Quantum Anomaly and 2D-3D Crossover in Strongly Interacting Fermi Gases.
Quantum Anomaly and 2D-3D Crossover in Strongly Interacting Fermi Gases.
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DOI：
10.1103/physrevlett.121.120402
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发表时间：
2018-04
影响因子：
8.6
通讯作者：
T. Peppler;P. Dyke;M. Zamorano;I. Herrera;S. Hoinka;C. Vale
中科院分区：
文献类型：
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作者：
T. Peppler;P. Dyke;M. Zamorano;I. Herrera;S. Hoinka;C. Vale
我们通过二维到三维的交叉实验研究了简谐囚禁费米气体中的集体振荡。具体地说，我们测量了具有可调相互作用的高度扁平气体中的径向单极振荡或呼吸模式的频率。呼吸模式频率由绝热压缩系数确定，并探讨了热力学状态方程。在2D中，原子通过δ势相互作用的动力学标度对称性预测呼吸模式恰好发生在谐和限制频率的两倍。然而，重整化量子处理引入了一个新的长度标度，它打破了经典标度不变性，导致了所谓的量子反常。我们在2D区域深处的测量结果高于对一系列相互作用强度的标度不变预测，为量子反常提供了证据，并标志着原子相互作用的基本δ势模型的崩溃。通过改变原子数目，我们可以调节化学势，并看到呼吸模频率在2D到3D热力学极限之间平滑地演变。
We present an experimental investigation of collective oscillations in harmonically trapped Fermi gases through the crossover from two to three dimensions. Specifically, we measure the frequency of the radial monopole oscillation or breathing mode in highly oblate gases with tunable interactions. The breathing mode frequency is set by the adiabatic compressibility and probes the thermodynamic equation of state. In 2D, a dynamical scaling symmetry for atoms interacting via a δ potential predicts the breathing mode to occur at exactly twice the harmonic confinement frequency. However, a renormalized quantum treatment introduces a new length scale which breaks this classical scale invariance resulting in a so-called quantum anomaly. Our measurements deep in the 2D regime lie above the scale-invariant prediction for a range of interaction strengths providing evidence for the quantum anomaly and signifying the breakdown of an elementary δ-potential model of atomic interactions. By varying the atom number we can tune the chemical potential and see the breathing mode frequency evolve smoothly between the 2D to 3D thermodynamic limits.