Abstract: Qubit circuits having components formed deep in a substrate are described. The qubit circuits can be manufactured using existing integrated-circuit technologies. By forming components such as superconducting current loops, inductive, and/or capacitive components deep in the substrate, the footprint of the qubit circuit integrated within the substrate can be reduced. Additionally, coupling efficiency to and from the qubit can be improved and losses in the qubit circuit may be reduced.

Abstract: Qubit circuits having components formed deep in a substrate are described. The qubit circuits can be manufactured using existing integrated-circuit technologies. By forming components such as superconducting current loops, inductive, and/or capacitive components deep in the substrate, the footprint of the qubit circuit integrated within the substrate can be reduced. Additionally, coupling efficiency to and from the qubit can be improved and losses in the qubit circuit may be reduced.

Abstract: The performance of an electro-optic modulator depends in part on the capacitance, the inductance, the electric field distribution, and the signal insertion loss of a microwave transmission line that modulates the refractive index of a waveguide via the electro-optic effect. Conventional electro-optic modulators are typically unable to improve one of these properties without negatively affecting other properties, resulting in lower performance. These shortcomings may be overcome, in part, by the inclusion of capacitive structures to decouple these properties. The capacitive structure may include a fang and/or a hook to tune the capacitance and the electric field distribution without appreciably changing the inductance or the signal insertion losses.

Abstract: A vertically stacked coplanar transmission line structure for an IC (integrated circuit) is provided which has superior loss and reflection characteristics relative to conventional on-chip transmission line designs. A simple embodiment of the vertically stacked coplanar transmission line structure comprises a micro-strip pair of first and second vertically stacked coplanar conductors, each comprising a metal layer, a next metal layer down, and an intermediate connecting via layer in between the metal layer and the next metal layer down.