Aralar\u0131nda Bilkent \u00dcnv. Fizik B\u00f6l\u00fcm\u00fc mezunu Mete Atat\u00fcre\u2019nin de bulundu\u011fu bir grup fizik\u00e7i, daha \u00f6nce imk\u00e2ns\u0131z oldu\u011fu belirtilen, tek bir \u0131\u015f\u0131k par\u00e7ac\u0131\u011f\u0131n\u0131n s\u0131k\u0131\u015fmas\u0131n\u0131 \u00f6l\u00e7\u00fcmlemeyi ba\u015fard\u0131. S\u0131k\u0131\u015ft\u0131rma, kuantum fizi\u011finin ilgin\u00e7 bir fenomenidir; \u0131\u015f\u0131\u011f\u0131n d\u00fc\u015f\u00fck-g\u00fcr\u00fclt\u00fcl\u00fc \u00f6zel bir formunu yaratarak k\u00fctle\u00e7ekim dalgalar\u0131 gibi zay\u0131f sinyalleri yakalamak i\u00e7in potansiyel teknoloji arz eder. I\u015f\u0131\u011f\u0131 s\u0131k\u0131\u015ft\u0131rman\u0131n standart y\u00f6ntemi, -tercihen- lineer olmayan kristal bir maddeye lazer at\u0131m\u0131 g\u00f6ndermek ve istenilen etkinin ortaya \u00e7\u0131kmas\u0131 \u015feklindedir. Beri yandan tek bir atomu \u00e7ok az miktardaki \u0131\u015f\u0131kla uyararak da benzer bir etkinin ortaya \u00e7\u0131kaca\u011f\u0131n\u0131 \u00f6ng\u00f6ren bir teori de 30 y\u0131ldan fazla s\u00fcredir varl\u0131\u011f\u0131n\u0131 s\u00fcrd\u00fcrmektedir. Teoriye g\u00f6re atomdan sa\u00e7\u0131lan \u0131\u015f\u0131k da benzer \u015fekilde s\u0131k\u0131\u015fmal\u0131d\u0131r. Ancak 1981 y\u0131l\u0131na kadar at\u0131lm\u0131\u015f sa\u011flam matematiksel temellerine ra\u011fmen, rezonans floresan\u0131n s\u0131k\u0131\u015ft\u0131r\u0131lmas\u0131 olarak bilinir, bu etkiyi deneysel olarak g\u00f6zlemlemek o denli zordur ki, bir kuantum fizi\u011fi kitab\u0131nda bunu \u00f6l\u00e7meye \u00e7al\u0131\u015fman\u0131n beyhude bir \u00e7aba oldu\u011fundan bahsedilmi\u015ftir.<\/p>\n
Bir grup fizik\u00e7i, Nature <\/em>dergisinde yay\u0131mlad\u0131klar\u0131 makalede, yar\u0131 iletken kuantum nokta(quantumdot) olarak bilinen yapay atomlar kullanarak \u0131\u015f\u0131k par\u00e7ac\u0131klar\u0131n\u0131n -fotonlar\u0131n- s\u0131k\u0131\u015fmas\u0131n\u0131 deneysel olarak g\u00f6stermeyi ba\u015fard\u0131. Geli\u015fmi\u015f optik ve \u00f6l\u00e7me teknolojilerinin nimetlerinden yararlanan \u00e7al\u0131\u015fma ekibi, sa\u00e7\u0131lan \u0131\u015f\u0131\u011f\u0131 g\u00f6zlemlemeyi ba\u015fararak, s\u0131k\u0131\u015fma etkisinin ger\u00e7ekle\u015fti\u011fini kan\u0131tlam\u0131\u015f oldu. Cavendish Laboratuvar\u0131 Fizik B\u00f6l\u00fcm\u00fc\u2019nden Mete Atat\u00fcre ve Cambridge \u00dcniversitesi\u2019nden bir meslekta\u015f\u0131n\u0131n liderlik yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fma hakk\u0131nda Atat\u00fcre \u015f\u00f6yle diyor: \u201cBu\u00a0 etkinin g\u00f6zlemi teori a\u00e7\u0131s\u0131ndan son derece \u00f6nemliydi, ancak \u015fimdiye dek ba\u015far\u0131lamam\u0131\u015ft\u0131; hatta kimine g\u00f6re de ba\u015farman\u0131n bir yolu yoktu. Biz bunu g\u00f6zlemlemeyi ba\u015fard\u0131k, \u00e7\u00fcnk\u00fc elimizde optik \u00f6zellikleri s\u0131radan atomlardan \u00e7ok daha iyi olan yapay atomlar mevcut. Atomlar sayesinde fotonlar\u0131n temel \u00f6zelliklerini incelemek i\u00e7in gerekli \u015fartlara ula\u015fabildik ve kuantum fizi\u011finin garip fenomeni ve foton hakk\u0131nda sahip oldu\u011fumuz t\u00fcm beklentilere ters olan tek bir foton d\u00fczeyince s\u0131k\u0131\u015fman\u0131n ger\u00e7ekten oldu\u011funu g\u00f6zlemledik.<\/p>\n Kuantum fizi\u011finin bir\u00e7ok olgusunda oldu\u011fu gibi, s\u0131k\u0131\u015fman\u0131n ard\u0131nda da \u015fa\u015f\u0131rt\u0131c\u0131 prensipler yat\u0131yor.<\/p>\n \u0130lk olarak \u0131\u015f\u0131k par\u00e7ac\u0131\u011f\u0131n\u0131n varl\u0131\u011f\u0131, ona e\u015flik eden elektromanyetik dalgalanmalar\u0131n varl\u0131\u011f\u0131n\u0131 da beraberinde getirir ve bu dalgalanmalar \u201cg\u00fcr\u00fclt\u00fc\u201d olarak tan\u0131mlan\u0131r. I\u015f\u0131k yo\u011funla\u015ft\u0131k\u00e7a g\u00fcr\u00fclt\u00fc artar; s\u00f6n\u00fckle\u015ftik\u00e7e g\u00fcr\u00fclt\u00fc azal\u0131r. Fakat belirli bir kuantum d\u00fczeyde durum garip bir \u015fekilde farkl\u0131la\u015f\u0131r: Vakum dalgalanmas\u0131 olarak adland\u0131r\u0131lan bu \u00f6zel durumda, \u0131\u015f\u0131k olmad\u0131\u011f\u0131nda bile elektromanyetik g\u00fcr\u00fclt\u00fc varl\u0131\u011f\u0131n\u0131 s\u00fcrd\u00fcr\u00fcr. Klasik fizi\u011fin \u0131\u015f\u0131k yoksa mutlak karanl\u0131k vard\u0131r g\u00f6r\u00fc\u015f\u00fcn\u00fc ortadan kald\u0131ran kuantum fizi\u011fi, bahsi ge\u00e7en dalgalanmalar\u0131n \u0131\u015f\u0131k olmasa bile var olaca\u011f\u0131n\u0131 s\u00f6yler.<\/p>\n \u201cD\u00fcz bir y\u00fczeye bakt\u0131\u011f\u0131m\u0131zda, bize ger\u00e7ekten d\u00fcz ve p\u00fcr\u00fczs\u00fcz g\u00f6z\u00fck\u00fcr. Ancak y\u00fczeye yeterince yakla\u015f\u0131rsak ger\u00e7ekten de d\u00fcz olmad\u0131\u011f\u0131n\u0131 g\u00f6r\u00fcr\u00fcz\u201d diyen Atat\u00fcre, \u201cayn\u0131 durum vakum titre\u015fimleri i\u00e7in de ge\u00e7erli. Kuantum d\u00fcnyas\u0131na indi\u011fimizde b\u00f6yle bir durumla kar\u015f\u0131la\u015f\u0131r\u0131z; ortamda foton yokmu\u015f gibi g\u00f6r\u00fcn\u00fcr, fakat yine de hi\u00e7bir \u015feyden biraz daha fazla \u015fey vard\u0131r\u201d diye ekliyor.<\/p>\n \u00d6nemli bir nokta da vakum titre\u015fimlerinin daima var olaca\u011f\u0131 ve g\u00fcr\u00fclt\u00fcye temel bir limit koyaca\u011f\u0131d\u0131r. M\u00fckemmel \u0131\u015f\u0131k kayna\u011f\u0131 olarak bildi\u011fimiz lazerler bile bu temel seviyede dalgalanma g\u00fcr\u00fclt\u00fcs\u00fc ta\u015f\u0131mak zorundad\u0131r. Ancak i\u015fler bu noktadan sonra daha da garip bir hal al\u0131yor. Do\u011fru kuantum durumlar\u0131nda, bahsi ge\u00e7en temel limit seviyesi daha da a\u015fa\u011f\u0131ya \u00e7ekilebilir. \u0130\u015fte hi\u00e7bir \u015feyden daha az ya da vakumdan d\u00fc\u015f\u00fck bu seviyeye fizik\u00e7iler s\u0131k\u0131\u015fma demektedir.<\/p>\n Cambridge\u2019de yap\u0131lan deneyde s\u00f6n\u00fck lazer at\u0131mlar\u0131, yapay atomlar\u0131 olan kuantum noktaya g\u00f6nderilerek atomu uyard\u0131 ve uyar\u0131lan atom da foton emisyonu(yay\u0131l\u0131m\u0131) yapmaya ba\u015flad\u0131. Normalde bu fotonik aktiviteye e\u015flik eden g\u00fcr\u00fclt\u00fcn\u00fcn vakum durumundan daha y\u00fcksek seviyede olmas\u0131 gerekir, ancak \u00e7ok zay\u0131f uyar\u0131lmalarda \u0131\u015f\u0131\u011fa e\u015flik eden g\u00fcr\u00fclt\u00fc vakum dalgalanmalar\u0131n\u0131n alt\u0131nda kal\u0131r.<\/p>\n Bunun sebebini a\u00e7\u0131klamak i\u00e7in y\u00fcksek derecede karma\u015f\u0131k kuantum fizi\u011fi gerekir. Ancak en temelde, bir par\u00e7ac\u0131\u011f\u0131n birbirine ba\u011fl\u0131 iki \u00f6zelli\u011fi oldu\u011fundan ve birinde yap\u0131lacak \u00f6l\u00e7\u00fcm\u00fcn di\u011ferini belirsizle\u015ftirece\u011finden bahseden Heisenberg\u2019in belirsizlik ilkesiyle do\u011frudan ilintili bir fenomendir.<\/p>\n Klasik fizi\u011fin h\u00e2kim oldu\u011fu d\u00fcnyada bu kural uygulanamaz. E\u011fer bir cisim hareket halindeyse konumunu ve momentumunu ayn\u0131 anda kolayl\u0131kla \u00f6l\u00e7ebiliriz. Ancak kuantum d\u00fcnyas\u0131nda konum ve momentum birbirleriyle ba\u011flant\u0131l\u0131d\u0131r. Konumu \u00f6l\u00e7meye \u00e7al\u0131\u015f\u0131rsak momentum belirsiz kal\u0131r; momentum \u00f6l\u00e7\u00fcld\u00fc\u011f\u00fcnde ise konum belirsizdir.<\/p>\n Deneylerinde bu ilkeden faydalanan ara\u015ft\u0131rmac\u0131lar neyin \u00f6l\u00e7\u00fcl\u00fcp neyin \u00f6l\u00e7\u00fclemeyece\u011fi aras\u0131nda bir d\u00fczen oturttular. Kuantum noktadan zay\u0131f lazer \u0131\u015f\u0131\u011f\u0131 sa\u00e7arak elektromanyetik alan\u0131n g\u00fcr\u00fclt\u00fcs\u00fc, vakum dalgalanma e\u015fi\u011fi alt\u0131ndaki son derece kesin ve d\u00fc\u015f\u00fck bir seviyeye indirgendi. Bunu yapabilmenin bedeli de Heisenberg ilkesi gere\u011fince elektromanyetik alan\u0131n di\u011fer \u00f6zelliklerinin \u00f6l\u00e7\u00fclememesi olacakt\u0131r. Bu da yine Heisenberg ilkesiyle tutarl\u0131 \u015fekilde hi\u00e7bir \u015feyden az seviyede g\u00fcr\u00fclt\u00fcn\u00fcn ortaya \u00e7\u0131kabilme olas\u0131l\u0131\u011f\u0131na kap\u0131 aralar.Belirsizlikle elektromanyetik alandaki hangi dalgalanmalar\u0131n \u00f6l\u00e7\u00fclebilece\u011fi bir grafi\u011fe d\u00f6k\u00fcl\u00fcrse ortaya bir \u015fekil \u00e7\u0131kar: Bir taraftaki belirsizlik azald\u0131\u011f\u0131nda, di\u011fer k\u0131s\u0131mlarda geni\u015flemektedir. Ortaya \u00e7\u0131kan bu bas\u0131k veya s\u0131k\u0131\u015fm\u0131\u015f \u015fekil de s\u0131k\u0131\u015fm\u0131\u015f \u0131\u015f\u0131\u011fa dair i\u015farettir.<\/p>\n Atat\u00fcre, \u00e7al\u0131\u015fman\u0131n temel amac\u0131n\u0131n tek bir fotonu bu \u015fekilde g\u00f6zlemlemek oldu\u011funu \u00e7\u00fcnk\u00fc daha \u00f6nce b\u00f6yle bir g\u00f6zlemin yap\u0131lamad\u0131\u011f\u0131n\u0131 vurgulayarak, \u201cYapt\u0131\u011f\u0131m\u0131z t\u0131pk\u0131 Pl\u00fcton\u2019a daha yak\u0131ndan bakmak ya da pentakuarklar\u0131 g\u00f6zlemlemek gibi. T\u00fcm bunlar\u0131n \u015fimdilik teknolojik kar\u015f\u0131l\u0131klar\u0131 yok, ancak as\u0131l amac\u0131m\u0131z zaten bildiklerimizi art\u0131rmak; bunlar\u0131 yap\u0131yoruz \u00e7\u00fcnk\u00fc insan olarak merakl\u0131 ve yeni ke\u015fifler yapmaya arzuluyuz. Bilim de en temelde budur zaten\u201d diye ekliyor.<\/p>\n Kaynaklar:<\/strong><\/p>\n – Schulte, CHH, et al. Quadrature squeezed photons from a two-level system. Nature (2015). DOI: 10.1038\/nature14868.<\/p>\n – http:\/\/www.cam.ac.uk\/research\/news\/scientists-squeeze-light-one-particle-at-a-time#sthash.wbBlGUZi.dpuf<\/p>\n","protected":false},"excerpt":{"rendered":" Aralar\u0131nda Bilkent \u00dcnv. Fizik B\u00f6l\u00fcm\u00fc mezunu Mete Atat\u00fcre\u2019nin de bulundu\u011fu bir grup fizik\u00e7i, daha \u00f6nce imk\u00e2ns\u0131z oldu\u011fu belirtilen, tek bir \u0131\u015f\u0131k par\u00e7ac\u0131\u011f\u0131n\u0131n s\u0131k\u0131\u015fmas\u0131n\u0131 \u00f6l\u00e7\u00fcmlemeyi ba\u015fard\u0131. S\u0131k\u0131\u015ft\u0131rma, kuantum fizi\u011finin ilgin\u00e7 bir fenomenidir; \u0131\u015f\u0131\u011f\u0131n d\u00fc\u015f\u00fck-g\u00fcr\u00fclt\u00fcl\u00fc \u00f6zel bir formunu yaratarak k\u00fctle\u00e7ekim dalgalar\u0131 gibi zay\u0131f sinyalleri yakalamak i\u00e7in potansiyel teknoloji arz eder. I\u015f\u0131\u011f\u0131 s\u0131k\u0131\u015ft\u0131rman\u0131n standart y\u00f6ntemi, -tercihen- lineer olmayan […]<\/p>\n","protected":false},"author":634,"featured_media":17000,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[177,19,26],"tags":[288,1085,1533,356],"class_list":["post-3534","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-140-sayi","category-bilim-gundemi","category-fizik","tag-fizik","tag-isik","tag-kuantum","tag-parcacik-fizigi"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t