Limitations of practical multiphoton decoherence-free states (4 pages)

Gabriel A. Durkin

Che Sun, Sixia Yu, Fei Xue

Martı́n E. Garcia, Ilya Grigorenko

Yong-Sheng Zhang, Chuan‐Feng Li, Yun‐Feng Huang +1 more

It is shown that the decoherence-free subspace (DFS) of practical multiphoton polarization cannot avoid exponential decoherence even in the same extra environment if the photons are frequency anticorrelated. The reason lies in the fact that the condition of collective decoherence is not satisfied in this case. As an example, the evolution of a biphoton decoherence-free state is given. A possible solution for a feasible multiphoton DFS state is also given.

Erik Díaz-Bautista, David J. Fernández C.

Jon Lasa‐Alonso, Martín Molezuelas‐Ferreras, J J Miguel Varga +3 more

Abstract In this manuscript we analyze the emergence of protected multiphoton states in scattering problems with cylindrical symmetry. In order to do that, we first provide a formal definition of the concept of postselected symmetry-protection. We show that the notion of symmetry-protection is not limited to one- or two-photon states, on the contrary, it can be formally extended to the multiphoton case. In addition, we prove for the case of cylindrical symmetry that all possible multiphoton protected states are constructed from a small set of one- and two-photon states. Finally, we point out possible applications that symmetry-protected states may have in quantum communications, concretely, in the construction of decoherence-free subspaces.