Flip chip integration on qubit chips
A quantum bit (qubit) flip chip assembly may be formed when a qubit it formed on a first chip and an optically transmissive path is formed on a second chip. The two chips may be bonded using solder bumps. The optically transmissive path may provide optical access to the qubit on the first chip.
1. A method for forming a quantum bit (qubit) flip-chip assembly, the method comprising:
forming a qubit on a first chip;
forming an optically transmissive path in a second chip; and
bonding the first chip to the second chip; and
wherein the optically transmissive path is located above the qubit.
2. The method of claim 1 , wherein the path has an aperture with a diameter large enough to allow for treatment of the qubit.
3. The method of claim 1 , wherein the optically transmissive path has an aperture of 100 microns or less.
4. The method of claim 1 , further comprising laser annealing the qubit by applying a laser through a surface of the qubit chip that is opposite the second chip.
5. The method of claim 1 , further comprising ion etching the qubit.
6. The method of claim 1 , wherein the forming the optically transmissive path comprises drilling, using a high-power laser beam, the second chip to form a through-hole in the second chip.
7. The method of claim 6 , wherein the etching comprises deep-reactive ion etching.
8. The method of claim 6 , wherein the etching comprises a chemical etch, and wherein the chemical etch is a tetramethylammonium hydroxide (TMAH) etch.
9. The method of claim 1 , wherein the forming the optically transmissive path comprises etching a through-hole in the second chip.
10. The method of claim 1 , wherein the second chip comprises a transparent substrate.
11. The method of claim 10 , wherein the transparent substrate is Magnesiumoxide (MgO).
12. A flip chip apparatus comprising:
a first chip comprising a qubit;
a second chip bonded to the first chip, wherein the first chip and the second chip are bonded by a plurality of solder bumps; and
wherein an optically transmissive path in the second chip provides for optical access to the qubit on the first chip.
13. The apparatus of claim 12 , wherein the second chip comprises a transparent substrate.
14. The apparatus of claim 13 , wherein the transparent substrate is sapphire.
15. The apparatus of claim 12 , wherein the optically transmissive path has a diameter large enough to allow for treatment of one or more of the plurality of qubits.
16. The apparatus of claim 12 , wherein the qubit is accessible for laser annealing via the optically transmissive path.
17. The apparatus of claim 12 , wherein the optically transmissive path of the second chip is aligned with the qubit on the first chip.
18. The apparatus of claim 12 , wherein the optically transmissive path is formed with a chemical etch.
19. The apparatus of claim 12 , wherein the optically transmissive path is formed using a high-power laser beam.
20. The apparatus of claim 12 , wherein the first chip is comprised of a transparent substrate.