Finger M A, Iskhakov T Sh, Joly N Y, Chekhova M V and Russell P St J 2015 Raman-free, noble-gas-filled PCF source for ultrafast, very bright twin-beam squeezed vacuum Phys. Rev. Lett. 115 143602Finger M A, Iskhakov T S, Joly N Y, et al. Raman-free, noble-gas-filled photonic...