  Quantum entanglement is at the heart of quantum information sciences and
quantum technologies. In the optical domain, the most common type of quantum
entanglement is polarization entanglement, which is usually created in a
postselection manner involving destructive photon detection and thus hindering
further applications which require readily available entanglement resources. In
this work, we propose a scheme to prepare multipartite entangled states of
polarized photons in a heralded manner, i.e., without postselection. We exploit
the quantum scissors technique to truncate a given continuous-variable
entanglement into the target entangled states which are of hybrid
discrete-continuous or solely discrete types. We consider two implementations
of the quantum scissors: one modified from the original quantum scissors [Pegg
et al., Phys. Rev. Lett. 81, 1604 (1998)] using single photons and linear
optics and the other designed here using a type-II two-mode squeezer. We
clarify the pros and cons of these two implementations as well as discussing
practical aspects of the entanglement preparation. Our work illustrates an
interface between various types of optical entanglement and the proposed
quantum scissors techniques could serve as alternative methods for heralded
generation of polarization entanglement.
