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arXiv 1111.6840quant-ph
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连续时间、非马尔可夫演化和反馈中的量子测量

Quantum measurements in continuous time, non Markovian evolutions and feedback

Alberto Barchielli, Matteo Gregoratti

摘要:

在这篇文章中,我们重新考虑了一个版本的量子轨道理论的基础上随机薛定谔方程的随机系数,这是在90年代的数学介绍,我们发展它,以描述非马尔可夫演化的量子系统连续测量和控制感谢基于测量的反馈。实际上,反馈回路的真实描述必须包括延迟,因此需要非马尔可夫理论。该理论允许把非马尔可夫演化和测量在连续时间与现代公理化的量子力学的制定协议。为了说明这种理论的可能性,我们将其应用到一个由激光激发的二能级原子。我们还通过激励激光引入闭环控制,目的是增强发射光的“压缩”或其他典型的量子特性。注意,这里我们改变了关于控制理论的通常应用的观点。在我们的模型中,“系统”是二能级原子,但我们不想控制它的状态,使原子达到最终的目标状态。我们的目标是控制“曼德尔$Q$参数”和发射光的光谱;特别是光谱不是一个单一的时间属性,但涉及到一个很长的时间间隔(观察输出的自相关函数的傅立叶变换是必要的)。

英文摘要:

In this article we reconsider a version of quantum trajectory theory based on the stochastic Schrödinger equation with stochastic coefficients, which was mathematically introduced in the '90s, and we develop it in order to describe the non Markovian evolution of a quantum system continuously measured and controlled thanks to a measurement based feedback. Indeed, realistic descriptions of a feedback loop have to include delay and thus need a non Markovian theory. The theory allows to put together non Markovian evolutions and measurements in continuous time in agreement with the modern axiomatic formulation of quantum mechanics. To illustrate the possibilities of such a theory, we apply it to a two-level atom stimulated by a laser. We introduce closed loop control too, via the stimulating laser, with the aim to enhance the "squeezing" of the emitted light, or other typical quantum properties. Note that here we change the point of view with respect to the usual applications of control theory. In our model the "system" is the two-level atom, but we do not want to control its state, to bring the atom to a final target state. Our aim is to control the "Mandel $Q$-parameter" and the spectrum of the emitted light; in particular the spectrum is not a property at a single time, but involves a long interval of times (a Fourier transform of the autocorrelation function of the observed output is needed).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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