Emulating a Quantum Computer with an FPGA

While building real quantum computers still proves to be a difficult task, work has been done to design quantum computer emulators on classical computers. Numerous methods have been implemented to escape the exponential growth of time and resources required for emulation of a quantum system. Field-Programmable Gate Arrays (FPGAs) are often used to shift the exponential growth from time to hardware, as they allow for the creation of circuits that evaluate quantum gate operations in parallel rather than sequentially. Adapting a design from a recent paper [1], we have implemented a Verilog module, running on a Basys3 FPGA board, that can emulate 2 qubits with full generality or 3 qubits with the restriction that all gates and input states be purely real. This allows for constant-time emulation, with the only exponential growth coming during one-time synthesis of the maximum size module that fits on a given board. This simple emulator can be a valuable low-cost teaching tool for students wishing to experiment with small quantum circuits and elucidate the inner functionality of a quantum computer.

1. Pilch, J., Dugopolski, J. An FPGA-based real quantum computer emulator. J Comput Electron 18, 329–342 (2019).