Title: Quantum Fluctuations along Symmetry Crossover in Kondo-correlated Quantum Dot,
Abstract: Universal properties of entangled many-body states are controlled by their
symmetry and quantum fluctuations. By 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 non-equilibrium
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 non-linear noise
constitutes a measure of quantum fluctuations that can be used to tackle
quantum phase transitions.