Nanoplasmonic Lattices for Ultracold Atoms

We propose to use subwavelength confinement of light associated with the near field of plasmonic systems to create nanoscale optical lattices for ultracold atoms. Our approach combines the unique coherence properties of isolated atoms with the subwavelength manipulation and strong light-matter interaction associated with nanoplasmonic systems. It allows one to considerably increase the energy scales in the realization of Hubbard models and to engineer effective long-range interactions in coherent and dissipative many-body dynamics. Realistic imperfections and potential applications are discussed.

Figure 1

(a) Illustration of the relevant physics in the plasmonic lattice. (b) Illustration of how to engineer a blue-detuned optical dipole trap by driving on the blue side of the plasmon resonance. (c) Atomic potential for Rb including vdw for trapping above a single silver nanoshell. The dotted line shows how to weaken the trap by applying circularly polarized light perpendicular to the trapping light. (Inset) Real (dashed line) and imaginary (solid line) part of the dipole polarizability for a sphere and the nanoshell with a 15 nm radius and 13.85 nm ${\mathrm{SiO}}_2$ core. (d) $y\mathrm{\text{−}}z$ contours of atomic potential in megahertz for a line of nine spheres in the center of a $45\times 45$ square lattice with a 60 nm lattice spacing; black regions are where the potential is negative due to vdw, and spheres are shown in white. The nanoshells are silver with a 15 nm radius and 13.65 nm ${\mathrm{SiO}}_2$ core; the trapping light is red-detuned (704 nm) with respect to the plasmon resonance (682 nm) and applied from above with rotating $x\mathrm{\text{−}}y$ polarized light.

Figure 2

The scaling of the maximum tunneling in the lowest band and the corresponding on-site interaction. Calculated by using the Wannier functions for a sinusoidal potential. (Inset) Energy-dependent scattering length for two ${}^{87}\mathrm{Rb}$ atoms on a single site as a function of the trap frequency.

Figure 3

(a) The cavity QED figure of merit $g^2/\kappa \gamma$ with changing system size assuming the atom is trapped at a distance of twice the sphere radius. We show the scaling for both silver and gold nanoshells with a $Q$ of 80 and 20, respectively. (Inset) Single atom trapped above a nanosphere acts as a cavity QED system with atomic and cavity losses $\gamma$ and $\kappa$, respectively, and a coherent coupling $g$. (b) Fidelity for generating a ground state singlet state between two atoms on the lattice with their separation after optimization. The entanglement is generated through interaction with the collective plasmon modes, where we took the metal losses of bulk silver. (Inset) Scalable cavity QED array of atoms and plasmons.