Coherent flux qubits for quantum annealing (Theory)

Quantum annealing aims at solving combinatorial optimization problems faster than classical computing with less sensitivity to errors compared to gate-based quantum computing with no error correction. Here, we present the first generation of coherent qubit devices, consisting of both uncoupled and coupled four-Josephson junction flux qubits. We aim at low persistent currents for increased coherence and a large shunting capacitance both for charge noise reduction and higher parameter reproducibility. The inductive qubit-qubit coupling is achieved with rf-squids and the readout is performed with dispersive interaction with coplanar resonators. These processors serve as testbeds for quantum annealing experiments. Future designs in the context of the European FET Open project AVaQus will be discussed.