Laser cooling, friction, and diffusion in a three-level cascade system

Laser cooling, friction, and diffusion in a three-level cascade system

A model is presented to calculate optical forces, friction, and diffusion for three-level atoms in a ladder configuration. This model is then applied to the 2S1-2 P2-3 D3 cascade in metastable helium. It is demonstrated that metastable helium atoms can be decelerated within a much shorter distance using cascade excitation by overlapping traveling waves. The equilibrium temperature representing ...

Bichromatic laser cooling in a three-level system.

Two-photon and electromagnetically-induced-transparency-assisted Doppler cooling in a three-level cascade system

Laser cooling is theoretically investigated in a cascade three-level scheme, where the excited state of a laser-driven transition is coupled by a second laser to a top, more stable level, as for alkaline-earth-metal atoms. The second laser action modifies the atomic scattering cross section and produces temperatures lower than those reached by Doppler cooling on the lower transition. When multi...

proficiency level and factors fostering reticence in efl learners

according to cheng (1999), in recent esl/efl literature, asian (especially east asian) learners of english as a foreign/second language have been arguably reported as reticent and passive learners. the most common allegations are that these students are reluctant to participate in classroom discourse; they are unwilling to give responses; they do not ask questions; and they are passive and over...

a comparative study of the theme of "marriage" in three victorian novelists: charles dickens, george eliot and thomas hardy

این تحقیق کوشیده است با انتخاب پنج رمان از میان آثار برگزیده، «چارلز دیکنز»، «جورج الیوت» و «توماس هاردی » و با رویکردی تطبیقی به بررسی درونمایه ی «ازدواج» در آثار این سه رمان نویس بزرگ دوره ی ویکتوریا بپردازد. فرضیه ی اولیه ی تحقیق این بوده است که چارلز دیکنز (1870- 1812) با زبانی شوخ و گزنده، جورج الیوت(1880- 1819) با نگاهی آموزشی–اندرزگونه و توماس هاردی(1928- 1840) با رویکردی تلخ وانتقادی به...