Insider Brief<\/p>\n
Researchers demonstrated that dissipation, typically a source of errors in quantum systems, can be engineered to generate and maintain steady-state entanglement between superconducting qubits. <\/p>\n
The team developed a technique called synthetic squeezing that accounts for real-world noise and hardware imperfections, allowing high-quality entanglement without physically transporting qubits in delicate quantum states. <\/p>\n
Researchers are working to extend the approach beyond two qubits, with potential applications in quantum networking, entanglement distillation and distributed quantum computing.<\/p>\n
Two qubits coupled to a unidirectional waveguide can be driven into an entangled steady state. (Wolfgang Pfaff)<\/p>\n
PRESS RELEASE \u2014 The inevitable leakage of energy and information from a quantum system into its surrounding environment is the enemy of quantum technology. Now, researchers have demonstrated that it can be exploited to generate entanglement \u2014 the \u201cresource\u201d that quantum technologies use to perform tasks inaccessible to standard, classical technologies.<\/p>\n
A collaboration between physicists at the University of Illinois Urbana-Champaign and the University of Chicago has realized a theoretical prediction in which an externally driven quantum system achieves entanglement through dissipation. While the original prediction relies on highly idealized settings, the researchers developed a new technique called synthetic squeezing to realize the phenomenon in a laboratory setting with a pair of superconducting qubits.<\/p>\n
Moreover, the generated entanglement is in a steady state, meaning that, in principle, it can be maintained indefinitely over arbitrarily large distances. The researchers believe that this technique holds promise as a more robust and reliable alternative to current methods of entanglement generation.<\/p>\n
\u00a0\u201cIn the past, generating entanglement has meant performing a set of operations of different parts of a system then transporting them away from each other,\u201d said\u00a0Wolfgang Pfaff<\/a>, Professor of Physics in the University of Illinois Urbana-Champaign Department of Physics, who led the Illinois part of the collaboration. \u201cAs you can imagine, it\u2019s in the transport stage where things go wrong and environmental noise spoils the carefully prepared properties. We\u2019ve shown that it\u2019s possible to bypass the transport stage altogether.\u201d<\/p>\n \u201cThis idea has attracted theoretical attention for a long time because it runs counter to our experience with quantum entanglement,\u201d said\u00a0Aashish Clerk<\/a>, Professor of Molecular Engineering in the University of Chicago Pritzker School of Molecular Engineering, who led the Chicago part of the collaboration. \u201cRather than preparing it at one instant and watching it decay, it emerges as the natural point of relaxation in this system. It\u2019s almost like having a \u2018refrigerator\u2019 that pumps out external influences to maintain entanglement instead of pumping out heat to maintain coldness.\u201d<\/p>\n This research was recently published in the journal\u00a0Physical Review X<\/a>, and it is featured as a viewpoint in\u00a0Physics<\/a>\u00a0magazine.<\/p>\n Quantum entanglement is a phenomenon where different parts of a system display correlations that cannot be explained using non-quantum means. Quantum information technology exploits these correlations to perform tasks that are otherwise impossible or impractical. Most experts believe that building this technology into realms where its true potential can be realized will require combining physically separated units. So, there needs to be a good way for units to share entanglement.<\/p>\n Current methods of distributing entanglement prepare different objects in one location then transmit them to different locations. While in transit, the objects experience external influences and unwanted noise that causes the entanglement to erode, a process called decoherence. Managing these effects has been one of the most significant barriers to realizing quantum technology with practical utility.<\/p>\n \u201cThe interesting question is whether we need to have this step of transport that is vulnerable to decoherence,\u201d\u00a0Pfaff said. \u201cCould we have remote entanglement without having to transport particles in delicate states?\u201d<\/p>\n Theorists have identified a way to achieve remote entanglement between separated objects using a construct known as cascading. A set of quantum objects such as atoms (or superconducting\u00a0qubits) is made to continuously absorb and emit light. Some of this light is dissipated into the surrounding environment. If external light is introduced in a manner that balances the dissipated light, then a steady state emerges. Carefully engineering this steady state can result in the atoms or qubits displaying entanglement.<\/p>\n \u201cEven though the overall system is in contact with an outside environment and is out of equilibrium, it naturally evolves towards a resting point in which select parts of it are entangled,\u201d Clerk said. \u201cWhat\u2019s more, the quantum particles never need to move. They just need the ability to communicate.\u201d<\/p>\n While cascaded quantum systems have been achieved, the quality of the entanglement is generally lower than other methods because of noise and hardware imperfections. The researchers introduced synthetic squeezing as a framework that accounts for these \u201creal-world\u201d effects, tuning the system so they do not matter.<\/p>\n \u201cI\u2019ve worked with cascaded quantum systems before, but it was by working with professor Clerk and his research group that we could realize this prediction of high-quality steady-state entanglement,\u201d\u00a0Pfaff said. \u201cTheir theoretical proposal of synthetic squeezing says that the idealized setting of the original model can be replicated by adjusting the right experimental settings. It reduces the problem to fine tuning in the lab.\u201d<\/p>\n Having demonstrated synthetic squeezing on a\u00a0two-qubit system, the Illinois and Chicago groups are now working to extend the process to multi-qubit systems. The researchers believe that this technique holds promise for networking quantum computers without the need to directly transmit quantum information through noisy, lossy channels.<\/p>\n \u201cThe work ahead is going to be figuring out how different protocols can be implemented on this kind of system and determining what, if any, advantage is to be gained by doing so,\u201d\u00a0Pfaff said.<\/p>\n \u201cOne especially exciting route for us is entanglement distillation,\u201d Clerk added. \u201cRight now, the degree of entanglement we can achieve is quite good, but it\u2019s still below the theoretical limit. There are protocols in which a collection of\u00a0qubits with low entanglement can be combined so a few of them have a very high degree of entanglement. Such a protocol would let us start doing actual quantum computing operations with this system.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Insider Brief Researchers demonstrated that dissipation, typically a source of errors in quantum systems, can be engineered to…\n","protected":false},"author":2,"featured_media":733437,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[2302,90,56,54,55],"class_list":["post-733436","post","type-post","status-publish","format-standard","has-post-thumbnail","category-physics","tag-physics","tag-science","tag-uk","tag-united-kingdom","tag-unitedkingdom"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/733436","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=733436"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/733436\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/733437"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=733436"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=733436"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=733436"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}