Quantum's Shift to Quality

Path to Commercialization

If you’ve been watching the actions of key quantum industry players over the last year, there has been a noticeable shift. From quantity to quality. And why? To achieve a useful commercial machine, sooner.

The quantum technology industry is undergoing a pivotal shift from prioritizing the sheer number of qubits to emphasizing their quality, driven by the challenges of achieving practical, fault-tolerant quantum computing. This transition reflects advancements and strategic shifts in areas such as error correction, roadmaps, logical qubits, and coherence.

Image source: Brian Lenahan/Midjourney

Error Correction

• From Noise to Stability: Early quantum systems focused on increasing qubit counts despite their high error rates. However, the realization that noisy qubits limit computational usefulness has shifted the focus toward implementing robust quantum error correction (QEC) protocols.

• Fault-Tolerant Architectures: Techniques like surface codes, which require many physical qubits to represent a single logical qubit, depend on high-quality physical qubits with low error rates to achieve practical thresholds for fault-tolerance.

• The Quantum Error Correction Report 2024 (produced by Riverlane) states that

  “Quantum hardware companies are embracing QEC: almost two-thirds (66%) of companies are now actively implementing QEC or have a heavy focus on QEC as a differentiating element of their operation. This typically involves setting up an internal division or research group dedicated to QEC.”

  Riverlane goes on to say “QuOps (reliable Quantum Operations) are a good measure of quantum computing performance, but future machines need new metrics and application-specific benchmarks…within two to three years, we will arrive at the MegaQuOp (million QuOps) inflexion point when quantum computers will surpass the reach of supercomputers.”

Roadmaps

• Evolving Milestones: Industry roadmaps initially emphasized the race to larger qubit numbers (e.g., achieving 1000+ qubits). Now, they include milestones related to coherence times, gate fidelities, and the realization of logical qubits.

• Quality Metrics: Companies like IBM, Google, and IonQ increasingly report metrics like quantum volume and error rates in addition to qubit counts, recognizing that system-wide performance matters more than raw qubit numbers.

• IBM (who believes the future of computing is quantum centric) in 2024 shifted from a focus on the quantity of physical quits to error correction and. mitigation:

  “We will improve the quality and speed of quantum circuits to allow running 5,000 gates with parametric circuits…Qiskit Primitives with error mitigation will provide the foundation platform where algorithm and application developers can focus on the workflows and get the best quality out of the quantum hardware…Built-in error mitigation will automatically determine the best method to reduce the effect of noise. Transpiler services will optimally rewrite circuits for hardware, taking advantage of AI. Watson Code Assistant will help users write Qiskit code to program quantum systems.” IBM Roadmap

Logical Qubits

• The Logical Leap: Logical qubits, which are error-corrected units constructed from multiple physical qubits, have become the focus of the next stage in quantum hardware development. Creating even a single reliable logical qubit is a significant milestone, as it is foundational for building scalable quantum systems.

• Trade-Offs: The efficiency of constructing logical qubits depends on improving the quality of physical qubits to minimize the overhead in terms of the number of physical qubits required.

• Robert Sutor in a recent LinkedIn post differentiating the value of logical qubits if limited to error detection and not correction of such errors.

• In September, having previously argued that the key issue for noisy intermediate-scale quantum (NISQ) machines’ physical qubits are too noisy and error-prone, making them impractical for real-world applications, Microsoft announced “the best performing logical qubits on record and will provide priority access to reliable quantum hardware in Azure Quantum”.

Coherence

• Key to Quality: Coherence time, the duration over which qubits maintain their quantum state, is critical for performing meaningful computations. Improving coherence times reduces the computational error rate and directly impacts the effectiveness of error correction.

• Material and Design Innovations: Advances in materials, fabrication techniques, and system designs aim to enhance coherence, making quality improvements a top priority for hardware researchers.

• The Quantum Insider wrote in October about a significant advance in coherence (notwithstanding equally significant limitations), this time for quantum metrology with coherence duration of 1,400 seconds. Iterative progress.

Conclusion

This shift from quantity to quality is essential for realizing the ultimate goal of fault-tolerant quantum computers. It reflects a maturing industry that recognizes the complexities of quantum scaling and the need for a balanced approach. As coherence and gate fidelity improve, the industry will increasingly be defined not by how many qubits exist, but by how well they work together to solve real-world problems.

Brian Lenahan is founder and chair of the Quantum Strategy Institute, author of seven Amazon published books on quantum technologies and artificial intelligence. Brian’s focus on the practical side of technology ensures you will get the guidance and inspiration you need to gain value from quantum now and into the future. Brian does not purport to be an expert in each field or subfield for which he provides science communication.

Brian’s books are available on Amazon. Quantum Strategy for Business course is available on the QURECA platform.

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