Qubit-optical-CMOS integration using structured substrates
View Patent ↗Techniques for the integration of SiGe/Si optical resonators with qubit and CMOS devices using structured substrates are provided. In one aspect, a waveguide structure includes: a wafer; and a waveguide disposed on the wafer, the waveguide having a SiGe core surrounded by Si, wherein the wafer has a lower refractive index than the Si (e.g., sapphire, diamond, SiC, and/or GaN). A computing device and a method for quantum computing are also provided.
1. A waveguide structure, comprising:
a wafer;
a waveguide disposed on the wafer, the waveguide comprising a silicon germanium (SiGe) core surrounded by silicon (Si), wherein the wafer has a lower refractive index than the Si, wherein the waveguide has a ring shape, wherein the waveguide comprises a resonator-based microwave-to-optical transducer; and
at least one quantum bit (qubit) disposed on the wafer.
2. The waveguide structure of claim 1 , wherein the wafer comprises a material selected from the group consisting of: sapphire, diamond, silicon carbide (SiC), gallium nitride (GaN), and combinations thereof.
3. The waveguide structure of claim 1 , further comprising:
a top electrode disposed on the waveguide.
4. The waveguide structure of claim 3 , wherein the top electrode has a crescent shape.
5. The waveguide structure of claim 1 , further comprising:
a bottom electrode disposed on a side of the wafer opposite the waveguide.
6. The waveguide structure of claim 1 , further comprising:
bias electrodes disposed on the wafer on opposite sides of the waveguide.
7. The waveguide structure of claim 1 , wherein the at least one qubit comprises:
a superconducting bottom electrode on an Si layer; and
a superconducting top electrode separated from the superconducting bottom electrode by an insulator.
8. The waveguide structure of claim 7 , wherein the Si layer is undercut beneath the superconducting bottom electrode such that the at least one qubit is suspended over the wafer.
9. The waveguide structure of claim 1 , further comprising:
at least one superconducting bus path between the waveguide and the at least one qubit.
10. The waveguide structure of claim 9 , further comprising:
at least one field effect transistor (FET) disposed on the wafer connecting the at least one superconducting bus path between the waveguide and the at least one qubit.
11. A computing device, comprising:
a waveguide structure comprising a wafer, and a waveguide disposed on the wafer, the waveguide comprising a resonator-based microwave-to-optical transducer having a silicon germanium core surrounded by silicon (Si), wherein the wafer has a lower refractive index than the Si;
quantum bits (qubits) disposed on the wafer;
superconducting bus paths between the waveguide and the qubits; and
field effect transistors disposed on the wafer connecting the superconducting bus paths between the waveguide and the qubits.
12. The computing device of claim 11 , wherein the wafer comprises a material selected from the group consisting of: sapphire, diamond, SiC, GaN, and combinations thereof.
13. The computing device of claim 11 , wherein each of the qubits comprises:
a superconducting bottom electrode on an Si layer; and
a superconducting top electrode separated from the superconducting bottom electrode by an insulator.
14. The computing device of claim 13 , wherein the Si layer is undercut beneath the superconducting bottom electrode such that at least one qubit is suspended over the wafer.