Spectral function and fidelity susceptibility in quantum critical phenomena

In this paper, we derive a simple equality that relates the spectral function $I(k,\omega)$ and the fidelity susceptibility $\chi_F$, i.e. $\chi_F=\lim_{\eta\rightarrow 0}\frac{\pi}{\eta} I(0, i\eta)$ with $\eta$ being the half-width of the resonance peak in the spectral function. Since the spectral function can be measured in experiments by the neutron scattering or the angle-resolved photoemission spectroscopy(ARPES) technique, our equality makes the fidelity susceptibility directly measurable in experiments. Physically, our equality reveals also that the resonance peak in the spectral function actually denotes a quantum criticality-like point at which the solid state seemly undergoes a significant change.Comment: 5 pages, 2 figure

Industry Labor Force Quality: An Investigation from the Customer Service Perspective

To investigate the labor force quality deficiency in the Macao casino industry, this study conducted a survey among Macao casino guests on their assessment of customer service. The mean scores of different service features were calculated and compared across casinos operated by different casino companies. Furthermore, different service features were examined for their importance to the overall customer satisfaction based on an estimated regression model. The study found that most of the service features were below satisfactory rating, but Wynn Resorts stood out as the top performer among the four gaming companies. The regression model identified respect , smile and skill as the most important contributors to overall customer satisfaction. The findings suggest that to become a top gaming destination, Macao must strengthen its labor force quality in both technical and interpersonal skills

Fidelity susceptibility in the two-dimensional transverse field Ising and XXZ models

We study the fidelity susceptibility in the two-dimensional(2D) transverse field Ising model and the 2D XXZ model numerically. It is found that in both models, the fidelity susceptibility as a function of the driving parameter diverges at the critical points. The validity of the fidelity susceptibility to signal for the quantum phase transition is thus verified in these two models. We also compare the scaling behavior of the extremum of the fidelity susceptibility to that of the second derivative of the ground state energy. From those results, the theoretical argument that fidelity susceptibility is a more sensitive seeker for a second order quantum phase transition is also testified in the two models.Comment: 6 pages, 7 figure