Efficient fluorescence detection of a single neutral atom with low background in a microscopic optical dipole trap  

作　　者：GUO YanQiang LI Gang ZHANG YanFeng ZHANG PengFei WANG JunMin ZHANG TianCai 

机构地区：[1]State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2012年第9期1523-1528,共6页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the State Basic Key Research Program of China (Grant No. 2012CB921601);China National Funds for Distinguished Young Scientists (Grant No. 11125418);the National Natural Science Foundation of China (Grant Nos. 10974125,61121064 and60978017)

摘　　要：A single cesium atom is trapped in a far-off-resonance optical dipole trap （FORT） from the magneto-optical trap （MOT） and directly imaged by using a charge-coupled device （CCD） camera. The binary single-atom steps and photon anti-bunching are observed by a photon-counting-based HBT system using fluorescence light. The average atom dwelling time in the FORT is about 9 s. To reduce the background noise in the detection procedure we employ a weak probe laser tuned to the D1 line to il- lurninate the single atom from the direction perpendicular to the large-numerical-aperture collimation system. The second or- der degree of coherence g（2）（r）=0.12_＋0.02 is obtained directly from the fluorescence light of the single atom without deducting the background. The background light has been suppressed to 10 counts per 50 ms, which is much lower compared with the reported results. The measured g（2）（r） is in good agreement with theoretical analysis. The system provides a simple and effi- cient method to manipulate and measure single neutral atoms, and opens a way to create an efficient controlled single-photon source.A single cesium atom is trapped in a far-off-resonance optical dipole trap(FORT) from the magneto-optical trap(MOT) and directly imaged by using a charge-coupled device(CCD) camera.The binary single-atom steps and photon anti-bunching are observed by a photon-counting-based HBT system using fluorescence light.The average atom dwelling time in the FORT is about 9 s.To reduce the background noise in the detection procedure we employ a weak probe laser tuned to the D 1 line to illuminate the single atom from the direction perpendicular to the large-numerical-aperture collimation system.The second order degree of coherence g(2)()=0.12±0.02 is obtained directly from the fluorescence light of the single atom without deducting the background.The background light has been suppressed to 10 counts per 50 ms,which is much lower compared with the reported results.The measured g(2)() is in good agreement with theoretical analysis.The system provides a simple and efficient method to manipulate and measure single neutral atoms,and opens a way to create an efficient controlled single-photon source.

关 键 词：magneto-optical trap （MOT） far-off-resonance optical dipole trap （FORT） single atom collisional blockade second- order correlation function 

分 类 号：O562[理学—原子与分子物理] Q503[理学—物理]