A quantum qubit coupling structure is provided. The quantum qubit coupling structure includes a plurality of qubits and a variable capacitor electrically connected between the plurality of qubits to vary coupling constants of the plurality of qubits.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A multi-qubit coupling structure comprising: a plurality of qubits; and a variable capacitor electrically connected to the plurality of qubits, wherein the variable capacitor is configured to vary coupling constants of the plurality of qubits. 2. The multi-qubit coupling structure of claim 1, wherein the plurality of qubits are superconducting qubits formed by using superconducting materials. 3. The multi-qubit coupling structure of claim 2, wherein the plurality of qubits have a stack structure comprising: a first superconducting material layer; a second superconducting material layer; and a dielectric layer between the first and the second superconducting material layers. 4. The multi-qubit coupling structure of claim 1, wherein the variable capacitor comprises superconducting materials. 5. The multi-qubit coupling structure of claim 1, wherein the variable capacitor comprises: a first planar pattern; a second planar pattern; and an intermediate layer between the first and the second planar patterns, wherein the intermediate layer has a dielectric constant which varies based on an applied voltage. 6. The multi-qubit coupling structure of claim 5, wherein the intermediate layer is formed of at least one of ferroelectric materials and piezoelectric materials. 7. The multi-qubit coupling structure of claim 6, wherein the first and the second planar patterns are formed of superconducting materials. 8. The multi-qubit coupling structure of claim 7, wherein the first planar pattern, the second planar pattern, and the plurality of qubits are formed of the same superconducting materials. 9. The multi-qubit coupling structure of claim 5, wherein the first and the second planar patterns are formed of superconducting materials. 10. The multi-qubit coupling structure of claim 9, wherein the first planar pattern, the second planar pattern, and the plurality of qubits are formed of the same superconducting materials. 11. The multi-qubit coupling structure of claim 5, wherein the variable capacitor is electrically connected to the plurality of qubits via superconducting materials. 12. The multi-qubit coupling structure of claim 11, further comprising an electrode pattern configured to apply a voltage to the intermediate layer of the variable capacitor and the first planar pattern of the variable capacitor, formed on a substrate; a material layer, formed on the substrate, configured to cover the electrode pattern and the first planar pattern; an insulating layer, formed on the material layer; and at least one via-hole of a first via-hole and a second via-hole, wherein the first via-hole is formed in the material layer and the insulating layer and is configured to electrically connect a first qubit and the first planar pattern, and the second via-hole is formed in the insulating layer and is configured to electrically connect a second qubit and the second planar pattern, wherein the second planar pattern is formed on a portion of the material layer which corresponds to the first planar pattern, and a portion of the material layer which corresponds to an intermediate portion between the first and second planar patterns forms the intermediate layer, the plurality of qubits are formed on the insulating layer. 13. The multi-qubit coupling structure of claim 12, wherein the at least one via-hole is filled with the same superconducting materials as that of the plurality of qubits. 14. The multi-qubit coupling structure of claim 1, further comprising: a substrate; and an electrode pattern formed on the substrate in order to apply a voltage to the variable capacitor, 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. 15. The multi-qubit coupling structure of claim 14, further comprising a material layer formed on the substrate in order to cover the electrode pattern and the first planar pattern, 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. 16. The multi-qubit coupling structure of claim 15, further comprising an insulating layer formed on the material layer, wherein the plurality of qubits are formed on the insulating layer. 17. The multi-qubit coupling structure of claim 16, wherein the insulating layer covers the second planar pattern, and the first planar pattern is electrically connected to a first qubit from among the plurality of qubits through a first via-hole formed in the material layer and the insulating layer. 18. The multi-qubit coupling structure of claim 17, wherein the second planar pattern is electrically connected to a second qubit from among the plurality of qubits via a second via-hole formed in the insulating layer. 19. The multi-qubit coupling structure of claim 15, wherein the material layer is formed of at least one of ferroelectric materials and piezoelectric materials, and the first and the second planar patterns are formed of superconducting materials. 20. A multi-qubit coupling structure comprising: a plurality of qubits; and a variable capacitor electrically connected to the plurality of qubits, wherein the variable capacitor is a tunable superconducting capacitor configured to vary coupling constants of the plurality of qubits based on adjustment of a voltage applied to the variable capacitor.