AGOGO BIYU, ƘASASHE BIYU, BUGU ƊAYA

Agogunan atom na haske (optical atomic clocks) yanzu suna kaiwa rashin tabbas na juzu’i na 10⁻¹⁸ da ƙasa da haka — daidai da daƙiƙa guda da ya ɓace cikin shekaru biliyan talatin. Sun fi agogunan microwave na caesium da ke fayyace daƙiƙa a yau da sama da ninki ɗari, kuma ana sa ran sake fayyace daƙiƙa bisa agogunan haske. Amma kafin a zaɓi sabon ma’auni, dole ne a duba agogunan da juna.

Me ya sa agogo biyu iri ɗaya

Kwatanta agogunan da ke amfani da sauyin atom iri ɗaya — tsallakawa tsakanin matakan makamashi biyu na atom, wanda agogon ke ƙirga mitar haskensa — yana ba da gwaji bayyananne: rabon mitarsu (frequency) dole ne ya zama ɗaya daidai. An nuna irin wannan daidaito ƙasa da 10⁻¹⁷ kusan tsakanin tsarukan da aka gina a cibiya ɗaya kawai. Wani gangamin Turai na baya tsakanin waɗannan agogo biyu ɗin ya kasa kaiwa burin 5 × 10⁻¹⁸ da aka sanya kafin sake fayyacewar, saboda ƙarancin bayanai. Kuma kwatance tsakanin wasu agogunan da aka gina daban-daban sun bayyana saɓani da ya zarce rashin tabbas da suka bayyana nesa ba kusa ba — alamar tasirin da babu wanda ya lissafa.

Ion ɗaya, ɗakunan gwaji biyu

Agogo biyun suna kama ion guda ɗaya na ytterbium-171 kuma suna binciken wani sauyi siriri ƙwarai, “electric octupole” wanda yanayinsa na tashin hankali yake ɗaukar shekaru. Ɗaya agogon, NPL-E3Yb+3, yana National Physical Laboratory a Teddington, Birtaniya. Ɗayan, PTB-Yb1E3, yana Physikalisch-Technische Bundesanstalt a Braunschweig, Jamus. Sun bambanta a ƙirar tarkonsu, laser ɗinsu da aka daidaita, da hanyar da suke soke sauyin da hasken binciken kansa ke haifarwa.

An haɗa su ta hanyar sadarwar Turai ta wayoyin haske, waɗanda aka daidaita ta yadda kusan ba sa ƙara wani sauyi (drift) nasu: km 2,220, ta tashoshin isarwa uku a Faransa — Laboratoire de Physique des Lasers a Villetaneuse, Laboratoire Temps Espace a Paris Observatory, da Jami’ar Strasbourg. Tsakanin 18 ga Maris da 12 ga Afrilu 2025, ƙungiyar ta tattara kwanaki 12.6 na bayanai masu amfani; agogo biyun da hanyar haɗin sun yi aiki tare kashi 51% na lokaci.

Sakamakon

Rabon mitoci biyun ya fito 1.000 000 000 000 000 001 0, tare da rashin tabbas na 48 a lambobin ƙarshe: bambanci na 1.0 × 10⁻¹⁸ ± 4.8 × 10⁻¹⁸, wanda ya dace da sifili. Iyakar sanin marubutan, wannan shi ne kwatancen agogo na ƙasa da ƙasa na farko da ya gaza 5 × 10⁻¹⁸.

Kasafin kuskure, a raka’o’in 10⁻¹⁸ (kurakurai masu zaman kansu suna ɗan soke juna: ana haɗa su a matsayin tushen murabba’i na jimlar murabba’ansu, shi ya sa jimlarsu ta zama 4.8 ba 8.8 ba):

• agogunan kansu: 2.8, babban tasirin shi ne zafin da kewayensu mai zafin ɗaki ke fitarwa;
• hanyar haɗin wayar haske ta ƙasa da ƙasa: 0.9;
• ƙididdiga: 1.6;
• sauyin ja na relativity (relativistic redshift) tsakanin wurare biyun — gwargwadon yadda agogo ya fi hawa a filin nauyin Duniya, haka yake buga da sauri, kusan 1 × 10⁻¹⁸ a kowace santimita —, har da jan hankalin raƙuman ruwa (tides) mai canzawa: 3.5 — mafi girman ɓangare guda.

Wannan gyara na ƙarshe ya dogara da matsayin kowane agogo a cikin ƙarfin nauyin Duniya (gravity potential). Rashin tabbasinsa ya yi daidai da bambancin tsayi na ɗan sama da santimita 3 tsakanin agogo biyun.

Gwajin relativity a gefe

Wurare biyun suna nesa da juna, kuma juyawar Duniya tana ci gaba da juya layin da ke tsakaninsu. Idan saurin haske ya dogara da alƙibla — keta abin da masana kimiyyar lissafi ke kira Lorentz invariance — rabon mitar zai riƙa kaɗawa tare da kowace ranar taurari (sidereal day) — juyawa ɗaya ta Duniya dangane da taurari, awa 23 da minti 56. Babu irin wannan alama da ta bayyana. An taƙaita ma’aunin da ke auna wannan dogaro kan alƙibla kusan sau biyar da tsauri fiye da a baya. Af, ba tare da gyaran raƙuman ruwa ba, wata kaɗawa ta ƙarya ta bayyana, mai ƙarfin da za a iya ɗauka alamar wata sigina: karkacewar ma’auni (standard deviations) 2.6.

Bayanan sun kuma bayyana cewa wayar haske tana ƙara hayaniya: watsuwar ta fi faɗi da kashi 24% da rana fiye da da dare, wanda ya dace da hargitsin muhalli a tsawon hanyar haɗin.

Yanzu santimita na da muhimmanci

Saboda nauyi ne ya mamaye kuskuren, marubutan sun rubuta cewa kwatance mafi kyau za su buƙaci ingantaccen sanin ƙarfin nauyi a kowane wuri — ko kuma agogon da za a iya kai shi ɗayan wurin ba tare da ya rasa ƙwarewarsa ba.