Single pixel structured imaging through fog.

We describe the application of structured imaging with a single-pixel camera to imaging through fog. We demonstrate the use of a high-pass filter on the detected bucket signals to suppress the effects of temporal variations of fog density and enable an effective reconstruction of the image. A quantitative analysis and comparison of several high-pass filters are demonstrated for the application.

Free space quantum key distribution using modulating retro-reflectors.

Quantum key distribution (QKD) can be used to produce a cryptographic key whose security is guaranteed by quantum mechanics. The range of fiber-based QKD links is limited, by loss, to a few hundred kilometers, and cannot be used between mobile platforms. Free space QKD can, in principle, overcome these limitations.

Quantum memory in warm rubidium vapor with buffer gas.

The realization of quantum memory using warm atomic vapor cells is appealing because of their commercial availability and the perceived reduction in experimental complexity. In spite of the ambiguous results reported in the literature, we demonstrate that quantum memory can be implemented in a single cell with buffer gas using the geometry where the write and read beams are nearly copropagating. The emitted Stokes and anti-Stokes photons display cross-correlation values greater than 2, characteristic of quantum states, for delay times up to 4 μs.

Spatially resolved magnetometry using cold atoms in dark optical tweezers.

We use Faraday spectroscopy of atoms confined to crossed hollow beam tweezers to map magnetic fields over 3 millimeters with 200 micron resolution in a single trap loading cycle. The hollow beams are formed using spatial light modulation, and the trap location is scanned using acousto-optic deflectors. We demonstrate the technique by mapping a linear quadrupole magnetic field with 10 nT sensitivity.

Efficient excitation of the TE(01) hollow metal waveguide mode for atom guiding.

We demonstrate excitation of the azimuthally-polarized TE(01) cylindrical waveguide mode in hollow glass and metal waveguides with 780 nm light. Experimentally, we demonstrate formation of the vectorial vortex beams, and measure attenuation lengths of the TE(01) mode in hollow optical fibers with diameters of 50-100 microns. By silver-coating the inner walls of the dielectric fibers, we demonstrate a approximately 200% increase in the attenuation length.