二能级和Λ型三能级系统中粒子布居的完全转移

Complete transfer of atomic population in two level states and Λ-three-level states system

采用缀饰态理论和能级交叉技术,分析了二能级和Λ型三能级系统的Stark快速绝热过程(Stark-Chirped Rapid Adiabatic Passage,简称SCRAP).SCRAP过程使用了两束激光脉冲,一束为近共振的泵浦脉冲,把粒子从基态驱动到激发态;另一束为远离共振的强Stark脉冲,它调节两能态之间的玻尔频率,使其与泵浦跃迁频率达到共振,产生两个交叉点.结果表明,适当选择脉冲间的延迟时间,可使泵浦脉冲在一个交叉点周围足够强,在另一个交叉点周围足够弱,粒子从基态转移到激发态的效率可以达到最大值1.

The stark-chirped rapid adiabatic passage （SCRAP） is analyzed, which can give a complete transfer of atomic or molecular population between two bound states in the two level states and ∧ -three-level state, by means of level-crossing technique and dressed states theory. SCRAP uses two laser pulses： a nearly-resonant pump laser pulse drives the population between a ground state and an excited state, and an intense far-off-resonance Stark laser pulse modifies the transition frequency and resonates with the Bohr transition frequency for two level crossings. A population-transfer maximal efficiency approaching unity is provided from the ground state to the excited state, when the delay of the Stark-shifting pulse with respect to the pulse of the coupling-laser frequency is appropriate and guarantees the pump pulse is strong at one of these crossings and is weak at second one.