Fiber-integrated micro-optical elements promise a scalable approach to photon collection and beam shaping for quantum information processing. Here, we demonstrate single-step micro-machining of micro-spherical, micro-spiral, and micro-axicon structures directly onto the core of single-mode optical fibers using focused-ion beam (FIB) machining with nanometer-scale precision. Atomic force microscopy reveals that micro-concave and micro-convex spherical surfaces achieve shape accuracies of
λ/50 and
λ/33 (at
λ=633~nm), respectively. Via optical characterization using a He-Ne laser (633~nm), we verify for the micro-spiral and -axicon structures the expected far-field donut beam patterns. Via Mach-Zehnder interferometry, we verify the azimuthal and radial phase structure of the light emitted from the spiral and axicon fibers, respectively. Surface metrology further shows that FIB processing introduces only a small increase in nanoscale roughness while preserving sub-nanometer RMS surface quality. The monolithically integrated fiber micro-optic elements demonstrated here enable broad use in quantum technology, for example, fiber micro-cavities for cavity quantum electrodynamics, beam shaping for neutral atom trapping, and the generation of structured light for free-space quantum network links.
Abstract We review recent experimental progress towards quantum information processing and precision force sensing using neutral atoms in micro traps. Microscopic potential structures as generated by optical or electronic microstructures (micro traps) allow for a versatile manipulation of quantum states of atoms and of ultracold atomic quantum gases. Most recent experimental results include the implementation of single‐qubit‐operations in both, optical and magnetic micro traps, as well as in the demonstration of matter‐wave interferometer using Bose‐Einstein condensates coherently split in micro traps.
This program was a theory/experiment collaboration focusing on the fundamental need for scalability in the development of quantum information processing. Theory and experiment were connected and interleaved at several levels. The theory objectives were 1) to develop new theoretical tools to enable the implementation of reliable quantum information processing in scalable systems and 2) to characterize the relations between quantum algorithms and architectures, between fault tolerance and architectures, between quantum and classical complexity classes, and to develop secure primitives for quantum cryptography. The experimental objectives were to develop scalable quantum component technology based on gas phase systems using atoms and light fields. Specific experimental goals were scalable implementation of universal quantum logic in optical lattices and achievement of deterministic control in atom/cavity systems.