Scientists have sent quantum signals over standard fiber-optic cables using the same connectivity that powers today\u2019s web, in what could be a major step towards a working quantum internet.<\/p>\n
In a study published Aug. 28 in the journal Science<\/a>, researchers used a custom-built quantum chip to package quantum data alongside a standard optical signal and transmit them over commercial infrastructure.<\/p>\n <\/p>\n The breakthrough marks the first time quantum data has been sent using Internet Protocol <\/a>(IP), the same communications standard that underpins today’s broadband networks. The results suggest that quantum communications could run on networks already in use, rather than needing dedicated infrastructure.<\/p>\n You may like<\/p>\n “Unlike earlier experiments that required isolated, lab-based setups or specialized infrastructure, this approach integrates quantum communication into real-world networks for the first time,” senior study author Liang Feng<\/a>, professor of materials science and electrical engineering at the University of Pennsylvania, told Live Science in an email.<\/p>\n “Our Q\u2011Chip enables control of quantum signals and classical signals, so they travel together over the same fiber\u2011optic cables, using standard internet protocols.”<\/p>\n Why can’t the internet send quantum data?<\/p>\n Quantum data is carried by qubits<\/a> \u2014 the basic units of quantum information. Unlike classical computer bits, which are represented as either 0 or 1, qubits can exist in a superposition<\/a> of both states.<\/p>\n Related: Scientists use quantum machine learning to create semiconductors for the first time \u2013 and it could transform how chips are made<\/a><\/p>\n Qubits can also become entangled<\/a>, meaning the state of one is symbiotically linked to the state of another, no matter how far apart they are. These properties enable quantum computers<\/a> to perform calculations far beyond the reach of conventional computers \u2014 in parallel rather than in sequence.<\/p>\n However, these same properties also make quantum data notoriously fragile. Quantum states<\/a> collapse when they’re observed or measured, making quantum information extremely difficult to work with. In classical internet, traffic is directed by routers that read and interpret information as it moves through the network. This can’t be done with quantum particles without destroying the very data being transmitted,because the superposition collapses as soon as it is observed.<\/p>\n How the Q-Chip works<\/p>\n The Q\u2011Chip, which stands for “quantum-classical hybrid internet by photonics”, tackles this challenge by pairing each quantum signal with a classical “header” \u2014 a data packet containing routing and timing information that\u2019s encoded into a fiber-optic laser pulse.<\/p>\n You may like<\/p>\n As this information travels through the network, it\u2019s inspected by routers \u2014 devices that direct internet traffic by reading packet information and forwarding it to the correct destination. Routers use the header to determine where the data should go and how to get it there.<\/p>\n By timing the classical and quantum signals to travel together in a synchronized pulse, the chip enables routers to read the header’s navigation information without interacting with or disrupting the quantum signal. This enables both to travel together via standard IP protocols.<\/p>\n While researchers have previously demonstrated that quantum data can be transmitted over standard fiber-optic cables<\/a>, including alongside classical data in the same wavelength band<\/a>, this latest study marks the first time that quantum signals have been transmitted using standard IP on live, real-world infrastructure.<\/p>\n