{"id":867049,"date":"2026-10-01T12:34:10","date_gmt":"2026-10-01T12:34:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/us\/867049\/"},"modified":"2026-10-01T12:34:10","modified_gmt":"2026-10-01T12:34:10","slug":"alice-bob-demonstrates-new-approach-to-stabilizing-cat-with-dc-voltage-bias","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us\/867049\/","title":{"rendered":"Alice & Bob Demonstrates New Approach to Stabilizing Cat With DC Voltage Bias\u00a0"},"content":{"rendered":"

Insider Brief<\/p>\n

Alice & Bob and ENS Lyon demonstrated a voltage-driven approach to stabilizing cat qubits that could enable more compact quantum hardware with lower heat generation.<\/p>\n

The device achieved a two-photon exchange rate of 3 MHz without a microwave drive, exceeding previous microwave-driven cat-qubit couplers while suppressing an unwanted frequency effect.<\/p>\n

Adjusting the voltage enabled one-, two- and four-photon exchanges on the same chip, potentially supporting four-component cat qubits.<\/p>\n

PRESS RELEASE \u2014 Alice & Bob, a leader in fault-tolerant quantum computing, and the \u00c9cole Normale Sup\u00e9rieure de Lyon today announced a new and faster\u00a0approach to stabilising\u00a0cat-qubits in superconducting quantum systems\u00a0enabling more compact\u00a0designs that\u00a0generate less heat.\u00a0\u00a0<\/p>\n

Cat qubits, which store information in a microwave resonator, are stabilised\u00a0by a process that dissipates photons from the resonator into the environment\u00a0strictly in pairs. This process takes place in a component called a coupler. In Alice & Bob\u2019s current cat qubits, the coupler is driven by a carefully engineered microwave signal, an approach the company has refined over many years.\u00a0\u00a0<\/p>\n

In this new experiment, the researchers explored an alternative coupler. They drove the same kind of process using a steady voltage of about one millionth of a volt, with no microwave signal required. Key findings include:\u00a0<\/p>\n

\"Introducing<\/a>\"Introducing<\/a><\/p>\n

Faster than any pumped coupler:\u00a0The new coupler exchanged photons faster than any previous\u00a0pumped-drive cat-qubit coupler (two-photon exchange rate of\u00a03 MHz. The data suggests that the design could reach considerably higher rates.<\/p>\n

Several operations, one chip:\u00a0Changing only the voltage switched the device between exchanging photons one, two or four at a time (two-photon process at a bias of about 1.1 microvolts).<\/p>\n

Suppression of unwanted nonlinearity:\u00a0Usual cat stabilisation usually comes with an unwanted change of frequency with the number of photons, which is harmful to cat codes. This new strategy suppresses this parasitic effect.<\/p>\n

Photons seen leaving in pairs:\u00a0The team directly imaged the memory \u2018s state using Wigner tomography and saw photons being dissipated in pairs.\u00a0\u00a0<\/p>\n

Rather than replacing existing approaches, the new mechanism adds to the toolbox for building cat qubits, providing access to higher-order processes such as four-photon interactions. These could support the development of four-component cat qubits, which encode information across four coherent states.\u00a0Four-photon processes are very difficult to achieve with existing methods, but with this approach it can be realistically achieved.\u00a0<\/p>\n

\u201cThis new approach could support the development of four-component cat qubits, which encode information across four coherent states. Four-to-one photon processes are very difficult to achieve with sufficient strength, but dc-biasing junctions seem to be a viable approach to that goal,\u201d\u00a0said Benjamin Huard, Scientific Advisor, Alice & Bob and Professor at Ecole Normale Sup\u00e9rieure de Lyon.\u00a0<\/p>\n

The approach could also make future quantum computers simpler to build at scale. Voltage lines are compact, easy to wire, and produce little heat inside the ultra-cold refrigerators that quantum computers need.\u00a0<\/p>\n

The research was carried out at ENS Lyon in collaboration with Alice & Bob, with the findings published in a preprint in August 2026 (here<\/a>).\u00a0\u00a0<\/p>\n

Technical note\u00a0<\/p>\n

The device couples a high-quality \u201cmemory\u201d resonator to a lossy \u201cbuffer\u201d resonator through a SQUID biased with a dc voltage. A Cooper pair tunneling across the SQUID exchanges an energy 2eV with the circuit, so it is only allowed to tunnel if the SQUID\u2019s environment can absorb or supply exactly that energy.\u00a0\u00a0<\/p>\n

The bias voltage V is set to a value such that 2eV matches the energy difference between two memory photons and one buffer photon. Therefore, the tunneling of Cooper pairs makes the two-to-one photon swap between memory and buffer energetically allowed. Each tunneling event converts a pair of memory photons into a single buffer photon, which quickly leaks out of the buffer, resulting in an effective two-photon dissipation of the memory at a rate of up to 1.3 MHz.\u00a0\u00a0<\/p>\n

On the same device, researchers showed that the same technique can be used to activate one-to-one and four-to-one photon swaps.\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"Insider Brief Alice & Bob and ENS Lyon demonstrated a voltage-driven approach to stabilizing cat qubits that could…\n","protected":false},"author":2,"featured_media":867050,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[199,79],"class_list":["post-867049","post","type-post","status-publish","format-standard","has-post-thumbnail","category-physics","tag-physics","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/867049","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=867049"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/867049\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/867050"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=867049"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=867049"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=867049"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}