{"id":5270,"date":"2021-01-27T16:45:06","date_gmt":"2021-01-27T22:45:06","guid":{"rendered":"https:\/\/scottaaronson.blog\/?p=5270"},"modified":"2021-03-07T13:20:12","modified_gmt":"2021-03-07T19:20:12","slug":"research-by-others-proceeds-apace","status":"publish","type":"post","link":"https:\/\/scottaaronson.blog\/?p=5270","title":{"rendered":"Research (by others) proceeds apace"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">At age 39, I already feel more often than not like a washed-up has-been in complexity theory and quantum computing research.  It&#8217;s not intelligence that I feel like I&#8217;ve lost, so much as two other necessary ingredients: <em>burning motivation<\/em> and <em>time<\/em>.  But all is not lost: I still have students and postdocs to guide and inspire!  I still have the people who email me every day&#8212;journalists, high-school kids, colleagues&#8212;asking this and that!  Finally, I still have this blog, with which to talk about all the exciting research that <em>others<\/em> are doing!<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Speaking of blogging about research: I know I ought to do more of it, so let me start right now.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Last night, Renou et al. posted a striking paper on the arXiv entitled <a href=\"https:\/\/arxiv.org\/pdf\/2101.10873.pdf\">Quantum physics needs complex numbers<\/a>.  One&#8217;s immediate reaction to the title might be &#8220;well duh &#8230; who ever thought it didn&#8217;t?&#8221;  (See <a href=\"https:\/\/scottaaronson.blog\/?p=4021\">this post of mine<\/a> for a survey of explanations for why quantum mechanics &#8220;should have&#8221; involved complex numbers.)  Renou et al., however, are interested in ruling out a subtler possibility: namely, that our universe is secretly based on a version of quantum mechanics with real amplitudes only, and that it uses extra Hilbert space dimensions that we don&#8217;t see in order to <em>simulate<\/em> complex quantum mechanics.  Strictly speaking, such a possibility can <em>never<\/em> be ruled out, any more than one can rule out the possibility that the universe is a classical computer that simulates quantum mechanics.  In the latter case, though, the whole point of Bell&#8217;s Theorem is to show that <em>if<\/em> the universe is secretly classical, then it also needs to be radically nonlocal (relying on faster-than-light communication to coordinate measurement outcomes).  Renou et al. claim to show something analogous about real quantum mechanics: there&#8217;s an experiment&#8212;as it happens, one involving three players and two entangled pairs&#8212;for which conventional QM predicts an outcome that can&#8217;t be explained using any variant of QM that&#8217;s both local and secretly based on real amplitudes.  Their experiment seems eminently doable, and I imagine it will be done in short order.<\/li><\/ul>\n\n\n\n<ul class=\"wp-block-list\"><li>A bunch of people from PsiQuantum posted a <a href=\"https:\/\/arxiv.org\/pdf\/2101.09310.pdf\">paper on the arXiv<\/a> introducing &#8220;fusion-based quantum computation&#8221; (FBQC), a variant of <a href=\"https:\/\/en.wikipedia.org\/wiki\/One-way_quantum_computer\">measurement-based quantum computation<\/a> (MBQC) and apparently a new approach to fault-tolerance, which the authors say can handle a ~10% rate of lost photons.  PsiQuantum is the large, Palo-Alto-based startup trying to build scalable quantum computers based on photonics.  They&#8217;ve been notoriously secretive, to the point of not having a website.  I&#8217;m delighted that they&#8217;re sharing details of the sort of thing they hope to build; I hope and expect that the FBQC proposal will be evaluated by people more qualified than me.<\/li><\/ul>\n\n\n\n<ul class=\"wp-block-list\"><li>Since this is already on social media: apparently, Marc Lackenby from Oxford will be <a href=\"https:\/\/www.math.ucdavis.edu\/research\/seminars\/?talk_id=6082\">giving a Zoom talk at UC Davis next week<\/a>, about a quasipolynomial-time algorithm to decide whether a given knot is the unknot.  A preprint doesn&#8217;t seem to be available yet, but this is a big deal if correct, on par with Babai&#8217;s quasipolynomial-time algorithm for graph isomorphism from four years ago (see <a href=\"https:\/\/scottaaronson.blog\/?p=2521\">this post<\/a>).  I can&#8217;t wait to see details!  (Not that I&#8217;ll understand them well.)<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>At age 39, I already feel more often than not like a washed-up has-been in complexity theory and quantum computing research. It&#8217;s not intelligence that I feel like I&#8217;ve lost, so much as two other necessary ingredients: burning motivation and time. But all is not lost: I still have students and postdocs to guide and [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"jetpack_seo_schema_type":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"{title}\n\n{excerpt}\n\n{url}","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"_wpas_customize_per_network":false,"jetpack_post_was_ever_published":false},"categories":[5,4],"tags":[],"class_list":["post-5270","post","type-post","status-publish","format-standard","hentry","category-complexity","category-quantum"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts\/5270","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5270"}],"version-history":[{"count":5,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts\/5270\/revisions"}],"predecessor-version":[{"id":5275,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts\/5270\/revisions\/5275"}],"wp:attachment":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5270"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5270"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5270"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}