One-step generation of cluster states in superconducting charge qubits coupled with a nanomechanical resonator

We present a scalable solid-state system in which the superconducting charge qubits are coupled with a nanomechanical resonator (NAMR) to achieve highly entangled cluster states, which are responsible for one-way quantum computing via single-qubit measurements. Since the NAMR can play the essential role of the data bus, the long-range interactions among the qubits can occur. Therefore, without using the interacting picture we can directly obtain the long-range Ising-like unitary operator U-z(lambda)=exp[i lambda S-z(2)] with S-z the collective spin operator in z direction and lambda a parameter, which is insensitive to the thermal state of the NAMR. Based on this unitary operator, a set of highly entangled cluster states can be produced by efficient one-step generation. Moreover, the robustness of the highly entangled cluster states with respect to unavoidable parameter variations is also demonstrated.