Google claims major quantum computing breakthrough
Researchers say their technique for reducing error rates is a significant advance
Google researchers claim to have taken a major step towards using quantum computers for real-world applications, discovering a method to reduce the error rates inherent in present-day quantum devices.
The company asserts that this breakthrough is on par with its declaration three years ago that it had achieved "quantum supremacy."
Quantum computers work in a fundamentally different way to classic computers, using qubits (quantum bits) as the basic building blocks of computing.
Unlike regular binary digits (bits) that store information as either a 0 or 1, qubits can store a combination of both through superposition.
For a quantum computer to work properly, qubits have to remain "entangled" with each other, meaning that the state of one qubit instantaneously affects the state of another, even when they are physically separate.
However, the primary challenge with present-day quantum computers is their inability to generate meaningful outcomes due to the extreme sensitivity of qubits.
Even minor interferences such as stray light can trigger calculation errors, and the issue worsens as quantum computers expand in size, where errors can make the devices practically unusable.
Google says its Quantum AI researchers have, for the first time, experimentally proven that it is achievable to decrease errors by increasing the number of qubits, using an error-correcting technique called a surface code.
The researchers said their study illustrates the possibility of mitigating quantum errors by treating physical qubits as a group (one logical qubit) instead of addressing them individually.
Dr Hartmut Neven, engineering director at Google Quantum AI, led a research team that constructed a quantum computer featuring 72 qubits and subjected it to two different surface codes (error correction codes).
The first code was implemented on 49 physical qubits that constituted a logical qubit, while the second was only applied to 17 qubits.
The experiment indicated that the larger logical qubit created from 49 qubits delivered significantly better performance than the smaller one.
In a blog post, Sundar Pichai, CEO of Google, affirmed that this breakthrough marks a "significant shift" in the operational methodology of quantum computers.
"By encoding larger numbers of physical qubits on our quantum processor into one logical qubit, we hope to reduce the error rates to enable useful quantum algorithms," he said.
Neven said the study demonstrates that Google has surpassed a "break-even point," after which continued progress would yield consistent performance improvements, ultimately leading the company towards developing its first practical quantum computer.
According to the researchers, the breakthrough in error correction was achieved through enhancements that Google had implemented in every component of its quantum computer, including the quality of its qubits, control software, and the cryogenic equipment used to cool the computer to near-absolute zero.
Google identified this achievement as the second of six steps necessary to create a practical quantum computer.
The subsequent phase entails refining its engineering to a level where only 1,000 qubits are needed to create a logical qubit.
"With further improvements toward our next milestone, we anticipate entering the fault-tolerant regime, where we can exponentially suppress logical errors and unlock the first useful error-corrected quantum applications," Neven said.
"In the meantime, we continue to explore various ways of solving problems using quantum computers in topics ranging from condensed matter physics to chemistry, machine learning and materials science."
The research findings have been published in the journal Nature.