there were several quantum computers built by various organizations and companies worldwide. However, the exact number is difficult to determine, as the field of quantum computing is rapidly evolving, and new advancements and deployments are being made.
Some notable examples of organizations involved in quantum computing include IBM, Google, Microsoft, Intel, Rigetti Computing, D-Wave Systems, and many more. These companies have made significant progress in developing quantum computers with varying numbers of qubits and capabilities.
It's important to note that quantum computers are still in the early stages of development, and practical, large-scale quantum computers with thousands or millions of qubits are not yet available. The current quantum computers are primarily limited in terms of qubit count, error rates, and overall stability.
Given the fast-paced nature of quantum computing research and development, it is recommended to refer to up-to-date resources and news outlets for the latest information on the number of quantum computers in existence.