Electromagnetically insulated superconducting qubit device

1 . An electromagnetically insulated superconducting qubit device comprising an electrical conductor having a substantially planar face and an artificial magnetic conductor having a substantially planar face facing the face of said electrical conductor, and one or more qubits made on or in one of said electrical conductor and said artificial magnetic conductor, the dimensions of the elements forming the artificial magnetic conductor and the distance separating the face of said electrical conductor and the face of said artificial magnetic conductor being chosen so as to make an electromagnetic band gap structure which comprises the frequencies of said qubits, the artificial magnetic conductor comprising a substantially planar electrically conductive base from which a plurality of projections project in a direction substantially orthogonal to the electrically conductive base together forming a bed of nails, and the distance separating the face of said electrical conductor and the base of said artificial magnetic conductor at the base of the projections being substantially less than the effective speed of light between the face of said artificial magnetic conductor and the face of said electrical conductor divided by twice the highest frequency among said one or more qubits.

2 . The device according to claim 1 , wherein the projections are arranged substantially periodically in the plane of the electrically conductive base with a periodicity less than the effective speed of light between the face of said artificial magnetic conductor and the face of said electrical conductor divided by 8 times the smallest frequency among said one or more qubits.

3 . The device according to claim 2 , wherein the projections have a height substantially greater than the effective speed of light between the face of said artificial magnetic conductor and the face of said electrical conductor divided by 4 times the smallest frequency among said one or more qubits.

4 . The device according to claim 1 , wherein the periodicity of the projections varies by less than 50%.

5 . The device according to claim 1 , wherein said one or more qubits are made by a two-dimensional superconducting circuit.

6 . The device according to claim 5 , wherein the superconducting circuit comprises a silicon or aluminum oxide base which surface is etched.

7 . The device according to claim 1 , wherein said one or more qubits are made with bosonic-encoded three-dimensional harmonic resonators.

8 . The device according to claim 7 , wherein the three-dimensional harmonic resonators are made in said electrical conductor.

9 . The device according to claim 7 , wherein the three-dimensional harmonic resonators are made in the artificial magnetic conductor.

10 . The device according to claim 7 , further comprising a two-dimensional superconducting circuit arranged to control or measure said one or more qubits.

11 . The device according to claim 5 , wherein the superconducting circuit is disposed substantially against the face of said electrical conductor, substantially against the face of said artificial magnetic conductor or between them, occupying part or all of the space between them.

12 . The device according to claim 1 , wherein the electrical conductor is made of aluminum with a degree of purity greater than or equal to 99.99%, niobium, superconducting material or copper covered with a superconducting film such as aluminum, niobium, tantalum, titanium nitride or niobium nitride.

13 . A quantum computational unit characterized in that it comprises several devices according to claim 1 arranged one after the other along a length direction of the face of the electrical conductor.