{"id":6360,"date":"2024-12-10T11:56:42","date_gmt":"2024-12-10T10:56:42","guid":{"rendered":"https:\/\/www.zsvltava.cz\/fyzika\/?p=6360"},"modified":"2025-12-10T12:08:09","modified_gmt":"2025-12-10T11:08:09","slug":"co-je-kvantova-vazba","status":"publish","type":"post","link":"https:\/\/www.zsvltava.cz\/fyzika\/?p=6360","title":{"rendered":"Co je kvantov\u00e1 vazba?"},"content":{"rendered":"

Kvantov\u00e1 vazba je nenulov\u00e9 p\u0159ekryt\u00ed (overlap) vlnov\u00fdch funkc\u00ed dvou r\u016fzn\u00fdch stav\u016f. To p\u0159ekryt\u00ed vytv\u00e1\u0159\u00ed mo\u017enost:<\/p>\n

– interference mezi stavy,
\n– p\u0159echodu mezi nimi (tunelov\u00e1n\u00ed),
\n– sd\u00edlen\u00ed energie nebo informace.<\/p>\n

Pokud je p\u0159ekryv nulov\u00fd, stavy jsou \u00fapln\u011b odd\u011blen\u00e9 a syst\u00e9m nikdy nem\u016f\u017ee p\u0159ej\u00edt z A do B.<\/p>\n

Jak vypad\u00e1 kvantov\u00e1 vazba v dvouj\u00e1mov\u00e9m potenci\u00e1lu (dv\u011b \u00fadol\u00ed a kopec mezi nimi)<\/h2>\n

M\u00e1me dv\u011b hlubok\u00e1 energetick\u00e1 minima:<\/p>\n

– stav A: proud doprava
\n– stav B: proud doleva<\/p>\n

Vlnov\u00e9 funkce v obou minimech jsou siln\u00e9, proto\u017ee oba stavy jsou stabiln\u00ed. Pod bari\u00e9rou je v\u0161ak mal\u00fd, ale nenulov\u00fd pr\u016fnik.<\/strong><\/p>\n

Co kvantov\u00e1 vazba zp\u016fsob\u00ed?<\/h2>\n

Pokud mezi dv\u011bma stavy existuje vazba, jejich energie se nerozt\u0159\u00ed\u0161t\u00ed do dvou odd\u011blen\u00fdch hladin, ale vytvo\u0159\u00ed dva spole\u010dn\u00e9 stavy:<\/p>\n

– symetrick\u00fd stav
\n– antisymetrick\u00fd stav<\/p>\n

Rozd\u00edl jejich energi\u00ed je p\u0159\u00edmo \u00fam\u011brn\u00fd velikosti vazby.<\/p>\n

Toto roz\u0161t\u011bpen\u00ed energie je p\u0159\u00edmo m\u011b\u0159iteln\u00fd d\u016fkaz kvantov\u00e9 vazby. V supravodiv\u00fdch qubitech (transmons, flux qubits) se toto m\u011b\u0159\u00ed p\u0159esn\u011b.<\/p>\n

Co vznikne d\u00edky vazb\u011b?<\/h2>\n

Kdy\u017e existuje kvantov\u00e1 vazba, syst\u00e9m m\u016f\u017ee mezi stavy A a B oscilovat (Rabiho oscilace).<\/p>\n

– vazba je \u201emost\u201c pod bari\u00e9rou,
\n– vlnov\u00e1 funkce m\u016f\u017ee proudit tam i zp\u011bt,<\/p>\n

rychlost oscilace z\u00e1vis\u00ed na velikosti vazby. Pokud je vazba nulov\u00e1, oscilace neexistuj\u00ed a syst\u00e9m z\u016fstane nav\u011bky ve stavu A.<\/p>\n

Co p\u0159esn\u011b znamen\u00e1 vazba v makroskopick\u00e9m supravodiv\u00e9m obvodu?<\/h2>\n

V supravodi\u010di nejsou propojeny jednotliv\u00e9 elektrony. Je propojen makroskopick\u00fd koherentn\u00ed stav, kter\u00fd obsahuje miliardy elektron\u016f.<\/p>\n

Jeho vlnov\u00e1 funkce:<\/p>\n

– je rozprost\u0159ena p\u0159es cel\u00fd obvod,<\/p>\n

– m\u00e1 dv\u011b minima (nap\u0159. dv\u011b mo\u017en\u00e9 orientace proudu),
\n– pod bari\u00e9rou se tyto dv\u011b makrostavy p\u0159ekr\u00fdvaj\u00ed,<\/p>\n

a to p\u0159ekryt\u00ed vytv\u00e1\u0159\u00ed makroskopickou kvantovou vazbu.<\/p>\n

D\u00edky existenci vazby je mo\u017en\u00e9:<\/p>\n

– makroskopick\u00e9 tunelov\u00e1n\u00ed,
\n– existence dvou hladin,
\n– superpozice makrostav\u016f (co\u017e je vlastn\u011b qubit).<\/p>\n

P\u0159edstavme si:<\/p>\n

– dv\u011b obrovsk\u00e1 \u00fadol\u00ed odd\u011blen\u00e1 horou,
\n– ka\u017ed\u00e9 \u00fadol\u00ed = jeden stabiln\u00ed makroskopick\u00fd stav,
\n– kvantov\u00e1 vlnov\u00e1 funkce = voda napl\u0148uj\u00edc\u00ed \u00fadol\u00ed do ur\u010dit\u00e9 hladiny.<\/p>\n

Pod horou existuje tenk\u00e1 podzemn\u00ed jeskyn\u011b, kter\u00e1 \u00fadol\u00ed spojuje. To je kvantov\u00e1 vazba. Nen\u00ed to tunelov\u00e1n\u00ed (to je proces p\u0159el\u00e9v\u00e1n\u00ed). Vazba je existence toho podzemn\u00edho propojen\u00ed.<\/p>\n","protected":false},"excerpt":{"rendered":"

Kvantov\u00e1 vazba je nenulov\u00e9 p\u0159ekryt\u00ed (overlap) vlnov\u00fdch funkc\u00ed dvou r\u016fzn\u00fdch stav\u016f. To p\u0159ekryt\u00ed vytv\u00e1\u0159\u00ed mo\u017enost: – interference mezi stavy, – p\u0159echodu mezi nimi (tunelov\u00e1n\u00ed), – …. <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[94],"tags":[95],"class_list":["post-6360","post","type-post","status-publish","format-standard","hentry","category-moderni-fyzika","tag-kvantova-fyzika"],"_links":{"self":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/6360","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6360"}],"version-history":[{"count":1,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/6360\/revisions"}],"predecessor-version":[{"id":6361,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/6360\/revisions\/6361"}],"wp:attachment":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6360"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6360"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6360"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}