纠缠相干光场对量子态最大演化速率的操控

考虑双模纠缠相干光场,将其中一束光场注入腔中与一个二能级原子发生共振相互作用,根据腔量子电动力学理论推导出原子系统的演化态.针对原子系统初始状态到目标演化态的动力学过程,利用量子速率极限时间概念来表征原子系统量子态的最大演化速率.通过调节双模纠缠相干光场的相干参数来操控原子系统量子态动力学过程中所能达到的最大演化速率.结果发现:与原子发生相互作用光场的相干参数在一定条件下可以对系统量子态的最大演化速率产生明显的影响;并且当该光场参数不能很好地来操控量子态的最大演化速率时,双模纠缠相干光场间的量子关联可以实现未参加相互作用光场参数对原子系统量子态最大演化速率的远程调控.     

Coherent-driving-assisted quantum speedup in Markovian channels

As is well known,the quantum evolution speed of quantum state can never be accelerated in the Markovian regime without any operators on the system.The Hamiltonian corrections induced by the action of coherent driving forces are often used to fight dissipative and decoherence mechanisms in experiments.For this reason,considering three noisy channels(the phase-flip channel,the amplitude damping channel and the depolarizing channel),we propose a scheme of speedup evolution of an open system by controlling an external unitary coherent driving operator on the system.It is shown that,in the presence of the coherent driving,no-speedup evolution can be transformed into quantum speedup evolution in the Markovian dynamics process.Additionally,under the fixed coherent driving strength in the above three noisy channels,the best way to achieve the most degree of quantum speedup for the system has been acquired by rotating the system with appropriate driving direction angles,respectively.Finally,we conclude that the reason for this acceleration is not the nonMarkovian dynamical behavior of the system but due to the oscillation of geometric distance between the initial state and the target final state.