Luke Mortimer Proves Doom Really Will Run on Anything with Quandoom — Targeting Quantum Computers

Quantum information student and developer Luke Mortimer has taken "can it run Doom" to a whole new level, by creating a version of the seminal first-person shooter that runs on a quantum computer — albeit one that far exceeds the size of any built today.

"It is a well-known fact that all useful computational devices ever created are capable of running Doom," Mortimer explains. "Despite decades of active research, there is yet to be developed a single practical use for quantum computers. This changes today, with the release of Quandoom, a port of the first level of Doom designed for a quantum computer, given as a single QASM file, using a mere 70,000 qubits and 80 million gates."

Released in 1993, Id Software's Doom revolutionized the first-person shooter industry — despite what by modern standards is a somewhat clunky "2.5D" engine in which the player character is entirely unable to look up or down. The company's decision to release said engine under an open-source license led to it being ported to a broad range of devices — with the question of "can it run Doom" having been answered for GPS receivers, thermostats, in-car entertainment systems, microcontrollers, toothbrushes, and even Doom itself.

All of these, however, have something in common: they're classical computing systems, under the hood, operating on the principle of binary computation. Mortimer's target is different: a quantum computer, in which binary bits are replaced by quantum bits or "qubits" — capable of being held in a superposition between its two base states. Quantum computers are claimed by those investing in their creation to hold the potential to perform certain types of computation, from physics simulations to cryptography, significantly faster than a classical computer — though the field is still in its infancy, and current-generation quantum computers have a very small number of bits.

Nobody is positioning quantum computers as replacements for traditional binary computers, as the two target very different workloads: just as a classical computer is bad at quantum computation, a quantum computer is bad at classical computation. That hasn't stopped Mortimer, though, and it's now possible to run a basic implementation of Doom on a quantum computer — or, rather, a future quantum computer: Mortimer's Quandoom requires a device with 70,000 qubits, more than 500 times the size of IBM's record-breaking Heron quantum processor and 175 times bigger than the triple-processor IBM Quantum System Two computer.

"Although such a quantum computer doesn't exist right now," Mortimer admits, "Quandoom is efficiently simulatable on a classical computer, capable of running at 10-20 fps [frames per second] on my laptop using the accompanying lightweight (150 lines of C++) QASM simulator. It will use about 5-6GB of RAM and take a while to load since it's a very large circuit file."

Quandoom, which implements part of the game's first level with basic wireframe graphics, is available on Mortimer's GitHub repository under the permissive MIT license, along with a suitable simulator.