{"id":199,"date":"2005-04-15T08:48:12","date_gmt":"2005-04-14T22:48:12","guid":{"rendered":"http:\/\/michaelnielsen.org\/?p=199"},"modified":"2005-04-15T08:48:12","modified_gmt":"2005-04-14T22:48:12","slug":"cluster-state-quantum-computation","status":"publish","type":"post","link":"https:\/\/michaelnielsen.org\/blog\/cluster-state-quantum-computation\/","title":{"rendered":"Cluster-state quantum computation"},"content":{"rendered":"

One of my main areas of research interest for the past few years has been measurement-based<\/em> models of quantum computation. In the standard accounts of quantum computing, a quantum computer is presented as a device that gets its power by performing coherent manipulations of superpositions of computational states, before a final measurement step destroys the superposition, singling out a single computational state to be read out.<\/p>\n

Measurement-based quantum computing turns this picture on its head. In such a model, there are no coherent manipulations of superpositions. Instead, it’s just all measurements, all the time. In Debbie Leung’s memorable phrase, we compute by “pinging Nature”.<\/p>\n

I’ve just written a short pedagogical review<\/a> of one of these models, the so-called “one-way quantum computer”, or “cluster-state model” of quantum computation. A simple version of this model was recently implemented in the lab, as reported in Nature<\/em><\/a> by the Zeilinger group.<\/p>\n

The review is written to be accessible to anyone with a thorough grounding in basic quantum mechanics. The main part of the review is spent explaining what a quantum computer is, what the cluster state model is, and how clusters can be used to simulate an ordinary quantum computer. At the end, I also explain two new results: (1) a no-go theorem which, subject to some caveats (see paper), forbids us from obtaining the cluster experimentally by cooling a physical system to the ground state; and (2) a proof that clusters must be prepared in two or more dimensions if they are to be useful for quantum computing.<\/p>\n

The review was written for a festschrift in honour of Tony Bracken and Angas Hurst, two well-known Australian mathematical physicists. Tony was my fourth-year honours thesis advisor, for which he suggested a wonderful topic: whether there is any connection between sometimes-negative “probability” distribution functions, like the Wigner function, and the Bell inequalities. It was a great topic for a student, combining a fundamental physical aspect with beautiful mathematics, and requiring only a little background to get started.<\/p>\n","protected":false},"excerpt":{"rendered":"

One of my main areas of research interest for the past few years has been measurement-based models of quantum computation. In the standard accounts of quantum computing, a quantum computer is presented as a device that gets its power by performing coherent manipulations of superpositions of computational states, before a final measurement step destroys the… Continue reading Cluster-state quantum computation<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-199","post","type-post","status-publish","format-standard","hentry","category-3","entry"],"_links":{"self":[{"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/posts\/199","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/comments?post=199"}],"version-history":[{"count":0,"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/posts\/199\/revisions"}],"wp:attachment":[{"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/media?parent=199"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/categories?post=199"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/michaelnielsen.org\/blog\/wp-json\/wp\/v2\/tags?post=199"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}