Immunity of information encoded in decoherence-free subspaces to particle loss
Piotr Migdał, Konrad Banaszek · Physical Review A · 2011
We demonstrate that for an ensemble of qudits, subjected to collective decoherence in the form of perfectly correlated random SU($d$) unitaries, quantum superpositions stored in the decoherence-free subspace are fully immune against the removal of one particle. This provides a feasible scheme to protect quantum information encoded in the polarization state of a sequence of photons against both collective depolarization and one-photon loss and can be demonstrated with photon quadruplets using currently available technology.