user quantum cryptographic protocols to be developed. Our scheme allows us to establish multiparticle entanglement between particles which belong to distant users in a communication network through a prior distribution of Bell state singlets followed by local measurements. We compare our method for generating entanglement with existing schemes using simple quantum networks, and highlight the advantages and applications in cryptographic conferencing and in reading messages from more than one source through a single quantum measurement. We also discuss how entanglement leads to the idea of ‘telecloning’, in which a teleportation-like protocol can be found which reproduces the output of an optimal quantum cloning machine. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.