A quantum computing cloud is a service that lets customers use a quantum computer over the internet, often on the same platform as ordinary AI tools and GPUs. Quantum computers are machines that use the rules of quantum physics to do certain calculations. They are not faster at everything. For a few kinds of problem, such as simulating molecules and some search and optimisation problems, they may one day be much faster than any ordinary computer.
An ordinary computer stores information in bits, each of which is 0 or 1. A quantum computer uses qubits. A qubit can be in a mix of 0 and 1 at the same time, and qubits can be linked so that the state of one depends on another. A program for a quantum computer is called a circuit. It is a list of operations applied to the qubits, followed by a measurement. The result of each measurement is partly random. So the same circuit is run many times, and the answer is read from the pattern of results.
Today's quantum computers are small and make many errors. They have tens or hundreds of qubits, and the qubits lose their state within a fraction of a second. Many machines also need cooling to near absolute zero. So almost nobody buys one. Instead, researchers and companies rent time on one through a cloud. The provider keeps the machine running and runs each customer's circuits in turn.
Here is a typical case. An engineering student at a university in Vadodara is studying how quantum computers might plan delivery routes. She writes a circuit for a small routing problem with 8 delivery stops, in Python, on the platform's website. The platform first runs it on a simulator, an ordinary computer program that imitates a quantum computer. Then it sends the circuit to a real quantum computer, which runs it 1,000 times. The results come back within an hour. She compares them with the answer from an ordinary program running on a GPU.
Putting quantum computers and AI tools on one cloud makes such comparisons easy. Most real jobs are a mix: the quantum part is small, and the rest runs on GPUs, often through a distributed computing framework. This is the one corner of model training and inference in which the hardware is not a GPU or another of the AI accelerators.
Do not confuse this with post-quantum cryptography. That is about new kinds of encryption that future quantum computers will not be able to break. A quantum computing cloud is about using the quantum computers that exist today.