Released in 1993, Doom has such modest system requirements by today’s standards that it runs on the most unexpected hardware: it could be a tiny screen built into the Backspace key, a Christmas tree decoration, a voxel display, another game, an artificial intelligence system, a smart lawn mower, or a standard one. Windows program. But not a quantum computer.
Image source: github.com/Lumorti/Quandoom
Developer Luke Mortimer from Barcelona published the Quandoom project on GitHub – he recreated the first level of the cult shooter to run on a quantum computer and came to the conclusion that there is no machine powerful enough to run it yet. But you can create an “effective simulation” of it on a laptop. Quandoom requires 70,000 qubits and 80 million logic gates to run. The most powerful quantum computer to date was built by Atom Computing, and it has 1225 qubits.
And this is not even the full version of the game. Quandoom’s adaptation of the first level alone features basic wireframe graphics, no music or sound, and enemies cannot move between rooms. But this is still too much for existing quantum computers. “Right now I’m still tweaking the engine code, but at the core I have 8000 lines of C++ functions that allow you to perform a number of reversible binary and arithmetic operations on quantum registers, for example, “flipIfLessThanOrEqualTo”, which reverses all qubits in a register if the value of another register is less than a given one. Everything is done in whole numbers. Using such functions, I wrote a small 3D engine and all the game logic,” Quandoom’s description says.