  Quantum coherence in solid-state systems has been demonstrated in
superconducting circuits and in semiconductor quantum dots. This has paved the
way to investigate solid-state systems for quantum information processing with
the potential benefit of scalability compared to other systems based on atoms,
ions and photons. Coherent coupling of superconducting circuits to microwave
photons, circuit quantum electrodynamics (QED), has opened up new research
directions and enabled long distance coupling of qubits. Here we demonstrate
how the electromagnetic field of a superconducting microwave resonator can be
coupled to a semiconductor double quantum dot. The charge stability diagram of
the double dot, typically measured by direct current (DC) transport techniques,
is investigated via dispersive frequency shifts of the coupled resonator. This
hybrid all-solid-state approach offers the potential to coherently couple
multiple quantum dot and superconducting qubits together on one chip, and
offers a method for high resolution spectroscopy of semiconductor quantum
structures.
