量子关联的绝热操控和退相干动力学

Adiabatic manipulation and decoherence dynamics of quantum correlations

在电磁诱导光透明机制下,通过绝热操控驱动场,运用Quantum Discord (QD)度量理论,研究了系综内两原子之间量子关联的生成.理论表明量子关联依赖于不同的激发模式、光子数n、系综内的原子个数N以及驱动场频率.在满激发和半激发模式下,通过调节驱动场系综能够生成最好的量子关联.考虑退相干后,我们研究了量子关联在3种退相干渠道下的动力学,发现量子关联始终不会出现突然死亡的现象.进一步比较了不同激发模式生成的量子关联在3种退相干渠道下的存活能力.通过满激发模式小混合角生成的量子关联,在振幅阻尼渠道下有较强的存活能力;而对于大混合角生成的量子关联,则在相位阻尼渠道下有较强的存活能力.通过半激发模式生成的量子关联,对于任意的混合角,在振幅阻尼渠道有较强的存活能力,但是,当混合角增加到临界值时,量子关联在相位阻尼渠道和退极化渠道下的存活能力将出现翻转,这个角度临界值随着原子个数的增加向π/2靠近.通过低激发模式生成的量子关联,在振幅阻尼渠道下有较强的存活能力,在相位阻尼渠道下次之,而在退极化渠道下最弱.

By adiabatically manipulating the Rabi frequency of the drive field,the quantum discord(QD)has been used to analyze the quantum correlation for two atoms of the ensemble under the electromagnetically induced transparency(EIT)mechanism.It is shown that,the quantum correlation of two atoms depends on the Rabi frequency of the drive field,the excitation mode,the photon number and the atom number of the ensemble.If more than half of atoms were excited,the ensemble can generate the maximum quantum correlation.Furthermore,we investigate the behavior of the quantum correlation under three decoherence channels respectively.It is found that the sudden death of the quantum correlation do not exist in any decoherence channel.Generated via the full excitation mode with a small mixed angle,the quantum correlation has a strong survival ability under the amplitude damping channel,but for a larger mixed angle,the survival ability is stronger under phase damping channel.The quantum correlation generated via the half excitation mode displays a strong survive ability for arbitrary mixed angle under the amplitude damping channel.By manipulating the Rabi frequency in this excitation mode,for an appropriate mixed angel,survivability of quantum correlation reverses under the phase damping channel and the depolarizing channel.But when the mixed angle reaches the critical value towardsπ/2 with the number of atoms increasing.For the low excitation mode with any mixed angle,the quantum correlation survives more easily under the amplitude damping channel,conversely,it survives more difficultly under the depolarizing channel.