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.
Highlights
The processing of quantum information carried by photons has reached such a level of maturity that photonic quantum computers are becoming competitive in this technological field [1, 2]
We show that symmetry-protected states are not limited to one- or two-photon states, on the contrary, it can be formally extended to the multiphoton case
We show that states that are protected in postselected scattering at cylindrically symmetric structures (Fig. 1a) can only be constructed in the subspace of input states with total angular momentum equal to zero, agreeing with previous results shown in Ref. [27]
Summary
The processing of quantum information carried by photons has reached such a level of maturity that photonic quantum computers are becoming competitive in this technological field [1, 2]. The interaction of light with these structures can be described from the scattering of the electromagnetic modes, at least in the linear regime, the scattering properties of multiphoton states can be rather complex This is due to quantum interference effects and the fact that one can describe multiphoton states with different sets of orthogonal modes [26]. We consider initial states of a known number of photons in a given set of angular momentum light modes and investigate their scattering on cylindrically symmetric structures. We show that states that are protected in postselected scattering at cylindrically symmetric structures (Fig. 1a) can only be constructed in the subspace of input states with total angular momentum equal to zero, agreeing with previous results shown in Ref.
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