Multiqubit gates for generating entangled states

The standard approach for building quantum circuits is to use a universal gate set that contains single-qubit gates and at least one entangling two-qubit gate. This typically leads to a long sequence of gate operations, putting severe restrictions on the fidelity of the quantum circuit. Using generically multiqubit gates may offer an efficient alternative. We study the effectiveness of two types of multiqubit gates with auxiliary single-qubit gates in generating highly entangled multiqubit states: (i) Simultaneous exchange couplings between many spin qubits with tunable exchange interaction, (ii) multiqubit gate from a quantum data bus architecture where many qubits can be connected to a common data bus. We find that multiqubit gates can significantly reduce the depth of the required quantum circuits for entangled states.