标题： 宏观量子空间叠加中的磁噪声 显示英文标题

标题： Magnetic noise in macroscopic quantum spatial superposition

摘要： 在本文中，我们将展示磁场中的随机波动如何随机地使物质波干涉仪的路径发生抖动，从而导致量子叠加态的退相干。 为了用纳米粒子创建一个大的空间叠加态，我们设想在纳米粒子中嵌入一个自旋作为缺陷，并像斯特恩-格拉赫实验一样施加不均匀的磁场来创建宏观的量子叠加态。 这种物质波干涉仪是物理学许多新基础进展的核心；特别是，相邻的物质波干涉仪可以利用纠缠特性来检验标准模型之外的物理规律，检验等效原理，提高量子传感器的性能，并在实验室中检验时空的量子性质。 特别是，我们将使用白噪声和闪烁噪声来研究退相干，并在考虑适合芯片上超导线的环境温度的情况下约束参数。 我们将证明，为了获得纳米级分离的微小空间叠加态，$\Delta x \sim {\cal O} (10^{-9})$m 并最小化退相干，$\Gamma\leq {\cal O}(\frac{\omega_0}{2\pi})$，其中$\Gamma$是退相干，$\omega_0$是振荡器的频率，我们需要电流波动为$\delta I/I\leq {\cal O}(10^{-8})$，这在超导线结构中是有可能实现的。 对于如此微小的波动，我们证明了由于位置和动量不匹配而在物质波干涉仪中出现的“哈姆雷特问题”不会导致对比度的损失。 显示英文摘要

摘要： In this paper, we will show how random fluctuations in the magnetic field will jitter the paths of a matter-wave interferometer randomly, hence, decohere the quantum superposition. To create a large spatial superposition with nanoparticles, we envisage embedding a spin in a nanoparticle as a defect and applying an inhomogeneous magnetic field as in a Stern-Gerlach type experiment to create a macroscopic quantum superposition. Such matter-wave interferometers are the cornerstone for many new fundamental advancements in physics; particularly, adjacent matter-wave interferometers can use entanglement features to test physics beyond the Standard Model, test the equivalence principle, improve quantum sensors, and test the quantum nature of spacetime in a lab. In particular, we will use white and flicker noise to study the decoherence and constrain the parameters keeping in mind ambient temperatures suitable for superconducting wires embedded on a chip. We will show that to obtain a tiny spatial superposition of a nanometer separation, $\Delta x \sim {\cal O} (10^{-9})$m and to minimize decoherence, $\Gamma\leq {\cal O}(\frac{\omega_0}{2\pi})$, where $\Gamma$ is the decoherence and $\omega_0$ is the frequency of the oscillator, we will need current fluctuations to be $\delta I/I\leq {\cal O}(10^{-8})$, which is not impossible to obtain in superconducting wire arrangements. For such tiny fluctuations, we demonstrate that the Humpty-Dumpty problem in a matter-wave interferometer arising from a mismatch in position and momentum does not cause a loss in contrast.