System and method for scalable optical interconnect for quantum computing

#The present disclosure relates to interface systems used to interface a control system to a qubits plane of a quantum computing system, and more particularly to a readily scalable, all optical interface system for conducting signals to and from the qubits plane of the system.

#The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

#There are at least three critical issues associated with quantum computer packaging. The first issue is the thermal/signal issue. The delivery of electromagnetic control signals from the room-temperature region where they are generated to the qubits inside the refrigerator at mK temperatures requires careful thermal and electrical engineering. In the conventional architecture, wiring-whether low-frequency twisted pairs or high frequency coax must be thermalized at each temperature stage of the refrigerator to avoid excessive heating of the mixing chamber. The largest heat loads occur across the 300 to 3 K transition, and today's refrigerators can readily handle the heat loads of hundreds and even thousands of wires. For the 3 K to milli-K wires, superconducting NbTi can deliver the electrical signals faithfully, with minimal heating due to the direct thermal connection (phonons).

#The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

#Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

#FIG. 1 is a high level, side elevation view of an all optical interface system in accordance with one embodiment of the present disclosure, and illustrating four distinct implementations of the system being used in connection with a single electronic control system;

#Example embodiments will now be described more fully with reference to the accompanying drawings.

#Referring to FIG. 1, one embodiment of an all optical interface system 10 is shown in accordance with the present disclosure. In this example the system 10 includes one or more optical fiber ribbon cable assemblies 12 coupled to one of more optical waveguide structures, which in this example are formed by waveguide optical cubes 14. One side 12a of each of the optical fiber ribbon cable assemblies 12 is coupled to a circuit board 16a of an electronic control system 16, while the opposite side 12b of each optical fiber ribbon cable assembly is interfaced to a qubit package 18. In this example, each qubit package 18 has a grid of 128×128 (256 total) independent qubits, and each optical fiber ribbon cable assembly 12 has a plurality of separate optical fiber ribbon cables which collectively provide 512 separate optical fibers. One subplurality of 256 ones of the optical fibers of each optical fiber ribbon cable assembly 12 is used to form signal output paths or channels, and the remaining subplurality of 256 ones of the optical fibers are used as signal input paths or channels. Typically, the qubit package 18 comprises an area which is quite small, on the order of 5 mm×5 mm, and thus provides challenges when attempting to couple to each of the qubits of the qubit package using electrical conductors while still minimizing the thermal load imparted to the qubit package. The present system 10, through the use of the highly compact optical cubes 14 and the optical fiber ribbon cable assemblies 12, overcomes this significant limitation, as will be described further below.

#As noted above, of the 512 optical fibers making up each optical fiber ribbon cable assembly 12, 256 are associated with, or act as inputs to, each one of the 256 qubits (i.e., one optical fiber to each qubit) in the qubit package 18. The remaining 256 optical fibers of each optical fiber ribbon cable assembly 12 are associated with the outputs of the qubit package 18, that is, one optical fiber for each qubit output. In this manner independent input optical signals can be sent to each qubit of the qubit package 18, through the optical fiber ribbon cable assembly 12 and the optical cube 14. In addition, independent output signals, in the form of output optical signals, can also be sent by each qubit, through the optical cube 14 and the optical fiber ribbon cable assembly 12, to the electronic control system 16.