IonQ is the largest quantum computing pure-play company in terms of revenue and market value.Quantum computing might just be the hottest ticket on the artificial intelligence (AI) train. Throughout 2025, shares of the Defiance Quantum ETF have gained nearly 40% -- almost double that of the Invesco QQQ Trust, which tracks the Nasdaq-100. Among the most popular quantum computing pure-play stocks is IonQ (IONQ +0.15%), whose shares have soared by 39% over the last year. While IonQ has quite a bit of momentum b ...