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The resonance energy transfer and entanglement between two-level quantum emitters are typically limited to sub-wavelength distances due to the inherently short-range nature of the dipole–dipole interactions. Moreover, the entanglement of quantum systems is hard to preserve for a long time period due to decoherence and dephasing mainly caused by radiative and nonradiative losses. In this work, we outperform the aforementioned limitations by presenting efficient long-range inter-emitter entanglement and large enhancement of resonance energy transfer between two optical qubits mediated by epsilon-near-zero (ENZ) and other plasmonic waveguide types, such as V-shaped grooves and cylindrical nanorods. More importantly, we explicitly demonstrate that the ENZ waveguide resonant energy transfer and entanglement performance drastically outperforms the other waveguide systems. Only the excited ENZ mode has an infinite phase velocity combined with a strong and homogeneous electric field distribution, which leads to a giant energy transfer and efficient entanglement independent of the emitters’ separation distances and nanoscale positions in the ENZ nanowaveguide, an advantageous feature that can potentially accommodate multi-qubit entanglement. Moreover, the transient entanglement can be further improved and become almost independent of the detrimental decoherence effect when an optically active (gain) medium is embedded inside the ENZ waveguide. We also present that efficient steady-state entanglement can be achieved by using a coherent external pumping scheme. Finally, we report a practical way to detect the steady-state entanglement by computing the second-order correlation function. The presented findings stress the importance of plasmonic ENZ waveguides in the design of the envisioned on-chip quantum communication and information processing plasmonic nanodevices. 

Current graphene‐based plasmonic devices are restricted to 2D patterns defined on planar substrates; thus, they suffer from spatially limited 2D plasmon fields. Here, 3D graphene forming freestanding nanocylinders realized by a plasma‐triggered self‐assembly process are introduced. The graphene‐based nanocylinders induce hybridized edge (in‐plane) and radial (out‐of‐plane) coupled 3D plasmon modes stemming from their curvature, resulting in a four orders of magnitude stronger field at the openings of the cylinders than in rectangular 2D graphene ribbons. For the characterization of the 3D plasmon modes, synchrotron nanospectroscopy measurements are performed, which provides the evidence of preservation of the hybridized 3D graphene plasmons in the high precision curved nanocylinders. The distinct 3D modes introduced in this paper, provide an insight into geometry‐dependent 3D coupled plasmon modes and their ability to achieve non‐surface‐limited (volumetric) field enhancements.