We present measurements of superconducting flux qubits embedded in a three dimensional copper cavity. The qubits are fabricated on a sapphire substrate and are 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 intrinsic energy relaxation time in the 6-20μs range and a pure dephasing time comprised between 3 and 10μs. This significant improvement over previous works opens the way to the coherent coupling of a flux qubit to individual spins.
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© 2014 American Physical Society.