By The End Of 2028, At Least One Quantum Computing Vendor Will Announce A Machine With More Than 300 Fault-tolerant Logical Qubits.

Will A Quantum Computer With 300 Logical Qubits Be Announced By 2028?

A forecast from a major prediction market suggests a 58% probability that at least one major quantum computer manufacturer will publicly demonstrate a machine with over 300 fault-tolerant logical qubits before the end of 2028. This prediction is based on the rapid scaling of logical qubits seen in recent years, particularly by IBM.

What Is The Current State Of Logical Qubit Scaling?

The field has moved from noisy intermediate-scale quantum (NISQ) devices to early quantum error correction (QEC). In December 2024, Google's Willow chip was the first to demonstrate a surface code below the threshold. Then, in July 2026, IBM, alongside the University of Chicago, showcased 70 logical qubits performing a calculation that classical methods could not practically replicate. This represents a jump from 1 logical qubit in December 2024 to 70 by mid-2026.

Which Companies Are Leading The Race To 300 Logical Qubits?

The main players are IBM, Google, QuEra, Quantinuum, and IonQ. QuEra has publicly targeted 1,000 logical qubits by 2029, while IBM's qLDPC error correction approach requires far fewer physical qubits per logical qubit than the surface code, accelerating scale-up. IBM also announced a goal of 100,000 physical qubits by 2033, up from its 1,121-qubit Condor chip in 2023.

What Are The Main Risks And Counterarguments?

Quantum roadmaps have historically slipped, and the definition of a "logical qubit" varies across companies. A system with 300 logical qubits is still far below the thousands needed for cryptography-breaking, making this more of a milestone than a practical breakthrough. However, the competitive pressure and investment flow from IBM, Google, and QuEra make a 2028 announcement plausible. If achieved, it would mark the first time quantum computers hold a measurable advantage over classical supercomputers for commercial optimization and materials simulation.

Frequently Asked Questions

What Counts As A Verified Calculation With Logical Qubits?

Verification requires a peer-reviewed paper or an official company announcement demonstrating a computation using more than 300 logical qubits. The calculation must be presented as practically difficult or impossible for classical computers to replicate, as seen in IBM's July 2026 announcement with 70 logical qubits.

Why Is The 300 Logical Qubit Threshold Significant?

It represents a 4.3x scale-up over IBM's 2026 result within roughly 2.5 years. While not enough for cryptanalysis, it would enable quantum computers to tackle specific optimization and simulation problems beyond the reach of classical systems, marking a shift from laboratory experiments to engineering-relevant workloads.

Could This Milestone Be Delayed Beyond 2028?

Yes. Historical evidence shows quantum roadmaps frequently slip. For example, earlier projections for 100 logical qubits by 2025 were missed. The 58% probability reflects a balance between the exponential scaling trend and the engineering challenges of maintaining low error rates as system size grows. A delay to 2029 or 2030 remains entirely possible.

Sources: IBM announcement (July 2026), Google Quantum AI (December 2024), QuEra public roadmap (2025), University of Chicago press release (2026).