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arXiv 1603.04889quant-phcond-mat.quant-gasphysics.atom-phphysics.optics
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弱量子测量诱导的多模玻色系统的集体动力学

Collective dynamics of multimode bosonic systems induced by weak quantum measurement

Gabriel Mazzucchi, Wojciech Kozlowski, Santiago F. Caballero-Benitez, Igor B. Mekhov

摘要:

与强量子测量的完全投影极限相反,在强量子测量中,演化被锁定在一个小子空间(量子芝诺动力学),甚至完全冻结(量子芝诺效应),弱非投影测量可以有效地与标准幺正动力学竞争,导致非平凡效应。在这里,我们考虑全局弱测量解决集体变量,从而保持量子叠加由于缺乏路径信息。当然,我们专注于超冷原子,但这个想法可以推广到其他多模量子系统,包括各种量子发射器,光机阵列和具有多路干涉仪(光子电路)的纯光子系统。我们表明,光散射超冷玻色子在光晶格可以用来定义宏观占据的空间模式,表现出长程相干动力学。即使测量强度保持不变,量子测量反作用也会准周期性地作用于原子系综,引起所有原子的集体振荡动力学。我们引入了一个有效的模型的空间模式的演变,并提出了一个解析解表明,量子跳跃驱动系统远离其稳定点。我们确认我们的发现描述的随机微分方程的原子观测量。

英文摘要:

In contrast to the fully projective limit of strong quantum measurement, where the evolution is locked to a small subspace (quantum Zeno dynamics), or even frozen completely (quantum Zeno effect), the weak non-projective measurement can effectively compete with standard unitary dynamics leading to nontrivial effects. Here we consider global weak measurement addressing collective variables, thus preserving quantum superpositions due to the lack of which path information. While for certainty we focus on ultracold atoms, the idea can be generalized to other multimode quantum systems, including various quantum emitters, optomechanical arrays, and purely photonic systems with multiple-path interferometers (photonic circuits). We show that light scattering from ultracold bosons in optical lattices can be used for defining macroscopically occupied spatial modes that exhibit long-range coherent dynamics. Even if the measurement strength remains constant, the quantum measurement backaction acts on the atomic ensemble quasi-periodically and induces collective oscillatory dynamics of all the atoms. We introduce an effective model for the evolution of the spatial modes and present an analytic solution showing that the quantum jumps drive the system away from its stable point. We confirm our finding describing the atomic observables in terms of stochastic differential equations.

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