Quantinuum sets new records for both gate fidelity and quantum volume – Quantum Computing Report

Quantinuum has always had a strategy of providing users with qubits that demonstrate the highest possible measure of qubit quality, as measured by both gate fidelity metrics and the quantum volume measure originally proposed by IBM. In fact, in 2020, they declared a goal to continue improving their machines’ quantum volume measurement by a factor of 10 times each year. And it must be recognized that they have continued to meet or exceed this goal each year.

Now, they have reached a new level of qubit-quality performance in their 20-qubit H1-1 processor, achieving a two-qubit gate fidelity measurement of 99.914% and a quantum volume measurement of 1,048,576 (or 2^twenty). The quantum volume benchmark was achieved with a circuit that used 20 qubits by successfully running a random circuit 20 layers deep. Although the circuit used in a quantum volume test would not be useful for a commercial application, the advantage of this benchmark is that it is difficult to “game” to show better results unfairly. It should also be noted that this same machine is also used daily at the service of end users. Therefore, it is not a special machine developed by engineering just to be used in these tests.

We must keep in mind that the company has maximized the capacity of the H1-1 processor, since that machine only contains 20 qubits. Another impressive result from Quantinuum’s testing is that they achieved very high consistency in performance across all qubits. In other quantum hardware implementations, there can be a wide range of qubit quality performance, some of which are good and some of which are not so good. In this latest test, each pair of qubits in this H machine achieved a two-qubit gate fidelity greater than 99.9%.

Quantinuum engineers achieved this result by implementing several improvements to the optical and laser systems within the machine. The original H1 processor was introduced in October 2020 with 10 qubits and a quantum volume level of 128 (or 2⁷). And the company has been rolling out many incremental updates over the years to improve qubit quality and double the number of qubits.

The next step in its development will be to take all the improvements and learnings from the H1 and apply them to the next generation H2 processor. The H2 currently supports 32 qubits, but the company intends to expand this in the future, as well as improve qubit fidelity metrics to levels similar to what they achieved with the H1.

This demonstration is one more step towards reaching a level of Quantum Advantage that can provide commercial benefits. Although many people are investigating error correction techniques, we should note that error correction becomes increasingly effective and efficient as the raw physical fidelities of qubits improve. Although there is still disagreement among quantum researchers about whether useful commercial applications will be able to run on an uncorrected NISQ-level machine, the chances of this also increase as raw qubit fidelities improve. Therefore, this development will be useful for use in both non-error-correcting NISQ implementations and more efficient error-correcting implementations on fault-tolerant machines.

We can’t describe this development as a Sputnik moment, but it is another step forward on the long road to providing high-quality quantum computing and is synergistic with research results from Quantinuum and Microsoft last month in demonstrating error-correcting circuits in their processors. For more information on this result, you can view a press release available on the Quantinuum website here. Additionally, for those who want to delve into the technical details, Quantinuum has published the technical data of its Quantum Volume test on GitHub here and also published the hardware specifications on GitHub here.

April 16, 2024