Google’s Willow Quantum Computer Credit: Google Quantum AI
What sets quantum computers apart from classical machines? Recent experiments suggest that “quantum contextuality” may be a critical factor.
Quantum computers fundamentally differ from traditional systems by leveraging unique quantum phenomena absent in classical electronics. Their building blocks, known as qubits, can exist in a superposition state, representing two properties simultaneously, which are typically incompatible, or they can be interconnected through a phenomenon called quantum entanglement.
Researchers at Google Quantum AI have conducted several groundbreaking demonstrations using the Willow quantum computer, revealing that quantum contextuality is also significant.
Quantum contextuality highlights an unusual aspect of measuring quantum properties. Unlike classical objects, where attributes are stable regardless of measurement order, quantum measurements are interdependent.
This phenomenon has previously been explored in special experiments with quantum light, and in 2018, researchers mathematically proved its potential application in quantum computing algorithms.
This algorithm enables quantum computers to uncover hidden patterns within larger mathematical structures in a consistent number of operations, regardless of size. In essence, quantum contextuality makes it feasible to locate a needle in a haystack, irrespective of the haystack’s dimensions.
In our experiments, we scaled qubit numbers from a few to 105, analogous to increasing the haystack size. While the number of steps rose with additional qubits, Willow demonstrated superior noise and error management compared to an ideal theoretical quantum computer for the algorithm involved. Notably, it still required fewer steps than traditional computers would need.
Thus, quantum contextuality appears to confer a quantum advantage, allowing these computers to utilize their unique characteristics to outperform classical devices. The research team also executed various quantum protocols reliant on contextuality, yielding stronger effects than previous findings.
“Initially, I couldn’t believe it. It’s genuinely astonishing,” says Adan Cabello from the University of Seville, Spain.
“These findings definitively showcase how modern quantum computers are redefining the limits of experimental quantum physics,” states Vir Burkandani at Rice University, Texas, suggesting that a quantum computer, as a candidate for practical advantages, should accomplish these tasks to confirm its quantum capabilities.
However, this demonstration does not yet confirm the superiority of quantum technology for practical applications. The 2018 research established that quantum computers are more effective than classical ones only when using more qubits than those in Willow, as well as employing qubits with lower error rates, asserts Daniel Lidar at the University of Southern California. The next crucial step may involve integrating this new study with quantum error correction algorithms.
This experiment signifies a new benchmark for quantum computers and underscores the importance of fundamental quantum physics principles. Cabello emphasizes that researchers still lack a complete theory explaining the origins of quantum superiority, but unlike entanglement—which often requires creation—contextuality is inherently present in quantum objects. Quantum systems like Willow are now advanced enough to compel us to seriously consider the peculiarities of quantum physics.
Topics:
Source: www.newscientist.com
