paper published today in the journal Physical Review A<\/a>, by Moe Z. Win and Peter L. Falb at MIT with Andrea Giani and Andrea Conti at the University of Ferrara. The team found a way of translating between quantum states of light and algebraic varieties (a mathematical structure from abstract algebra), making the analysis more manageable by reducing it to solvable mathematical equations.<\/p>\n\u201cQuantum systems can provide performance that is significantly better than classical counterparts,\u201d Win says, \u201cbut this doesn\u2019t come for free.\u201d To develop practical devices for producing and detecting different states, \u201cone needs to carefully engineer the quantum states in which they encode information.\u201d\u00a0<\/p>\n
Traditional computers typically use different voltages in a solid-state device to encode ones and zeros, while optical systems may use the presence or absence of a pulse of light. In quantum devices, the states might have to do with the spin state of a single atom, or the excitation level of a group of electrons.<\/p>\n
Win adds that \u201cwe have been studying how to design distinguishable quantum states, which translates directly into improved performance for sensing and communication.\u201d In the jargon of the field, they are improving the orthogonality \u2014 that is, the distinguishability \u2014 of different states.<\/p>\n
The particular kinds of states studied in this theoretical analysis had to do with energy levels of photons, or particles of light. Giani explains that they used an operation called photon variation. This can take two forms: photon addition, in which photons are excited to a higher energy state, or photon subtraction, in which photons are annihilated (i.e., removed from the system). These operations change the quantum state from Gaussian to non-Gaussian states; it\u2019s the non-Gaussian states that seem most useful, the team concluded.\u00a0<\/p>\n
\u201cThe domain of non-Gaussian states is quite big,\u201d Giani says, \u201cbut among them, we are looking into non-Gaussian states that are easier to implement with current technologies, because if we want to make the transition to the quantum world, we need to take into account realistic experimental challenges.\u201d<\/p>\n
Unlike some kinds of cutting-edge technologies being studied for possible quantum applications, Giani explains, \u201cthese kinds of photon-varied states have already been produced in the laboratory, and there is much interest in this kind of operation.\u201d<\/p>\n
These types of states are relatively new, Conti says, and so \u201cthere was a need for a theoretical characterization for these states,\u201d The theoretical characterization this team derived, based on underlying mathematical properties, makes it possible to design states with higher levels of distinguishability.\u00a0<\/p>\n
With this work, Win says, \u201cwe have a theory that gives us a blueprint to go design these non-Gaussian states, rather than just, \u2018try this and that, and let\u2019s hope they\u2019re somewhat distinguishable.\u2019 Our theory tells us exactly how to go about designing orthogonal non-Gaussian states.\u201d<\/p>\n
The findings result from the connection between the algebraic equations and the underlying physics, Win says, \u201cThat was the important connection between different disciplines \u2014 bringing algebraic geometry to the table.\u201d\u00a0<\/p>\n
\u201cThe equations to be solved for determining the orthogonality\u201d of the quantum states \u201chappened to be polynomial equations,\u201d Falb says. \u201cIt just happened that there was the appropriate mathematics to solve them.\u201d<\/p>\n
Now that the principles have been established through this work, implementation should be relatively straightforward, the researchers say. There already are some optical setups that can be used to implement these kinds of states.\u00a0<\/p>\n
\u201cIn principle,\u201d Giani notes, \u201cyou can just put the parameters that you find by solving these equations directly into your physical apparatuses and produce these kinds of states. I don\u2019t think this requires some more-advanced technology.\u201d\u00a0<\/p>\n
Conti adds that \u201cas soon as this paper is published, we hope that experimentalists can try these methods.\u201d<\/p>\n
But that\u2019s just the beginning, Win emphasizes. \u201cWe are getting momentum, and it\u2019s very exciting,\u201d he says. \u201cThe approach that we are taking here is to ask more general questions than just, \u2018here\u2019s a particular setup, how do you tune it to get a performance gain?\u2019 Rather, we\u2019re looking at a class of signal design problems, and then finding keys that really unlock these, so that hopefully the answer will not just be applied to only one particular setup, but something significantly broader.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Researchers around the world are racing to develop new quantum-based systems for sensing, communication, computing, and control that…\n","protected":false},"author":2,"featured_media":539019,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[271],"tags":[231492,18,19,17,231491,206281,231495,231494,231496,452,48688,751,231493,20806,133],"class_list":["post-539018","post","type-post","status-publish","format-standard","has-post-thumbnail","category-physics","tag-distinguishability-of-quantum-states","tag-eire","tag-ie","tag-ireland","tag-mit-idss","tag-mit-lids","tag-moe-z-win","tag-orthogonality","tag-peter-l-falb","tag-physics","tag-quantum-communications","tag-quantum-computing","tag-quantum-control","tag-quantum-sensing","tag-science"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/116762892568156545","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/539018","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=539018"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/539018\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/539019"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=539018"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=539018"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=539018"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}