Hlađenje atoma optičkim frekventnim češljem

master's thesis

• Title (english): Frequency comb laser cooling
• Author: Ana Cipriš
• Mentor: Ticijana Ban (mentor)
• Mentor: Hrvoje Buljan (mentor)
• Committee member: Hrvoje Buljan (predsjednik povjerenstva)
• Committee member: Ticijana Ban (član povjerenstva)
• Committee member: Matko Milin (član povjerenstva)
• Committee member: Ivica Smolić (član povjerenstva)
• Committee member: Damir Veža (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2017-06-28, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U ovom diplomskom radu proučavano je hlađenje atoma 87Rb optičkim frekventnim češljem koji nastaje uslijed visoko stabiliziranog zračenja femtosekundnog lasera. Atomi su se hladili pobuđivanjem 52S1/2 (F = 2) → 52P3/2 (F' = 3) prvog rezonantnog elektronskog prijelaza u atomu 87Rb točno određenom spektralnom linijom frekventnog češlja. Temperatura atoma se određivala korištenjem tehnike vremena proleta. Mjerene su temperature za različite konfiguracije polarizacija suprotno propagirajućih femtosekundnih laserskih zraka, kao i ovisnost temperature o magnetskom polju i vremenu interakcije s femtosekundnim laserom. Opaženo je hlađenje do sub-Dopplerovih temperatura s najnižom izmjerenom temperaturom od 66 μK, što predstavlja, prema našim saznanjima, prvu eksperimentalnu realizaciju sub-Dopplerovih temperatura koristeći optički frekventni češalj. U svrhu usporedbe sa standardnim tehnikama hlađenja utemeljenim na kontinuiranim laserima, mjerenja su se ponovila koristeći kontinuirani laser umjesto frekventnog češlja. Dobiveno slaganje izmjerenih temperatura potvrđuje upotrebu optičkog frekventnog češlja za hlađenje atoma, čime se otvara niz novih mogućnosti kao što je hlađenje atoma s prvim rezonantnim prijelazima u ultraljubičastom/vakuum ultraljubičastom dijelu spektra, području nedostupnom emisiji kontinuiranih lasera.

Abstract (english)

In this thesis, cooling of 87Rb atoms using an optical frequency comb resulting from highly stabilized femtosecond laser radiation was studied. Cooling of atoms was obtained by driving 52S1/2 (F = 2) → 52P3/2 (F' = 3) first resonant electronic transition of 87Rb atom with the single frequency comb line. Temperature of the cold atoms was determined using the time of flight technique. Temperature measurements were performed for various polarization configurations of counter propagating femtosecond laser beams. Temperature dependence of magnetic field and time of interaction with femtosecond laser was also measured. Cooling down to sub-Doppler temperatures was observed, with lowest measured temperature of 66 μK. According to our knowledge, this represents first experimental realization of sub-Doppler temperatures using optical frequency comb. For comparation with standard laser cooling techniques based on continuous-wave lasers, measurements were repeated using continuous-wave laser instead frequency comb. Well agreed results confirmed possibility of frequency comb laser cooling of atoms. That opens up a number of new possibilities in laser cooling, such as laser cooling of atoms with first resonant transitions in ultraviolet/vacuum ultraviolet spectrum range, where continuous-wave radiation is unavailable.

• Keywords: optički frekventni češalj; niz femtosekundnih pulseva; lasersko hlađenje; sila zračenja; magneto-optička stupica; atom rubidija; sub-Dopplerova temperatura
• Keywords (english): optical frequency comb; femtosecond pulse train; laser cooling; radiation force; magneto-optical trap; rubidium atom; sub-Doppler temperature
• Language: croatian
• URN:NBN: urn:nbn:hr:217:401970
• Study programme: Title: Physics; specializations in: Research; Course: Research; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra fizike (magistar/magistra fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-07-07 14:35:17