We present a novel feedback control method for quantum systems. Feedback does not affect the controlled system itself. Instead, it controls the unravelling of the quantum channel of interaction between the system and its environment. This interaction can be represented as a history of events. If their informational content is changed, their back-action on the system is also modified. Feedback action is trigged by the events, thus granting the system the degree of control over its own state. The efficiency of the proposed scheme is demonstrated on the example of two-mode atomic Bose-Einstein condensate, with one of its modes subject to phase-contrast imaging in a Mach–Zehnder interferometer. The histories of photocounts in the output channels of the interferometer are used for feedback. Its capabilities of state engineering are studied for different settings of the feedback loop and different numbers of events in the recorded histories.

我们提出了一种新颖的量子系统反馈控制方法。反馈不会影响受控系统本身。相反，它控制着系统与其环境之间相互作用的量子通道的瓦解。这种交互可以表示为事件的历史。如果他们的信息内容发生改变，他们对系统的反作用也会被修改。反馈动作由事件触发，从而赋予系统对其自身状态的一定程度的控制。该方案的效率在双模原子玻色-爱因斯坦凝聚体的例子中得到了证明，其中一种模式在马赫-曾德尔干涉仪中进行相衬成像。干涉仪输出通道中的光计数历史用于反馈。针对不同的反馈循环设置和记录的历史中不同数量的事件，研究了其状态工程的能力。