Bose polarons near quantum criticality
Bose polarons near quantum criticality
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DOI：
10.1126/science.aax5850
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发表时间：
2019-04
期刊：
影响因子：
56.9
通讯作者：
Zoe Z. Yan;Yiqi Ni;C. Robens;M. Zwierlein
中科院分区：
文献类型：
--
作者：
Zoe Z. Yan;Yiqi Ni;C. Robens;M. Zwierlein
在固体中，移动的电子可以使它们的环境--离子晶格--充满杂质，产生被称为极化子的准粒子。在量子气体中，类似的现象可以通过将杂质原子放入不同种类的原子组成的密度更大的气体中来研究。Yan等人研究了玻色极化子的行为，这种准粒子由钾-40的杂质原子浸入钠-23原子的玻色气体中组成。在量子临界点附近，极化子的寿命遵循所谓的普朗克尺度。研究了由钾-40的杂质原子浸入钠-23原子气体中组成的准粒子。准粒子在相互作用物质中的出现是现代物理学的基石之一。然而，在量子临界点附近，准粒子的存在受到质疑。在这里，我们通过将原子杂质浸入具有近共振相互作用的玻色-爱因斯坦凝聚体（BEC）中来创建量子临界附近的玻色极化子。使用射频光谱，我们探测的能量，光谱宽度，和短程相关的杂质作为温度的函数。在远低于超流体临界温度的情况下，杂质形成了定义明确的准粒子。它们的逆寿命，由它们的光谱宽度给出，在所谓的普朗克尺度下随温度线性增加，与量子临界行为一致。在接近BEC临界温度时，光谱宽度超过了杂质的结合能，表明准粒子图像的崩溃。
Immersing the impurities In solids, moving electrons can polarize their environment, the ionic crystal lattice, creating quasi particles known as polarons. An analogous phenomenon can be studied in quantum gases by placing impurity atoms into a much denser gas of atoms of a different species. Yan et al. studied the behavior of Bose polarons, quasiparticles consisting of impurity atoms of potassium-40 immersed in a Bose gas of sodium-23 atoms. In the vicinity of a quantum critical point, the lifetime of the polarons followed the so-called Planckian scale. Science, this issue p. 190 Quasiparticles consisting of impurity atoms of potassium-40 immersed in a gas of sodium-23 atoms are studied. The emergence of quasiparticles in interacting matter represents one of the cornerstones of modern physics. However, in the vicinity of a quantum critical point, the existence of quasiparticles comes under question. Here, we created Bose polarons near quantum criticality by immersing atomic impurities in a Bose-Einstein condensate (BEC) with near-resonant interactions. Using radiofrequency spectroscopy, we probed the energy, spectral width, and short-range correlations of the impurities as a function of temperature. Far below the superfluid critical temperature, the impurities formed well-defined quasiparticles. Their inverse lifetime, given by their spectral width, increased linearly with temperature at the so-called Planckian scale, consistent with quantum critical behavior. Close to the BEC critical temperature, the spectral width exceeded the impurity’s binding energy, signaling a breakdown of the quasiparticle picture.