Entangled States in Quantum Key Distribution
Gregg S. Jaeger · AIP conference proceedings · 2006
The development of practical optical technology has been essential to empirical explorations of foundational questions in quantum theory, such as tests of Bell inequalities. Here, some current and potential uses of entangled multi‐photon states, which have long lain at the heart of foundational considerations in quantum theory, are explored. The use of quantum decoherence mitigation techniques such as decoherence‐free subspaces (DFSs) which involve such entangled quantum states in non‐trivial Hilbert spaces and which were until recently merely theoretical constructs, are shown capable of playing a role in furthering practical optical QKD and other communication tasks using quantum information resources. Elements of a recently introduced basis of four‐photon entangled states are shown to lie in a decoherence‐free subspace and to result from the concatenation of quantum codes, as examples.