IonQ vs. Rigetti Computing: Which Pure-Play Quantum Stock Actually Has the Technology Edge?

Two major players are competing to develop quantum computers: IonQ and Rigetti Computing. IonQ utilizes trapped-ion technology, while Rigetti opts for superconducting qubits. Trap-ion systems employ charged atoms held in place by electromagnetic fields, whereas superconducting qubits are tiny electrical circuits cooled to near absolute zero temperatures.

IonQ has shown an impressive 99.99% fidelity for 2-qubit gates, the fundamental operations in quantum computing. However, Rigetti Computing's 108-qubit Cepheus system boasts a median 2-qubit fidelity of 99.1%. While IonQ's accuracy is higher, the difference in performance narrows when considering overall system fidelity, with Rigetti's error rate being about 1.8 times greater.

Trapped-ion systems from IonQ offer all-to-all connectivity, allowing direct interaction between any qubits. This feature reduces the need for additional operations, or SWAP gates, that might be required in more limited connectivity systems like Rigetti's. However, Rigetti's superconducting qubits boast faster gate operations, taking approximately 60 nanoseconds compared to IonQ's 950 microseconds for 2-qubit gates.

To address increasing qubit counts, IonQ is developing the Superion 256 platform, targeting 256 qubits. Despite manufacturing 256-qubit processor chips, commercial delivery is expected in 2027. Error correction is another crucial area for IonQ, with experiments encoding 4 logical qubits using 18 physical qubits demonstrating breakeven performance. DARPA has advanced IonQ to Stage B of its Quantum Benchmarking Initiative, evaluating the company's development plan and technical risks.

Rigetti Computing's 108-qubit Cepheus system shows progress in building larger quantum computers but struggles to maintain accuracy as qubit counts increase. The company aims to develop a 1,000-qubit system with 99.9% 2-qubit fidelity and faster gate operations within three years. If Rigetti can achieve these milestones, it may narrow the gap with IonQ in the quantum computing race.