量子光学学报
量子光學學報
양자광학학보
ACTA SINICA QUANTUM OPTICA
2008年
3期
246-252
,共7页
幅值损耗腔%∧型三能级原子%条件熵纠缠度%密度矩阵
幅值損耗腔%∧型三能級原子%條件熵糾纏度%密度矩陣
폭치손모강%∧형삼능급원자%조건적규전도%밀도구진
Amplitude dissipative cavity%A-type atoms%Entanglement degree of quantum conditional entropy%Density matrix
利用超算符方法求解幅值损耗腔中两个∧型三能级原子与相干光场相互作用系统的主方程,并利用量子条件熵研究了两个初始为|Ψa(0)>和|Φa(0)>纠缠态的原子与光场作用过程中原子的纠缠演化特性.讨论了不同初始原子纠缠度,不同耗散系数以及不同平均光子数对两原子纠缠度的影响.结果表明:①当原子初始处于|Ψa(0)>类纠缠态时,其纠缠度随光场强度以及腔场衰减系数演化.当腔不存在耗散时,纠缠度呈周期性振荡;当腔存在耗散时,纠缠度呈衰减振荡并趋于稳定值;且光强越弱,其稳定值越大;衰减系数越大纠缠达到稳定值所需时间越短.②原子初始处于|Φa(0)>类纠缠态时,其纠缠度只与原子初始纠缠度有关,不随其他因素变化.
利用超算符方法求解幅值損耗腔中兩箇∧型三能級原子與相榦光場相互作用繫統的主方程,併利用量子條件熵研究瞭兩箇初始為|Ψa(0)>和|Φa(0)>糾纏態的原子與光場作用過程中原子的糾纏縯化特性.討論瞭不同初始原子糾纏度,不同耗散繫數以及不同平均光子數對兩原子糾纏度的影響.結果錶明:①噹原子初始處于|Ψa(0)>類糾纏態時,其糾纏度隨光場彊度以及腔場衰減繫數縯化.噹腔不存在耗散時,糾纏度呈週期性振盪;噹腔存在耗散時,糾纏度呈衰減振盪併趨于穩定值;且光彊越弱,其穩定值越大;衰減繫數越大糾纏達到穩定值所需時間越短.②原子初始處于|Φa(0)>類糾纏態時,其糾纏度隻與原子初始糾纏度有關,不隨其他因素變化.
이용초산부방법구해폭치손모강중량개∧형삼능급원자여상간광장상호작용계통적주방정,병이용양자조건적연구료량개초시위|Ψa(0)>화|Φa(0)>규전태적원자여광장작용과정중원자적규전연화특성.토론료불동초시원자규전도,불동모산계수이급불동평균광자수대량원자규전도적영향.결과표명:①당원자초시처우|Ψa(0)>류규전태시,기규전도수광장강도이급강장쇠감계수연화.당강불존재모산시,규전도정주기성진탕;당강존재모산시,규전도정쇠감진탕병추우은정치;차광강월약,기은정치월대;쇠감계수월대규전체도은정치소수시간월단.②원자초시처우|Φa(0)>류규전태시,기규전도지여원자초시규전도유관,불수기타인소변화.
The entanglement between two A-type three-level atoms interacting with coherent field in a dissipative cavity is investigated by means of the entanglement degree of quantum conditional entropy.A solution of the master equation is obtained by super operator method.The authors discuss the entanglement between the two atoms based on two kinds of different initial states(|Ψa(0)>,|Φa(0)>)and analyze the influence of decay coefficient of the cavity and mean photon number of the field on entanglement degree.In conclusion,when the atoms are initially in entangled state |Ψa(0)>,the evolution of the entanglement degree depends on decay coefficient of the cavity and intensity of the field.If there is absence of dissipation,the entanglement degree evolves periodically;otherwise,the entanglement degree decays sharply and approaches a stable value.The weaker the intensity of the field is,the greater the stable value becomes.The greater the decay coefficient is,the faster it reaches the stable value.But for the other initial entangled state |Φa(O)>,the entanglement between the two atoms doesnt evolve with the time.It implies that the entangled state|Φa(0)>can be preserved in such a dissipative system.