Quantum dot devices

1. A quantum dot device, comprising:

a quantum well stack;

first gates above the quantum well stack;

second gates above the quantum well stack; and

an insulator material between a gate metal of the first gates and a gate metal of the second gates, wherein the gate metal of the first gates is between the insulator material and the quantum well stack.

2. The quantum dot device of claim 1 , further comprising:

a spacer material between the gate metal of the first gates and the gate metal of the second gates.

3. The quantum dot device of claim 1 , further comprising:

a spacer material above gate metal of the second gates.

4. The quantum dot device of claim 1 , further comprising:

second gate metal stubs alternatingly arranged with the second gates.

5. The quantum dot device of claim 1 , further comprising:

a gate dielectric between the gate metal of the first gates and the quantum well stack.

6. The quantum dot device of claim 5 , wherein the gate dielectric continuously extends between the gate metal of the second gates and the quantum well stack.

7. The quantum dot device of claim 1 , further comprising:

a multiplexer coupled to the first gates.

8. The quantum dot device of claim 1 , further comprising:

parallel first gate lines extending away from the first gates.

9. The quantum dot device of claim 8 , further comprising:

parallel second gate lines extending away from the second gates in a direction perpendicular to the first gate lines.

10. The quantum dot device of claim 1 , further comprising:

a plurality of magnets above the second gates.

11. The quantum dot device of claim 1 , further comprising:

a hardmask above the gate metal of the first gates.

12. The quantum dot device of claim 1 , further comprising:

multiple hardmasks above the gate metal of the first gates.

13. The quantum dot device of claim 1 , wherein the first gates are arranged in electrically continuous rows extending in a first direction, and the second gates are arranged in electrically continuous rows extending in a second direction perpendicular to the first direction.

14. The quantum dot device of claim 1 , wherein the quantum dot device is a quantum computing device that includes:

a quantum processing device, comprising the quantum well stack, the first gates, the second gates, and the insulator material,

a non-quantum processing device, coupled to the quantum processing device, to control electrical signals applied to the first and second gates, and

a memory device to store data generated during operation of the quantum processing device.

15. A quantum dot device, comprising:

a quantum well stack;

a plurality of first gate lines in a first layer above the quantum well stack; and

a plurality of second gate lines in a second layer above the quantum well stack, the second layer being closer to the quantum well stack than the first layer; and

a gate dielectric between one of the first gate lines and each of two or more of the second gate lines,

wherein the first gate lines are arranged in electrically continuous rows extending in a first direction, and the second gate lines are arranged in electrically continuous rows extending in a second direction perpendicular to the first direction.

16. The quantum dot device of claim 15 , wherein:

the gate dielectric is a first gate dielectric,

the quantum dot device further includes a second gate dielectric, and

the each of the two or more of the second gate lines is between the second gate dielectric and the first gate dielectric.

17. The quantum dot device of claim 16 , wherein a portion of the first gate dielectric is in contact with a portion of the second gate dielectric.

18. The quantum dot device of claim 15 , further comprising an insulator material between the electrically continuous rows extending in the first direction and the electrically continuous rows extending in the second direction.

19. The quantum dot device of claim 15 , wherein the quantum dot device is a quantum computing device that includes:

a quantum processing device, comprising the quantum well stack, the first gates, and the second gates,

a non-quantum processing device, coupled to the quantum processing device, to control electrical signals applied to the first and second gates, and

a memory device to store data generated during operation of the quantum processing device.

20. A quantum dot device, comprising:

a quantum well stack;

a plurality of first gates above the quantum well stack; and

a plurality of second gates above the quantum well stack,

wherein, for at least a gate of the plurality of first gates, the gate is between a first nearest neighbor pair of second gates of the plurality of second gates, and the gate is between a second nearest neighbor pair of second gates of the plurality of second gates, the first nearest neighbor pair of second gates being nearest neighbors along a first direction, and the second nearest neighbor pair of second gates being nearest neighbors along a second direction, the second direction being different from the first direction.

21. The quantum dot device of claim 20 , wherein the second direction is perpendicular to the first direction.

22. The quantum dot device of claim 20 , wherein the quantum dot device is a quantum computing device that includes:

a quantum processing device, comprising the quantum well stack, the plurality of first gates, and the plurality of second gates,

a non-quantum processing device, coupled to the quantum processing device, to control electrical signals applied to the first and second gates, and

a memory device to store data generated during operation of the quantum processing device.