Thermo Dynamics of Ion Coulomb Crystals

激光冷却离子库仑晶体是模拟多体物理最有前途的平台之一。过去对库仑系统的研究主要集中在热力学平衡的纯谐系统上，而最近的研究重点已经转移到非平衡动力学和非线性、不可积模型的研究上。最近的一个挑战是理解低维量子系统中的热传输，因为凝聚态系统正在进入纳米级体系，但微观参数不能很好地控制，热流等热力学量在实验上无法获得。特别是，非线性可以导致热输运中的各种有趣的效应，例如热整流器，这是无法解析的。这个项目将使用离子库仑晶体作为一个控制良好的试验台来研究量子系统中热力学的开始。我们将研究杂质和拓扑缺陷对低维晶体热输运的影响。在第一步，我们将发展光谱技术来研究振动激发的传输和离子与恒温器的耦合。我们将演示低维线性晶体中傅立叶定律的击穿，并研究耗散和非均匀性的影响。第二步，我们将在库仑晶体中掺杂杂质和拓扑缺陷，并测量空间声子分布。在离子中加入噪声可以观察到噪声辅助的热传递。从长远来看，复杂晶体的热化，接近结构相变和具有强非线性的存在将被光谱分析。将振动模式带入量子态，从导电相到隔离相的相变以及纳米摩擦的研究将变得容易。

Laser-cooled ion Coulomb crystals are representing one of the most promising platforms for the simulation of many-body physics. Whereas past work in Coulomb systems was mainly focused on pure and harmonic systems in thermo-dynamic equilibrium, recent attention has shifted to the study of non-equilibrium dynamics and nonlinear, non-integrable models. A recent challenge is the understanding of heat transport in low-dimensional quantum systems, as condensed matter systems are entering the nanoscale regime, but microscopic parameters cannot be well-controlled and thermodynamic quantities such as heat current are experimentally not accessible. In particular, nonlinearities can lead to a variety of intriguing effects in thermal transport, such as thermal rectifiers, that cannot be analytically accessed. This project will use ion Coulomb crystals as a well-controlled test bed to study the onset of thermodynamics in quantum systems. We will investigate the effect of impurities and topological defects on the heat transport of low-dimensional crystals. In a first step, we will develop spectroscopic techniques to study the transport of vibrational excitations and the coupling of the ions to thermostats. We will demonstrate the breakdown of Fouriers law in low-dimensional linear crystals and study the influence of dissipation and inhomogeneity. In a second step, we will dope the Coulomb crystal with impurities and topological defects and measure the spatial phonon distribution. Adding noise to the ions should allow observing noise-assisted heat transport. In the long term, the thermalization of complex crystals, close to structural phase transitions and with strong nonlinearities present will be spectroscopically analyzed. Bringing the vibrational modes to the quantum regime, phase transitions from conducting to isolating phases and the study of nanofriction will become accessible.