Waveguide filters comprising ridges disposed within a waveguide cavity for selecting electromagnetic signals within a frequency passband. An apparatus includes a waveguide filter comprising a waveguide cavity and a plurality of ridges disposed within the waveguide cavity. The apparatus is such that each of the plurality of ridges comprises a first side and a second side, and wherein the first side and the second side are disposed at a non-orthogonal angle relative to one other. The apparatus is optimized for fabrication using metal additive manufacturing techniques.

A passive device comprising a hollow waveguide including first and second wall structures extending in a guiding direction, an interconnecting base extending between the wall structures and an enclosure extending between the wall structures, the enclosure being located opposite the interconnecting base; and at least one array of coupled resonant structures enclosed inside the waveguide, the array being configured to provide coupled local resonators and a microwave or millimeter wave frequency passband for providing at least one selected microwave or millimeter wave signal, the array extending along the guiding direction and being located between the wall structures. Each resonant structure extends from the interconnecting base into the hollow waveguide to define a microwave or millimeter wave subwavelength resonant structure, and successive resonant structures are separated by a microwave or millimeter wave subwavelength distance. A resonance frequency of the resonant structures is less than a cut-off frequency of the waveguide.

A millimeter-wave resonator is produced by drilling a plurality of holes into a piece of metal. Each hole forms an evanescent tube having a lowest cutoff frequency. The holes spatially intersect to form a seamless three-dimensional cavity whose fundamental cavity mode has a resonant frequency that is less than the cutoff frequencies of all the evanescent tubes. Below cutoff, the fundamental cavity mode does not couple to the waveguide modes, and therefore has a high internal Q. Millimeter waves can be coupled into any of the tubes to excite an evanescent mode that couples to the fundamental cavity mode. The tubes also provide spatial and optical access for transporting atoms into the cavity, where they can be trapped while spatially overlapping the fundamental cavity mode. The piece of metal may be superconducting, allowing the resonator to be used in a cryogenic environment for quantum computing and information processing.

A millimeter-wave resonator is produced by drilling a plurality of holes into a piece of metal. Each hole forms an evanescent tube having a lowest cutoff frequency. The holes spatially intersect to form a seamless three-dimensional cavity whose fundamental cavity mode has a resonant frequency that is less than the cutoff frequencies of all the evanescent tubes. Below cutoff, the fundamental cavity mode does not couple to the waveguide modes, and therefore has a high internal Q. Millimeter waves can be coupled into any of the tubes to excite an evanescent mode that couples to the fundamental cavity mode. The tubes also provide spatial and optical access for transporting atoms into the cavity, where they can be trapped while spatially overlapping the fundamental cavity mode. The piece of metal may be superconducting, allowing the resonator to be used in a cryogenic environment for quantum computing and information processing.

Plasma jet assemblies utilizing evanescent mode cavity resonators, and methods of making the same and using the same, are described.

Plasma jet assemblies utilizing evanescent mode cavity resonators, and methods of making the same and using the same, are described.

A tunable microwave system includes at least two elements, each element being chosen from a propagating guide, an evanescent guide, a resonator, and at least one coupling device arranged between the two elements and configured to couple the two elements to each other, the coupling device having a holder having an aperture and having at least one elongate element the shape of which is elongate in a polarization direction contained in a plane of the aperture, the elongate element being securely fastened to the perimeter of the aperture at at least one end, the coupling device being configured to be rotatable about an axis substantially perpendicular to the plane of the aperture so as to modify a value of the polarization direction and so that the coupling between the two elements is dependent on the value of the polarization direction.

A tunable microwave system includes at least two elements, each element being chosen from a propagating guide, an evanescent guide, a resonator, and at least one coupling device arranged between the two elements and configured to couple the two elements to each other, the coupling device having a holder having an aperture and having at least one elongate element the shape of which is elongate in a polarization direction contained in a plane of the aperture, the elongate element being securely fastened to the perimeter of the aperture at at least one end, the coupling device being configured to be rotatable about an axis substantially perpendicular to the plane of the aperture so as to modify a value of the polarization direction and so that the coupling between the two elements is dependent on the value of the polarization direction.

A millimeter-wave resonator is produced by drilling a plurality of holes into a piece of metal. Each hole forms an evanescent tube having a lowest cutoff frequency. The holes spatially intersect to form a seamless three-dimensional cavity whose fundamental cavity mode has a resonant frequency that is less than the cutoff frequencies of all the evanescent tubes. Below cutoff, the fundamental cavity mode does not couple to the waveguide modes, and therefore has a high internal Q. Millimeter waves can be coupled into any of the tubes to excite an evanescent mode that couples to the fundamental cavity mode. The tubes also provide spatial and optical access for transporting atoms into the cavity, where they can be trapped while spatially overlapping the fundamental cavity mode. The piece of metal may be superconducting, allowing the resonator to be used in a cryogenic environment for quantum computing and information processing.

Waveguide cross sections designed for waveguide filters. An apparatus includes a waveguide cavity for propagating an electromagnetic signal, wherein the waveguide cavity is defined by a plurality of sidewalls. The waveguide cavity comprises an irregular hexagonal cross-sectional geometry that has a complex side, wherein the complex side comprises a first side and a second side connected to the first side, and wherein the first side and the second side of the complex side meet at a radiused edge.