Amid growing hopes for quantum technology, scientists have demonstrated the first proven quantum advantage in a photonic system. <\/p>\n
A new study shows how entangled light slashes the number of measurements needed to learn the noise of a quantum system.<\/p>\n
Researchers at the Technical University of Denmark (DTU) led the work with partners from the US, Canada, and South Korea. <\/p>\n
They used an optical setup that showed entangled light could identify the behaviour of a noisy quantum system far faster than classical approaches.<\/p>\n
\u201cThis is the first proven quantum advantage for a photonic system,\u201d said corresponding author Ulrik Lund Andersen, a professor at DTU Physics. \u201cKnowing that such an advantage is possible with a straightforward optical setup should help others look for areas where this approach would pay off, such as sensing and machine learning.\u201d<\/p>\n
At the heart of the study lies a long-standing challenge. When scientists want to understand a physical device, they must repeat measurements to determine its \u201cnoise fingerprint.\u201d For quantum devices, the problem intensifies. <\/p>\n
Quantum noise is built into measurements, and the number of required trials grows exponentially as systems get larger.<\/p>\n
\u201cWe built a process we could control and asked a simple question: Does entanglement reduce the number of measurements you need to learn such a system? And the answer is yes, by a lot,\u201d said Andersen.<\/p>\n
He added that the team learned the behaviour of their system in 15 minutes. A comparable classical method would take around 20 million years.<\/p>\n
Simple but powerful setup<\/p>\n
The experiment took place in the basement labs at DTU Physics. The team used standard optical parts running at telecom wavelengths. <\/p>\n
Even with ordinary losses in the setup, the system worked. That, they noted, showed the advantage came from the measurement method, not from ideal equipment.<\/p>\n
The setup relied on an optical channel where multiple light<\/a> pulses shared the same noise pattern. Two beams of light were squeezed until they became entangled. One beam probed the system while the other served as reference.<\/p>\n A joint measurement compared them in a single shot, cancelling much of the noise and extracting more information per trial than classical approaches.<\/p>\n That work suggested entangled light would deliver the needed leap, which the current experiment confirmed.<\/p>\n A step for quantum technology<\/p>\n The researchers stress they have not yet targeted a specific real-world system. Still, the breakthrough confirms a long-sought goal for quantum physics.<\/p>\n \u201cEven though a lot of people are talking about quantum<\/a> technology and how they outperform classical computers, the fact remains that today, they don\u2019t,\u201d said co-author Jonas Schou Neergaard-Nielsen, associate professor at DTU Physics. \u201cSo, what satisfies us is primarily that we have finally found a quantum mechanical system that does something no classical system will ever be able to do.\u201d<\/p>\n