**(IBM.blog)** Five years ago, IBM researchers put first quantum computer on the cloud, allowing anyone to program a quantum computer without access to an academic research lab.

Today, IBM has over 325,000 users on the IBM Quantum platform, including 140+ organizations in the IBM Quantum Network. Thousands of developers run two billion quantum circuits on IBM Quantum systems daily with the help of open source Qiskit software development kit. Together, our users have published more than 500 papers based on research conducted on IBM Quantum systems.

In addition to IBM’s quantum computer anniversary, May 2021 marks two important anniversaries in quantum computing. Forty years ago, a group of scientists gathered at the Physics of Computation conference jointly organized by MIT and IBM, where they laid the foundation of quantum computing.

To commemorate this double anniversary, IBM is presenting the IBM Quantum Challenge 2021. IBM has prepared five quantum programming exercises, each representing a milestone from quantum computing history from 1980 until today, while highlighting key features of Qiskit and IBM Quantum systems.

These milestones represent some of the most important advances in the field. The challenge begins with a problem about Tomasso Toffoli’s 1980 introduction of Toffoli gate, then poses problems surrounding Shor’s 1994 algorithm and 1995 introduction of quantum error correction. Finally, it tackles the modern history of quantum computing: a hardware-specific question as a nod to the 2007 introduction of superconducting transmon qubits, and a question applying the variational quantum eigensolver, an algorithm introduced in 2014.