This article is about the in-universe Supersomputer, If you are looking for the Code Wiki Supercomputer, see User:Wael.
The Lyoko Supercomputer is a quantum supercomputer designed to hold Lyoko, XANA, and countless actual individuals in its data at the same time. It was built by Franz Hopper for the purpose of destroying Carthage. During construction of the supercomputer, Franz Hopper discovered the time reversion feature and used it 2,546 times to complete work on the computer. Each time reversion doubles the processing power of the supercomputer, and by extension XANA. The supercomputer is powered by a uranium rod. The actual supercomputer is at the lowest level of the Factory where it spookily rises from a hatch with a kind of liquid in the center of the room. Should it short-circuit, XANA would be destroyed, but so would have Aelita if Team Lyoko wasn't already able to shut it down. This fact is what has kept Team Lyoko, especially Jeremie, from shutting it down in the second season. The computer has a monitoring port a few stories above, but only Jeremie and Aelita can fully understand its potential.
The idea of the supercomputer doubling in power with every Return to the Past is probably erroneous - if the supercomputer added a qubit with every return trip, then after Franz was done its data-processing power would be admirable (i.e. the level of a god) - most likely it takes multiple RTTPs to generate another qubit and increase the processing power of the system.
The subject of the fuel rod is also of debate - Uranium's half-life means the battery would not expire for hundreds of years, also Duncan and Jeremie would have been severly poisoned from being around both enriched Uranium and the depleted fuel rod - therefore it seems lead-210, a uranium isotope with a twenty-two year half-life, is the used fuel - it only gives off particle radiation, which cannot penetrate the perspex sleath of the fuel rods, and which could be converted to energy by the same process we see in the scanners when a body is destroyed and rebuilt during virtualization and materialization, respectively.
One possibility power source of the super computer is a device called a "radioisotope battery" which uses the power of decaying Plutonium-258 to give off aproximitally 500-600 megawats of power, this seems rather low for a such a powerful machine. Radioisotope batteries were used during the Cold War to power remote Soviet instalations and to power deep space satilites such as Voyeger 1 and Voyeger 2, the battery can produce enough power to keep a small computer going for 90 + years.
After XANA left the Lyoko Supercomputer in The Key, he began creating or infecting other supercomputers around the world and by doing this creating other virtual worlds (known as Replikas by Team Lyoko) across the network.
The Supercomputer is finally shut down for good in Echoes after the team decide that it is for the best even after XANA has been destroyed. It is shown as the Supercomputer lowes itself back into the depths of its pit that the hatch that covers it is engraved with the Eye of XANA (probably the only thing left on earth that will have the Eye).