Abstract: A method for making a vertically arranged array of edge-emitting lasers comprises: obtaining semiconductor chips that are laser diodes or semiconductor optical amplifiers; coating each of the semiconductor chips with a thermally conductive dielectric material; bonding the semiconductor chips onto a carrier wafer, such that the semiconductor chips are vertically aligned; coating the semiconductor chips with an electroplating seed material; obtaining a body wafer having lithographically defined and passivated openings; positioning the body wafer and the carrier wafer to match the openings; electroplating a metal-containing material onto the seed material to fill open space; demounting the body wafer from the carrier wafer; etching excess material from the body wafer; and patterning metal regions in electrical contact with the semiconductor chips.

Abstract: The disclosed ion trap comprises a plurality of structurally continuous blades and a plurality of recessed control electrodes, wherein the plurality of structurally continuous blades includes at least two structurally continuous RF blades and at least two structurally continuous DC blades, wherein the recessed control electrodes are disposed on or within the structurally continuous blades, and wherein the ion trap is in a ring configuration. The ion trap enables fast readout of optical transitions using stationary laser beams and moving ions. This design fundamentally contrasts with traditional linear Paul traps that employ stationary ions and laser beams that are turned on or off. Because the RF and DC blades are structurally continuous, the trapping potential is continuous and harmonic. Instead of segmenting the blades as conventionally, segmented recessed control electrodes are utilized to reduce voltage noise that causes unwanted heating of the ions. Many benefits and commercial uses are described.

Abstract: A low-power, chip-scale atomic beam clock is provided that maintains high precision for at least one week at any practical temperature. In some variations, the invention provides a chip-scale atomic beam clock comprising: a micro-optical bench; an atom collimator configured to generate a collimated atomic beam via differential pumping through microchannels; a VCSEL configured to emit laser photons horizontally in the plane of the micro-optical bench; an in-plane lithographically defined diffraction grating configured to split the laser photons into a first photon beam and a second photon beam; in-plane lithographically defined mirrors configured to retroflect the photon beams; in-plane photodetectors configured to detect the photon beams after being retroflected, wherein the first photon beam and the second photon beam interrogate the collimated atomic beam in-plane with the micro-optical bench.

Abstract: In some variations, an interferometric frequency-reference apparatus comprises: an atom source configured to supply neutral atoms; a collimator configured to form a collimated beam of the neutral atoms; one or more probe lasers; and a Doppler laser configured to determine a ground-state population of the neutral atoms. Other variations provide a method of creating a stable frequency reference, comprising: forming a collimated beam of neutral atoms; illuminating the neutral atoms with first and second probe lasers; adjusting the frequencies of the first probe laser and second probe laser using Ramsey spectroscopy to an S?D transition of the neutral atoms; and determining a ground-state population of the neutral atoms with another laser. The interferometric frequency-reference apparatus may provide an optical frequency reference or a microwave frequency reference.

Abstract: In some variations, an interferometric frequency-reference apparatus comprises: an atom source configured to supply neutral atoms to be ionized; an ionizer configured to excite the neutral atoms to form ionized atoms; an ion collimator configured to form a collimated beam of the ionized atoms; probe lasers; and a Doppler laser configured to determine a ground-state population of the ionized atoms, wherein the atom source, the ionizer, and the ion collimator are disposed within a vacuum chamber. Other variations provide a method of creating a stable frequency reference, comprising: forming ionized atoms from an atomic vapor; forming a collimated beam of ionized atoms; illuminating ionized atoms with first and second probe lasers; adjusting the frequencies of the first probe and second probe lasers using Ramsey spectroscopy to an S?D transition of ionized atoms; and determining a ground-state population of the ionized atoms with another laser.

Abstract: In some variations, an interferometric frequency-reference apparatus comprises: an atom source configured to supply neutral atoms; a collimator configured to form a collimated beam of the neutral atoms; one or more probe lasers; and a Doppler laser configured to determine a ground-state population of the neutral atoms. Other variations provide a method of creating a stable frequency reference, comprising: forming a collimated beam of neutral atoms; illuminating the neutral atoms with first and second probe lasers; adjusting the frequencies of the first probe laser and second probe laser using Ramsey spectroscopy to an S?D transition of the neutral atoms; and determining a ground-state population of the neutral atoms with another laser. The interferometric frequency-reference apparatus may provide an optical frequency reference or a microwave frequency reference.

Abstract: In some variations, an interferometric frequency-reference apparatus comprises: an atom source configured to supply neutral atoms to be ionized; an ionizer configured to excite the neutral atoms to form ionized atoms; an ion collimator configured to form a collimated beam of the ionized atoms; probe lasers; and a Doppler laser configured to determine a ground-state population of the ionized atoms, wherein the atom source, the ionizer, and the ion collimator are disposed within a vacuum chamber. Other variations provide a method of creating a stable frequency reference, comprising: forming ionized atoms from an atomic vapor; forming a collimated beam of ionized atoms; illuminating ionized atoms with first and second probe lasers; adjusting the frequencies of the first probe and second probe lasers using Ramsey spectroscopy to an S?D transition of ionized atoms; and determining a ground-state population of the ionized atoms with another laser.