Quantum Entanglement of Two Flux Qubits Induced by an Auxiliary SQUID

We revisit a theoretical scheme to create quantum entanglement of two three-level superconducting quantum interference devices (SQUIDs) with the help of an auxiliary SQUID. In this scenario, two three-level systems are coupled to a quantized cavity field and a classical external field and thus form dark states. The quantum entanglement can be produced by a quantum measurement on the auxiliary SQUID. Our investigation emphasizes the quantum effect of the auxiliary SQUID. For the experimental feasibility and accessibility of the scheme, we calculate the time evolution of the whole system including the auxiliary SQUID. To ensure the efficiency of generating quantum entanglement, relations between the measurement time and dominate parameters of the system are analyzed according to detailed calculations.