Trapped-ion quantum computing uses individual atoms, stripped of one or more electrons to give them an electric charge, as qubits. These ions are held in place by electromagnetic fields in ultra-high vacuum chambers, where they form orderly chains that can be individually addressed and manipulated using laser beams. The internal energy levels of each ion encode the qubit states, and interactions between neighboring ions mediate entangling gates.
Trapped-ion systems boast several compelling advantages. They have the highest gate fidelities of any qubit technology — Quantinuum (formerly Honeywell Quantum Solutions) has demonstrated two-qubit gate fidelities above 99.8%. Ion qubits are naturally identical (every ytterbium-171 ion is exactly the same as every other), eliminating manufacturing variability. Coherence times of seconds or minutes far exceed those of superconducting qubits. IonQ, another leading trapped-ion company, has gone public and is deploying cloud-accessible quantum systems.
The primary challenge for trapped-ion systems is speed and scalability. Gate operations take microseconds — about 1,000 times slower than superconducting gates. Scaling beyond a few dozen ions in a single trap is difficult because long chains become unwieldy. Both IonQ and Quantinuum are pursuing modular architectures that connect multiple ion traps via photonic interconnects, aiming to scale to hundreds and eventually thousands of qubits. The trapped-ion approach is widely regarded as the leading contender for near-term high-fidelity quantum computing. For deeper coverage, see DeepTechIntel's quantum computing section.