Flux Qubits in Three-Dimensional Circuit-QED Architecture

In this work, we present measurements of superconducting flux qubits embedded in a three dimensional copper cavity. The qubits were fabricated on a sapphire substrate and were measured by coupling them inductively to an on-chip superconducting resonator located in the middle of the cavity. At their flux-insensitive point, all measured qubits reach an intrisic energy relaxation time comprised between 6 and 20 {\mu}s and a Ramsey dephasing time between 2 and 10 {\mu}s, a significant improvement over previous work.