Enhancing Light-Atom Interactions via Atomic Bunching

Abstract

There is a broad interest in enhancing the strength of light-atom interactions to the point where injecting a single photon induces a nonlinear material response. Here, we show theoretically that sub-Doppler-cooled, two-level atoms that are spatially organized by weak optical fields give rise to a nonlinear material response that is greatly enhanced beyond that attainable in a homogeneous gas. Specifically, in the regime where the intensity of the applied optical fields is much less than the off-resonant saturation intensity, we show that the third-order nonlinear susceptibility scales inversely with atomic temperature and, due to this scaling, can be two orders of magnitude larger than that of a homogeneous gas for typical experimental parameters. As a result, we predict that spatially bunched two-level atoms can exhibit single-photon nonlinearities. Our model is valid for all atomic temperature regimes and simultaneously accounts for the back-action of the atoms on the optical fields. Our results agree with previous theoretical and experimental results for light-atom interactions that have considered only a limited range of temperatures. For lattice beams tuned to the low-frequency side of the atomic transition, we find that the nonlinearity transitions from a self-focusing type to a self-defocusing type at a critical intensity. We also show that higher than third-order nonlinear optical susceptibilities are significant in the regime where the dipole potential energy is on the order of the atomic thermal energy. We therefore find that it is crucial to retain high-order nonlinearities to accurately predict interactions of laser fields with spatially organized ultracold atoms. The model presented here is a foundation for modeling low-light-level nonlinear optical processes for ultracold atoms in optical lattices.

References in corpus (18)

• Theory of Photon Blockade by an Optical Cavity with One Trapped Atom
• Cold atoms in cavity-generated dynamical optical potentials
• Efficient all-optical switching using slow light within a hollow fiber
• Single-Photon Switch based on Rydberg Blockade
• Vacuum-Induced Transparency
• Observation and measurement of "giant" dispersive optical non-linearities in an ensemble of cold Rydberg atoms
• Self-organization of atoms in a cavity field: threshold, bistability and scaling laws
• Self-Organization Threshold Scaling for Thermal Atoms Coupled to a Cavity
• Photonic properties of one-dimensionally-ordered cold atomic vapors under conditions of electromagnetically induced transparency
• Optical Bistability and Collective Behavior of Atoms trapped in a High-Q Ring Cavity
• Optical parametric oscillation with distributed feedback in cold atoms
• Steady-state, cavity-less, multimode superradiance in a cold vapor
• Tunable photonic band gaps with coherently driven atoms in optical lattices
• Opto-Mechanical Pattern Formation in Cold Atoms
• Observation of a red-blue detuning asymmetry in matter-wave superradiance
• High-order optical nonlinearity at low light levels
• Collective excitations and instability of an optical lattice due to unbalanced pumping
• Quantum memory in an optical lattice

Cited by in corpus (2)

• Spontaneous emergence of free-space optical and atomic patterns
• Transverse optical and atomic pattern formation