Quantum computing offers the promise of being the next big technological breakthrough after artificial intelligence (AI). The technology has drawn the interest of the U.S. government, which has been investing in the sector. Meanwhile, investors can buy the stocks of several public companies that are attempting to develop fault-tolerant quantum computers using a variety of different techniques. Five of the best-known pure plays in the space are IonQ (IONQ -2.34%), Quantinuum (QNT -6.32%), Rigetti Computing (RGTI -0.33%), Infleqtion (INFQ +3.54%), and D-Wave Quantum (QBTS -2.53%). Let's consider which of these quantum stocks looks like the best buy. IonQ and Quantinuum NYSE: IONQ Key Data Points All quantum computers are built around qubits, which are extremely sensitive to even the slightest external interference. As a result, their computations have high error rates. The error-reduction and error-correction problems are among the chief challenges faced by every company trying to make quantum computing practical. The two companies at the forefront of accuracy, though, are IonQ and Quantinuum. Both companies use trapped-ion technology: Each qubit in their computers is made out of an individual charged atom (aka, an ion). This method results in qubits that are more stable than qubits created using other techniques. The result is that IonQ has achieved 99.99% 2-qubit gate fidelity (a standard metric for quantum computing accuracy), while Quantinuum sits at 99.92%. The companies differ primarily in how they hold their qubits in place. IonQ uses a combination of lasers and microwave antennas built into its chips, while Quantinuum employs only lasers, arguing that microwave antennas slow computational speed too much. Quantinuum is known for its comprehensive software stack, while IonQ has been developing an entire quantum ecosystem, having made acquisitions in quantum sensing, networking, and satellite transmission. It is even in the process of acquiring quantum chip foundry