Evanescent-field-modulated two-qubit entanglement in an emitters-plasmon coupled system

Abstract

Scalable integrated quantum information network calls for controllable entanglement modulation at subwavelength scale. To reduce laser disturbance among adjacent nanostructures, here we theoretically demonstrate two-qubit entanglement modulated by an evanescent field of a dielectric nanowire in an emitter-AgNP coupled system. This coupled system is considered as a nano-cavity system embedded in an evanescent vacuum. Through varying the amplitude of evanescent field, the concurrence of steady-state entanglement can be modified from 0 to 0.75. Because the interaction between emitters and the nanowire is much weaker than that inside the coupled system, the range of modulation for two-qubit entanglement is insensitive to their distance. The evanescent field controlled entangled state engineering provides the possibility to avoid optical crosstalk for on-chip steady-state entanglement.

Entangled dark state mediated by a dielectric cavity within epsilon-near-zero materials

“…where ρ is the density matrix of the system, κ i is the cavity loss of the i-th mode, with i = 1 corresponding to the 2-TM mode and i = 2 corresponding to the 4-TE mode. Cavity losses mainly come from the absorption of ENZ materials, unlike plasmonic cavity structures, where the cavity loss mainly originates from the radiation and Ohmic losses [19,35]. In our system, κ i corresponds to the half-height width of the cavity mode radiation power spectra.…”

“…structures, such as metal nanoparticles [10][11][12], nanoantennas [13,14], and plasmonic waveguides [15][16][17][18], can enhance the entanglement between two emitters through near-field effects or the high local density of states. The combination of metal spheres and nanowires also provides a means to control entanglement [19]. Utilizing metasurfaces to manipulate scattering fields enables the entanglement between qubits separated by a macroscopic distance [20].…”