  Nondegenerate four-wave mixing (FWM) process based on a double-$\Lambda$
scheme in hot alkali metal vapor is a versatile tool in quantum state
engineering, quantum imaging, and quantum precision measurements. In this
Letter, we investigate the generation of quantum correlated twin beams which
carry nonzero orbital angular momentums (OAMs) based on the FWM process in hot
cesium vapor. The amplified probe beam and the newly generated conjugate beam
in the FWM process have the same and opposite topological charge as the seed
beam, respectively. We also explore the FWM process operated in a nonamplifying
regime where quantum correlated twin beams carrying OAMs can still be
generated. In this regime, the FWM process plays the role of quantum beam
splitter for the OAM of light, that is, a device that can split a coherent
light beam carrying OAM into quantum-correlated twin beams carrying OAMs. More
generally, our setup can be used as a quantum beam splitter of images.

Quantum Physics