IonQ’s new barium systems demonstrate industry-leading qubit readout performance

(IonQ) IonQ has published results from its new barium-based quantum computer showing its superior state detection fidelity. The results reflect a 13x reduction in state preparation and measurement (SPAM) errors, a metric core to producing accurate and reliable quantum computers. On a per-qubit basis, IonQ has reduced these errors from 50 errors per 10,000 computations down to only 4 per 10,000 computations. In other words, IonQ’s barium qubits have brought the company from a 99.5% state detection fidelity up to an industry-leading 99.96%.
The accuracy of computing results is key for the continued adoption of quantum computing in industries ranging from finance to chemistry. Quantum computers experience errors in three ways: imperfect state preparation at the beginning of an algorithm; imperfect quantum logic gates while running said algorithm; or imperfect measurement in reading out results. For quantum computers to scale while maintaining accuracy, all three sources of error must be mitigated. State detection errors grow with every qubit added, meaning that as systems scale, improved state detection fidelity is increasingly critical for the computer to deliver accurate results to a user. Even assuming flawless quantum logic gates, an average SPAM fidelity of 99% would limit a system’s #AQ to around 100; with a SPAM fidelity of 99.96%, it would require roughly 2000 qubits before SPAM became the limiting factor.
With these results, IonQ furthers its technical lead with the best state detection fidelity among commercial quantum computing providers. This high fidelity state detection is also expected to lead to improvements in the algorithmic qubit capacity of IonQ’s upcoming barium systems.
“We have already proven that trapped ions yield more algorithmic qubits than any other quantum computer architecture,” said Professor Jungsang Kim, co-founder and Chief Technology Officer of IonQ. “Today’s announcement demonstrates that our new barium qubits are already paving the way for increased fidelity, adding state detection error reduction as another area where IonQ is clearly leading the field.”
In December, IonQ announced its plan to use barium ions as qubits in its systems, bringing about a wave of advantages it believes will enable advanced quantum computing architectures. The proposed benefits included “lower error rates, higher gate fidelity, and better state detection.” Today’s milestone reaffirms IonQ’s belief that use of barium would lead to better state detection and fewer errors and further validates IonQ’s expansion of its qubit arsenal to include barium.
Last month, IonQ announced a public-private partnership with Pacific Northwest National Lab (PNNL) that created a sustainable, perpetual source of barium qubits to power these systems, securing the supply chain for future barium systems.