Scazza F, Valtolina G, Massignan P, Recati A, Amico A, Burchianti A, Fort C, Inguscio M, Zaccanti M, Roati G
Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy.
LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy.
Phys Rev Lett. 2017 Feb 24;118(8):083602. doi: 10.1103/PhysRevLett.118.083602. Epub 2017 Feb 21.
We employ radio-frequency spectroscopy to investigate a polarized spin mixture of ultracold ^{6}Li atoms close to a broad Feshbach scattering resonance. Focusing on the regime of strong repulsive interactions, we observe well-defined coherent quasiparticles even for unitarity-limited interactions. We characterize the many-body system by extracting the key properties of repulsive Fermi polarons: the energy E_{+}, the effective mass m^{}, the residue Z, and the decay rate Γ. Above a critical interaction, E_{+} is found to exceed the Fermi energy of the bath, while m^{} diverges and even turns negative, thereby indicating that the repulsive Fermi liquid state becomes energetically and thermodynamically unstable.
我们利用射频光谱学来研究接近宽费什巴赫散射共振的超冷(^{6}Li)原子的极化自旋混合物。聚焦于强排斥相互作用区域，即使对于幺正极限相互作用，我们也观察到了明确的相干准粒子。我们通过提取排斥费米极化子的关键性质来表征多体系统：能量(E_{+})、有效质量(m^{})、留数(Z)和衰变率(\Gamma)。在临界相互作用之上，发现(E_{+})超过了热库的费米能量，而(m^{})发散甚至变为负值，从而表明排斥费米液态在能量和热力学上变得不稳定。
