非平衡环境是量子系统应用中最常见的耗散因素之一。系统研究了两耦合量子比特在平衡和非平衡环境下的动力学演化和稳态解。结果表明: 在平衡热库中, 增强耦合强度、增大能量失谐以及适当提高热库温度都有-515.5cm-5 利于纠缠的增强; 而在非平衡热库中, 平均温度低 (高) 时温度梯度会增强 (抑制) 纠缠。另外, 还研究了热流与能量失谐、耦合强度以及热库温度的关系, 发现对于分别处于两个独立热库和两个共同热库中的两量子比特, 相关参数对其演化和热流的影响是不同的。选择适当的耦合强度、能量失谐和温度梯度, 可以使两热库之间存在稳定热流, 从而获得系统的稳态纠缠。

We show how to optimally protect quantum states and freeze coherence under incoherent channels using a quantum weak measurement and quantum measurement reversal. In particular, we present explicit formulas for the conditions for freezing quantum coherence in a given quantum state.

研究了2对非相互作用、空间分离的原子在双模腔场作用下的三体和两体纠缠动力学行为。 对非简并双光子Tavis-Cummings模型进行了研究,通过数值计算分析了纠缠初始状态、原子与腔场以及 光纤模与腔场的耦合强度对纠缠的影响。结果表明:纠缠初始状态对原子间的纠缠有显著影响;较大的场 和光纤模的耦合强度可以实现原子与原子间最大纠缠的转移；较大的原子与腔场耦合强度有助于两原子与腔场构成三体纠缠。

利用数值分析的方法，研究了两运动原子依次通过微腔时两原子的量子关联，讨论了两原子的初始态，腔场光子数及原子的运动对纠缠和量子失协的影响以及纠缠与量子失协的比较。结果表明：初始态可以改变纠缠和量子失谐的演化; 腔场光子数的增加,可以使纠缠和量子失谐由周期性变化到非周期性变化，光子数不为零时，纠缠出现猝死现象，量子失谐保持非零;原子的运动可以使纠缠和量子失谐由非周期性演化变为周期性演化，使周期变短，并且发现原子运动的场模结构参数的增大可以提高纠缠和量子失谐的大小。在某些情况下，纠缠和量子失谐的演化规律具有一致性。

In this letter, we analyze the effects of light intensity on reflective ghost imaging with thermal source. We find that the brightness of reflective ghost image can be changed by modulating the light intensity of the source and the splitting ratio of the beam splitter. The signal-to-noise ratio will be improved by increasing the light intensity of the source. More important, we can obtain the reflective ghost image with high image quality by adopting a low light intensity signal beam and a high light intensity reference beam, which is better than the classical optical imaging, because it can reduce the effects of light on the object.

利用弱测量技术研究两量子比特的量子关联动力学演化和转移。有纠缠突然死亡现象产生的非最大纠缠初态经前选择测量操作后，在演化过程中不但能够提高量子关联强度，而且能够缩短甚至消除量子比特纠缠的突然死亡区域；而对于演化中无纠缠突然死亡的非最大纠缠初态，弱测量操作则会降低量子比特间关联强度。对初始处于最大纠缠态的粒子，弱测量操作不能增强粒子间的纠缠但可以优化量子关联中的量子失谐。弱测量在实现量子关联转移时的破坏极小，能够延迟纠缠的衰减，并可使量子纠缠的转移时间提前。另外腔场与量子比特间的耦合强度与系统耗散率的关系决定纠缠原子在腔中动力学演化，表现为马尔可夫和非马尔可夫过程。

研究了由光纤模连接的两个Tavis-Cummings模型中纠缠演化和纠缠转移的特性。结果表明，初始两原子间的纠缠可转移为另两原子间的纠缠，在纠缠转移过程中，光纤模起到中间传递的作用。纠缠的转移与初始两原子间的纠缠、原子与腔场的耦合强度以及光纤模与腔场的耦合强度、原子与腔场的失谐量和腔场耗散有关。初始纠缠决定了另两原子间纠缠产生的大小；在原子与腔场的耦合强度一定的条件下，随着光纤模与腔场耦合强度的增强，纠缠转移的时间缩短，且产生的纠缠值增加；腔场耗散对纠缠演化的衰减影响是显著的，而失谐量的增加可以有效地抑制这一现象。在整个纠缠转移过程中，系统中其他任两子体系间的纠缠起到了桥梁的作用，实现了两量子纠缠态的远程传递和制备。

We analyze entanglement dynamics and transfer in a system composed of two initially correlated two-level atoms, in which each atom is coupled with another atom interacting with its own reservoir. Considering atomic dipole-dipole interactions, the results show that dipole-dipole interactions restrain the entanglement birth of the reservoirs, and a parametric region of dipole-dipole interaction strength exists in which the maximal entanglement of two initially uncorrelated atoms is reduced. The transfer of entanglement shows obvious different behaviors in two initial Bell-like states.

In this letter, we use quantum description and the Gaussian state to study reflective ghost imaging with two classical sources, and to provide their expressions. We find that the reflective ghost imaging of a rough-surfaced object, using Gaussian-state phase-insensitive or classically correlated phase-sensitive light, can be expressed in terms of the phase-insensitive or phase-sensitive cross-correlations between the two detected fields, including a background term. Moreover, reflective ghost imaging with two classical Gaussian-state lights is shown to have similar features as spatial resolution and field of view.