Abstract: A quantum device is disclosed having an LC resonator circuit for performing qubit measurement or readout. The device comprises a silicon layer (601), a dielectric layer (603) disposed upon and forming a functional interface with the silicon layer (601), a first metallic region (614) disposed upon the dielectric layer 603, and a second metallic region (624) disposed upon the dielectric layer 603 and laterally separated from the first metallic region (614). The first and second metallic regions (614, 624) are arranged to be electrically connected such that a double quantum dot, forming a qubit having a first state and a second state, can be induced beneath the first and second metallic regions (614, 624) at the functional interface. The double quantum dot provides a capacitor C1 in the LC resonator circuit and the capacitance of the double quantum dot is dependent on the state of the qubit.

Abstract: Quantum information processing apparatus and methods are described. The apparatus comprises a device for defining a qubit and a reflectometry circuit for reading out a state of the qubit. The device comprises a semiconductor nanowire extending along a first direction having first and second obtuse or acute edges running along the first direction, gate dielectric overlying the first and second edges of the nanowire and a split gate running across a section of the nanowire in a second, transverse direction, the split gate comprising first and second gates overlying the first and second edges respectively. The reflectometry circuit comprises a resonator coupled to the first or second gate.

Abstract: Quantum information processing apparatus and methods are described. The apparatus comprises a device for defining a qubit and a reflectometry circuit for reading out a state of the qubit. The device comprises a semiconductor nanowire extending along a first direction having first and second obtuse or acute edges running along the first direction, gate dielectric overlying the first and second edges of the nanowire and a split gate running across a section of the nanowire in a second, transverse direction, the split gate comprising first and second gates overlying the first and second edges respectively. The reflectometry circuit comprises a resonator coupled to the first or second gate.