A engineered quantum system that mimics the discrete energy levels of a natural atom, used as a qubit.An artificial atom is a deliberately engineered quantum system that reproduces the key property of a natural atom: discrete, quantized energy levels. Unlike real atoms, which are fixed by nature, artificial atoms are built in the lab from solid-state materials or superconducting circuits, and their energy spacing can be tuned by design. This makes them ideal building blocks for quantum computers, where each artificial atom serves as a qubit — the quantum analogue of a classical bit.
The concept emerged in the 1990s with the development of quantum dots and superconducting qubits, notably by researchers such as Daniel Loss, David DiVincenzo, and the groups of Yasunobu Nakamura and Yuri Pashkin, who demonstrated the first superconducting qubit in 1999.
The discrete energy levels arise because the system confines electrons or other quantum excitations in a small region, forcing them into standing-wave patterns with specific allowed energies. In a superconducting artificial atom, for example, the 'atom' is a tiny circuit with a Josephson junction; the quantized states are the collective motion of Cooper pairs. By applying microwave pulses, one can drive transitions between these levels, exactly as light drives transitions in a real atom, and read out the state via the circuit's response.
Artificial atoms are the core of most current quantum processors, including those made by IBM and Google, and are also used in quantum memory and quantum communication experiments.
In a superconducting artificial atom, the 'atom' is about a micrometer across — roughly 10,000 times larger than a real atom — yet it still obeys the same quantum rules.

















