The 56-qubit H2-1 quantum computer has obliterated the previous benchmark in ‘quantum supremacy,’ first set by Google in 2019.

A groundbreaking quantum computer has eclipsed a world record in “quantum supremacy,” outperforming Google’s Sycamore machine’s benchmark by a staggering factor of 100. Employing the advanced 56-qubit H2-1 quantum computer, researchers at Quantinuum conducted a series of rigorous experiments to evaluate the machine’s performance metrics and qubit integrity. Their findings were unveiled on June 4 in a study submitted to the arXiv preprint repository, though it has yet to undergo peer review.

### To Illustrate the Prowess of the Quantum Computer,

Quantinuum scientists utilized a renowned algorithm to quantify qubit noise levels, an indicator of error susceptibility. Quantum computers leverage the principles of quantum mechanics and qubit entanglement, enabling parallel computation where the states of interconnected qubits can instantaneously influence one another. In stark contrast, classical computers operate in a sequential manner.

Increasing the number of qubits in a system exponentially amplifies its computational power; experts forecast that future quantum computers will execute complex calculations within seconds—tasks that would take classical supercomputers millennia to resolve. The milestone where quantum computers surpass classical counterparts is termed “quantum supremacy,” but realizing this feat in practical applications necessitates a quantum computer with millions of qubits. Presently, the largest quantum machine comprises roughly 1,000 qubits.

The necessity for such an extensive number of qubits for achieving “quantum supremacy” lies in their intrinsic propensity for errors, thus requiring numerous qubits for error correction. Consequently, many researchers are pivoting towards developing more reliable qubits instead of merely augmenting their quantity in machines.

The team assessed the fidelity of H2-1’s output using the linear cross-entropy benchmark (XEB). XEB yields scores ranging from 0 (completely erroneous output) to 1 (error-free output), as elucidated by Quantinuum representatives. Google’s initial testing of its Sycamore quantum computer with XEB in 2019 showcased its capability to complete a computation in 200 seconds—a task that would have taken the then most powerful supercomputer 10,000 years. The Sycamore registered an XEB score of approximately 0.002 with its 53 superconducting qubits.

### In Contrast,

the new study, a collaboration between Quantinuum scientists and researchers from JPMorgan, Caltech, and Argonne National Laboratory, reported an XEB score of approximately 0.35. This signifies that the H2 quantum computer can produce error-free results 35% of the time.

“We are entirely committed to the pursuit of universal fault-tolerant quantum computers,” stated Ilyas Khan, Quantinuum’s chief product officer and founder of Cambridge Quantum Computing, in the announcement. “While our ultimate objective remains unchanged, recent months have evidenced remarkable advancements attributable to extensive research and investment over many years.”

### Quantinuum

had previously partnered with Microsoft to demonstrate “logical qubits” with error rates 800 times lower than physical qubits. The study, published in April, showcased that experiments with logical qubits exhibited an error rate of just 1 in 100,000, vastly superior to the 1-in-100 error rate of physical qubits, as noted by Microsoft representatives.

“These findings indicate that although the fundamental advantages of fault-tolerant quantum computers remain constant, their realization may occur sooner than initially anticipated,” Khan concluded.

This article was originally published on livescience. Read the original article.

**FAQs**

**What is quantum supremacy?** Quantum supremacy is the point at which a quantum computer can perform a calculation that is infeasible for a classical computer to complete within a reasonable timeframe.

**How does the H2-1 differ from previous quantum computers?** The H2-1 boasts enhanced qubit quality and stability, higher computational power, and significantly greater energy efficiency compared to its predecessors.

**Why is energy efficiency important in quantum computing?** Energy efficiency reduces operational costs and environmental impact, making quantum computers more viable for widespread use.

**What are the main challenges in achieving practical quantum computing?** The primary challenges include improving qubit reliability, developing effective error correction techniques, and integrating quantum systems.

**How will quantum computing impact everyday technology?** Quantum computing has the potential to revolutionize fields such as cryptography, artificial intelligence, drug discovery, and complex system simulations, significantly impacting technology and society.