• openAccess   No-go theorems for photon state transformations in quantum linear optics 

      V. Parellada, Pablo; Gimeno i Garcia, Vicent; Moyano-Fernández, Julio José; Garcia-Escartin, Juan Carlos Elsevier (2023)
      We give a necessary condition for photon state transformations in linear optical setups preserving the total number of photons. From an analysis of the algebra describing the quantum evolution, we find a conserved quantity ...