Experiments on Google’s 67-qubit Sycamore processor show that operations enter a “low-noise phase,” where calculations are complex enough to outpace supercomputers.
Quantum computers can beat the fastest classical computers in a specific area, according to groundbreaking experimental results. The Google Quantum AI team found that it is possible to reach a “complex and stable phase” with off-the-shelf quantum processing units (QPUs). This means that when quantum computers enter this low-noise phase, they can perform complex calculations faster than the fastest supercomputers. Alexis Morvan, a quantum computing researcher at Google, and colleagues published their findings on October 9 in the journal Nature.
“We are focused on developing practical applications for quantum computers that cannot be implemented on classical computers,” said a representative of Google Quantum AI. “This research is an important step in that direction. Our next challenge is to demonstrate a real-world application.”
The quantum bits (qubits) in a QPU rely on the principles of quantum mechanics to run calculations in parallel, whereas classical computer bits can only process data sequentially. The more qubits a QPU has, the more powerful it becomes. Because of the parallel processing capabilities, calculations that would take thousands of years on a classical computer can be completed in seconds on a quantum computer.
But qubits are susceptible to noise, meaning they are extremely jumpy and prone to malfunctioning when subjected to disturbances, roughly one in 100 qubits compared to one in a billion billion bits. Examples include environmental disturbances such as temperature changes, magnetic fields, or even radiation from space. The high error rate means that to achieve quantum supremacy, researchers need highly sophisticated error-correction technology or quantum computers with millions of qubits. Scaling up quantum computers is not easy, with the largest number of qubits in a machine currently being limited to around 1,000.
A new experiment conducted by Google scientists shows that quantum computers can withstand current noise levels and outperform classical computers on certain calculations. However, error correction is still needed when scaling up machines.
The team used a random sampling method called random circuit sampling (RCS) to test the reliability of a 2D superconducting qubit network, one of the most common types of qubits made from superconducting metals suspended at temperatures close to absolute zero. RCS is a measure of how well a quantum computer performs compared to a classical supercomputer.
The results of the experiment revealed that qubits can switch between the first phase and a second phase called the “low noise phase” by activating certain conditions. In the experiment, on Google’s 67-qubit Sycamore chip, scientists increased the noise, or slowing down the spread of quantum correlations. In the low-noise phase, the computations were complex enough that they concluded that quantum computers could outperform classical computers.
According to Live Science
