1. A multi-qubit coupling structure comprising: a plurality of qubits; a variable capacitor electrically connected to the plurality of qubits; a substrate; and an electrode pattern formed on the substrate to apply a voltage to the variable capacitor, wherein the variable capacitor is configured to vary coupling constants of the plurality of qubits, wherein the variable capacitor comprises: a first planar pattern formed on the substrate; an intermediate layer formed on the first planar pattern and having a dielectric constant which varies based on an applied voltage; and a second planar pattern formed on the intermediate layer, wherein the multi-qubit coupling structure further comprises a material layer formed on the substrate to cover the electrode pattern and the first planar pattern, and wherein a portion of the material layer, which corresponds to an intermediate portion between the first and the second planar patterns, forms the intermediate layer.