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This early network lives on two nanofabricated chips in a lab, yet it hints at secure long-distance quantum<\/a> links.<\/p>\n Building a quantum internet<\/p>\n The work was led by Andrei Faraon, the William L. Valentine Professor of Applied Physics and Electrical Engineering at California Institute of Technology (Caltech<\/a>).<\/p>\n His research focuses on using tiny optical devices to connect single atoms that act as long-lived carriers of quantum information.<\/p>\n Long-term plans for a quantum internet imagine networks of devices that send fragile quantum states between cities and even continents.<\/p>\n That phrase means, a system that moves quantum<\/a> information securely across long-distances and could support new kinds of encryption and distributed computing.<\/p>\n In the Caltech experiment, each node is a tiny chip that hosts many ytterbium atoms acting as individual qubits, a tiny quantum bit that can be 0 and 1 together.<\/p>\n To share information, the nodes try to place selected qubits into shared quantum states so that measuring one reveals something about its partner.<\/p>\n This work introduces entanglement multiplexing, a strategy that uses many qubits in parallel so several entangled links can be created at once.<\/p>\n Multiplexing and entanglement<\/p>\n Previous experimental quantum links usually relied on one optically addressed qubit in each node, so every attempt to create entanglement ran by itself.<\/p>\n That design made the overall communication rate painfully slow because the system spent most of its time preparing and resetting a single microscopic memory.<\/p>\n \u201cThis is the first-ever demonstration of entanglement multiplexing in a quantum network of individual spin qubits,\u201d said Faraon. This method significantly boosts quantum<\/a> communication rates between nodes, representing a major leap in the field.<\/p>\n In experiments, the team sent photons from two-nodes to a central station and used detection events to decide which pair should become entangled.<\/p>\n These results, including higher entanglement rates from several ions per node, are presented in a recent paper<\/a> on the two-node network.<\/p>\n \u201cEntanglement multiplexing overcomes this bottleneck by using multiple qubits per processor, or node,\u201d he said.<\/p>\n \u201cBy preparing qubits and transmitting photons simultaneously, the entanglement rate can be scaled proportionally to the number of qubits,\u201d said Andrei Ruskuc of Harvard University<\/a>.<\/p>\n Rare earth atoms in tiny light traps<\/p>\n To build the nodes, the Caltech team doped crystals with a special kind of atom known as a rare earth ion, a class of elements whose inner electrons interact weakly with their surroundings.<\/p>\n Because those electrons sit deep inside each ion, rare earth crystals can preserve quantum information longer than other solid-state platforms at comparable temperatures.<\/p>\n One experiment<\/a> showed that a nanophotonic resonator in such a crystal can act as a chip-scale quantum memory for single photons.<\/p>\n In this setup, each node is carved into a nanophotonic cavity, a tiny structure that traps and guides light in a small region.<\/p>\n When a laser excites one embedded ytterbium ion, the cavity boosts its emission so the photon travels toward the central station.<\/p>\n Each node contains roughly twenty such ions, and tiny differences in the crystal environment give every one a slightly different optical color.<\/p>\n Those color differences once looked like a nuisance because photons with mismatched frequencies refuse to interfere in the right way to create entanglement.<\/p>\n Smart control for messy photons<\/p>\n The key trick in this work is a control method called quantum feed-forward control. That phrase means, changing later quantum steps based on detector timing.<\/p>\n During each attempt, detectors at the central station record when photons from the two-nodes arrive and which combination of sensors clicked.<\/p>\n The control system turns that timing pattern into rotations on the relevant ions so their shared state always has the desired entangled form.<\/p>\n Beyond simple pairs, the team also prepared a special three ion W state, an entangled pattern where one shared excitation spans several particles.<\/p>\n Such multipartite states are harder to create than pairs, yet they are useful for tasks like secret routing or distributing work among quantum<\/a> nodes.<\/p>\n The ability to make W states on demand with hardware that produces pairwise links suggests versatile network nodes rather than single-purpose devices.<\/p>\n Next quantum internet steps<\/p>\n Looking beyond this single experiment, theorists have outlined architectures for a quantum network that links many nodes using repeaters, memories, and light-based connections.<\/p>\n That phrase means, a collection of quantum devices linked by channels that carry entangled particles, and schemes for building such networks are surveyed<\/a> elsewhere.<\/p>\n Most earlier test bed links relied on one optically addressable qubit per node, which limited memory capacity and the rate of successful entanglement.<\/p>\n They showed that many distinguishable ions in one cavity can act as separate channels, hinting at on-chip repeaters built from the same hardware.<\/p>\n In this platform, simulations suggest that a single node could eventually host hundreds of useful qubits.<\/p>\n If engineers also convert the emitted photons to telecom wavelengths, signals from such nodes could travel many miles through optical fiber with moderate loss.<\/p>\n The study is published in Nature<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Engineers have taken another big step towards creating a quantum internet by linking two quantum processors so that…\n","protected":false},"author":2,"featured_media":363486,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[199,79],"class_list":{"0":"post-363485","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/363485","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=363485"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/363485\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/363486"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=363485"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=363485"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=363485"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}