Flux Qubits with Long Coherence Times for Hybrid Quantum Circuits

Understand

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 6-20 microseconds range and a pure dephasing time comprised between 3 and 10 microseconds.
• This significant improvement over previous works opens the way to the coherent coupling of a flux-qubit to individual spins.