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Doctoral Thesis
DOI
10.11606/T.76.2010.tde-11052010-154900
Document
Author
Full name
Stella Torres Muller
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2010
Supervisor
Committee
Bagnato, Vanderlei Salvador (President)
Acioli, Lucio Hora
Cesar, Claudio Lenz
Cruz, Flávio Caldas da
Magalhães, Daniel Varela
Title in Portuguese
Padrão de frequência compacto
Keywords in Portuguese
Césio
Espectroscopia Ramsey
Metrologia
Padrão de frequência atômico
Relógio atômico
Abstract in Portuguese
Apresentamos os aspectos mais relevantes para a construção e caracterização de um padrão primário de tempo e frequência compacto. Nesse sistema a amostra de átomos de referência é preparada a partir de uma armadilha magneto-óptica. Após a obtenção de uma amostra significativa de átomos os feixes laser são desligados e, durante a expansão livre, a nuvem atômica é submetida a uma sequência de pulsos de micro-ondas que caracterizam o método de Ramsey. Os pulsos de micro-ondas são aplicados em uma cavidade de micro-ondas, esculpida dentro da câmara de vácuo. Todo o ciclo de funcionamento é implementado dentro dessa cavidade e por esse motivo o padrão é considerado compacto. Quando os átomos são interrogados com pulsos de τ = 1 ms separados por Τ = 8 ms obtemos uma largura a meia altura da franja central de 52 Hz e uma estabilidade a curto prazo de 10-13. Alguns causadores de deslocamentos de frequência foram avaliados.
Title in English
Compact frequency standard
Keywords in English
Atomic clock
Atomic frequency standard
Cesium
Metrology
Ramsey spectroscopy
Abstract in English
We present some relevant aspects for the construction and characterization of a compact primary frequency standard. In this system, the atomic ensemble is prepared with a magnetooptical trap. Once a significant number of cold atoms is obtained, the laser beams are turned off and, during the free expansion, the cloud is submitted to a sequence of two microwave pulses, characterizing the well-known Ramsey method. The microwave pulses are applied in a microwave cavity that was sculpted inside the vacuum chamber. All the working cycle takes place into this cavity. When the atoms are interrogated by two pulses of τ = 1 ms separated by Τ = 8 ms, the linewidth of the central fringe is 52 Hz and a short-term stability 10-13 is observed. Some frequency shifts were evaluated.
 
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Publishing Date
2010-05-13
 
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