观察量子相变的出现--一层一层地观察
Observing the emergence of a quantum phase transition -- shell by shell
摘要：
多体物理学所描述的现象，不能只看系统的组成部分来理解。引人注目的表现是对称性破缺、相变和集体激发。几十年来，理解这种集体行为是如何在将单个粒子组装成一个系统时出现的，一直是原子、核和固态物理学的一个愿景。在这里，我们观察到的量子相变从正常的超流相的少体前体。转变的信号是软化的模式与振幅振动的序参量，通常被称为希格斯模式。我们实现了对受限于二维简谐势的超冷费米子的精细控制，并高保真制备了基态的2、6和12个费米子原子的闭壳层构型。然后在我们的介观系统上进行光谱分析，同时将对能量从零调整到大于壳层间距。使用全原子计数统计，我们发现最低的共振相干激发对组成的。这种多体激发的独特的非单调相互作用依赖性以及与数值计算的比较使我们能够将其确定为希格斯模式的前身。我们的原子模拟器开辟了新的途径，系统地解开集体现象的出现和热力学极限粒子粒子。
英文摘要：
Many-body physics describes phenomena which cannot be understood looking at a systems' constituents alone. Striking manifestations are broken symmetry, phase transitions, and collective excitations. Understanding how such collective behaviour emerges when assembling a system from individual particles has been a vision in atomic, nuclear, and solid-state physics for decades. Here, we observe the few-body precursor of a quantum phase transition from a normal to a superfluid phase. The transition is signalled by the softening of the mode associated with amplitude vibrations of the order parameter, commonly referred to as a Higgs mode. We achieve exquisite control over ultracold fermions confined to two-dimensional harmonic potentials and prepare closed-shell configurations of 2, 6 and 12 fermionic atoms in the ground state with high fidelity. Spectroscopy is then performed on our mesoscopic system while tuning the pair energy from zero to being larger than the shell spacing. Using full atom counting statistics, we find the lowest resonance to consist of coherently excited pairs only. The distinct non-monotonic interaction dependence of this many-body excitation as well as comparison with numerical calculations allows us to identify it as the precursor of the Higgs mode. Our atomic simulator opens new pathways to systematically unravel the emergence of collective phenomena and the thermodynamic limit particle by particle.
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。
