Highly Sensitive Detection Of Rydberg Atoms In Cold Atoms With Fluorescence Loss Method

Ultra-cold atoms have played more important role in physics research due to its unique physical properties.After more than 30 years of development,ultra-cold atoms have been become an ideal platform with diverse application in fundamental physics researches such as the properties of BEC,and also can be used in practical devices such as atomic clock which is applied for precise measurement of time.For Rydberg atoms,the unique properties of it lead to variety of interesting researches.For example,the generation and evolution of plasma can be performed with Rydberg atoms due to the weak bounding of the outermost electrons.It can be used in microwave measurement because of it can be easily manipulated by field.Besides,its longer lifetime can carry out measurement studies of spectral characteristics.The strong long-range interaction of Rydberg atoms is exploited for quantum information application.Combining the ultra-cold atoms and Rydberg atoms sheds a light on new path for quantum researches.We produced ultra-cold Rydberg atoms in a magneto-optical trap and detected them with fluorescence loss spectrum in this essay.By adding a frequency modulation to the cooling lasers which the signal to noise ratio of the spectrum have been optimized.This modulated fluorescence loss spectrum technique provides a simpler,versatile,and non-destructive method for the detection of Rydberg atoms.The results of the experiment are in good agreement with the theory.This essay is mainly divided into four parts,and the specific introduction is as follows:The introduction of the first chapter mainly introduces the properties and development applications of cold atoms and Rydberg atoms,the research background of this work.It briefly introduced the historical development of ultra-cold atoms and Rydberg atoms,and their related characteristics.And next several detection techniques of Rydberg atoms and applications of those methods are introduced.Chapter 2 is describing the principle of the experiment including the interaction between laser and atoms,the mechanism of cascade three levels of Rydberg excitation,and the fundamental behavior of the magneto-optical trap.Chapter 3 gives a description of the experimental setup.The constructions of the magneto-optical trap and the fluorescence loss spectrum detection setup,such as vacuum system,lasers and optical system,magnetic fields and computer control system.Chapter 4 describes the frequency modulated process of the experiment and experimental results,and the experimental results agree with the theoretical calculations.In the experiment we measured the characteristics of the trapped atoms such as the number,temperature and density,and described the process of the frequency modulation on the cooling laser.The sweep speed and power of the couple laser were optimized by measuring the influence after changing the modulation frequency and modulation amplitude.The simulated results from two aspects have good agreements with the experiment.The innovations of this work are as follows:In this work we provided a high sensitive detection method to detect the Rydberg atoms by fluorescence loss spectrum of intermediate state.The signal to noise ratio has been significantly improved by frequency modulation method.We analyzed the results considering the effects of the modulation on both the trapping process of intermediate states and Rydberg atoms excitation.The Rydberg atoms detection methods are mainly divide into destructive and non-destructive detection,and to detect it a kind of the non-destructive method was proposed in this paper,as well as this technology setup is simpler and versatile.