Reducing dissipation and frequency noise in quantum devices using a local vacuum cavity
A device includes: a substrate including a superconductor quantum device, the superconductor quantum device including a superconductor material that exhibits superconducting properties at or below a corresponding critical temperature; a cap layer bonded to the substrate; and a sealed cavity between the cap layer and the substrate.
1. A method comprising:
providing a substrate comprising a quantum circuit device, the quantum circuit device comprising a superconductor material that exhibits superconducting properties at or below a corresponding critical temperature; and
bonding a cap layer to the substrate to form a sealed cavity between the cap layer and the substrate, wherein the sealed cavity comprises a vacuum.
2. The method of claim 1 , wherein the pressure within the sealed cavity is less than or equal to about 10 −6 Torr.
3. The method of claim 2 , wherein the pressure within the sealed cavity is less than or equal to about 10 −9 Torr.
4. The method of claim 1 , wherein bonding the cap layer to the substrate is performed at room temperature.
5. The method of claim 1 , wherein a surface of the cap layer is bonded directly to a surface of the substrate to form the sealed cavity.
6. The method of claim 1 , wherein the cap layer comprises a first superconductor layer, the substrate comprises a second superconductor layer, and bonding the cap layer to the substrate comprises bonding the first superconductor layer to the second superconductor layer.
7. The method of claim 6 , wherein each of the first superconductor layer and the second superconductor layer comprises aluminum.
8. The method of claim 1 , further comprising performing, prior to bonding the cap layer to the substrate, ion milling of a surface of the substrate, wherein the ion milled surface is exposed to the vacuum within the sealed cavity.
9. The method of claim 1 , further comprising etching, prior to bonding the cap layer to the substrate, a surface of the substrate with XeF 2 gas, wherein the surface is exposed to the vacuum within the sealed cavity.
10. The method of claim 1 , wherein the quantum device is within the sealed cavity.
11. The method of claim 1 , wherein the quantum device comprises a qubit, a co-planar waveguide, an inductor, or an interdigitated capacitor.
12. The method of claim 1 , wherein a surface of the cap layer that faces the sealed cavity comprises a getter layer.
13. The method of claim 12 , wherein the getter layer comprises aluminum (Al), titanium (Ti) or zirconium vanadium titanium (ZrVTi).