Atom-Light Interactions in Photonic Crystals

Abstract

The integration of nanophotonics and atomic physics has been a long-sought goal that would open new frontiers for optical physics. Here, we report the development of the first integrated optical circuit with a photonic crystal capable of both localizing and interfacing atoms with guided photons in the device. By aligning the optical bands of a photonic crystal waveguide (PCW) with selected atomic transitions, our platform provides new opportunities for novel quantum transport and many-body phenomena by way of photon-mediated atomic interactions along the PCW. From reflection spectra measured with average atom numberN = 1.1 ± 0.4, we infer that atoms are localized within the PCW by Casimir-Polder and optical dipole forces. The fraction of single-atom radiative decay into the PCW is Γ1D/Γ (0.32 ± 0.08), where Γ1D is the rate of emission into the guided mode and Γ is the decay rate into all other channels. Γ1D/Γ is quoted without enhancement due to an external cavity and is unprecedented in all current atom-photon interfaces.Localizing arrays of atoms in photonic crystal waveguides with strong atom-photon interactions could provide new tools for quantum networks [1][2][3] and enable explorations of quantum many-body physics with engineered atom-photon interactions [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Bringing these scientific possibilities to fruition requires creation of an interdisciplinary 'toolkit' from atomic physics, quantum optics, and nanophotonics for the control, manipulation, and interaction of atoms and photons with a complexity and scalability not currently possible. Here, we report advances that provide rudimentary capabilities for such a 'toolkit' with atoms coupled to a photonic crystal waveguide (PCW). As illustrated in Fig. 1, we have fabricated the first integrated optical circuit with a photonic crystal whose optical bands are aligned with atomic transitions for both trapping and interfacing atoms with guided photons [20,21]. The quasi-1D PCW incorporates a novel design that has been fabricated in silicon nitride (SiN) [21,22] and integrated into an apparatus for delivering cold cesium atoms into the near field of the SiN structure. From a series of measurements of reflection spectra withN = 1.1 ± 0.4 atoms coupling to the PCW, we infer that the rate of single-atom radiative decay into the waveguide mode is Γ 1D (0.32±0.08)Γ , where Γ is the radiative decay rate into all other channels. The corresponding single-atom reflectivity is |r 1 | 0.24, representing an optical attenuation for one atom greater than 40% [12,20]. For comparison, atoms trapped near the surface of a fused silica nanofiber exhibit Γ 1D (0.04 ± 0.01)Γ [23-25], comparable to observations with atoms and molecules with strongly focused light [26,27]. Here, Γ 1D refers to the emission rate without enhancement or inhibition due to an external cavity. By comparing with numerical simulations, our measurements suggest that atoms are guided to unit cells of the PCW by the combination of Casimir-Polder and optical ...

Diagrammatic Approach to Scattering of Multi-Photon States in Waveguide QED

“…Although photons are the excellent carriers of quantum information, capable of high fidelity entanglement and information transfer [10][11][12], recent advancement in quantum electronics offers a large variety of alternatives. Most commonly, nowadays, waveguide QED setups are realized in the experiments with superconducting quantum circuits, where superconducting transmission lines act as quantum radiation channels, whereas the Josephsonjunction-based superconducting quantum bits play the role of quantum emitters [13][14][15].…”

“…10,10,10 (0) + T (3,C)µ 1 k 1 ,µ 3 k 3 ,µ 2 k 2 ,10,10,10 (0) + T k 3 ,µ 1 k 1 ,µ 2 k 2 ,10,10,10 (0) + T (3,C) µ 2 k 2 ,µ 1 k 1 ,µ 3 k 3 ,10,10,10 (0) + T (3,C) µ 2 k 2 ,µ 3 k 3 ,µ 1 k 1 ,10,10,10 (0) . (B2)…”