Hybrid entanglement carrying orbital angular momentum

Hybrid continuous-variable (CV) and discrete-variable (DV) entanglement is an essential quantum resource of hybrid quantum information processing, which enables one to overcome the intrinsic limitations of CV and DV quantum protocols. Besides CV and DV quantum variables, introducing more degrees of freedom provides a feasible approach to increase the information carried by the entangled state. Among all the degrees of freedom of photons, orbital angular momentum (OAM) has potential applications in enhancing the communication capacity of quantum communication and precision of quantum measurement. Here, we present the experimental preparation of hybrid entanglement carrying OAM, which involves three degrees of freedom including polarization, cat states, and OAM. By converting the wavefront of optical cat states with a q-plate, the OAM degree of freedom is introduced into the prepared hybrid entanglement between a polarization-encoded DV qubit and a cat-encoded CV qubit. Based on the measured topological charges l = 0, +1, +2 and reconstructed Wigner functions of the output states, the hybrid entangled states carrying OAM with l = 0, +1, +2 are confirmed with non-zero logarithmic negativities, respectively. Our work takes a crucial step towards extending the degree of freedom for hybrid entanglement, which provides a new quantum resource for hybrid quantum information processing.