Ferrier Meydi, Arakawa Tomonori, Hata Tokuro, Fujiwara Ryo, Delagrange Raphaëlle, Deblock Richard, Teratani Yoshimichi, Sakano Rui, Oguri Akira, Kobayashi Kensuke
Department of Physics, Graduate School of Science, Osaka University, 560-0043 Osaka, Japan.
Laboratoire de Physique des Solides, CNRS, Univ. Paris-sud, Université Paris Saclay, 91405 Orsay Cedex, France.
Phys Rev Lett. 2017 May 12;118(19):196803. doi: 10.1103/PhysRevLett.118.196803. Epub 2017 May 11.
Universal properties of entangled many-body states are controlled by their symmetry and quantum fluctuations. By the magnetic-field tuning of the spin-orbital degeneracy in a Kondo-correlated quantum dot, we have modified quantum fluctuations to directly measure their influence on the many-body properties along the crossover from SU(4) to SU(2) symmetry of the ground state. High-sensitive current noise measurements combined with the nonequilibrium Fermi liquid theory clarify that the Kondo resonance and electron correlations are enhanced as the fluctuations, measured by the Wilson ratio, increase along the symmetry crossover. Our achievement demonstrates that nonlinear noise constitutes a measure of quantum fluctuations that can be used to tackle quantum phase transitions.
纠缠多体状态的普遍性质由其对称性和量子涨落控制。通过对近藤关联量子点中自旋 - 轨道简并性进行磁场调谐，我们改变了量子涨落，以直接测量它们在基态从SU(4)到SU(2)对称性转变过程中对多体性质的影响。结合非平衡费米液体理论的高灵敏度电流噪声测量结果表明，随着由威尔逊比率测量的涨落在对称性转变过程中增加，近藤共振和电子关联增强。我们的成果表明，非线性噪声构成了一种可用于处理量子相变的量子涨落度量。
