Fig. 3: Temperature dependence of INS spectral parameters and quantum Fisher information (FQ).
From: High-temperature quantum coherence of spinons in a rare-earth spin chain
A Life-time broadening parameter as a function of temperature. Dashed line is instrumental resolution HWHM (= 0.013 meV) calculated for E = 0.5 meV. Solid curve is a fit to Arrhenius-type exponential function as described in the text. The inset shows fitted exchange interaction, J, and integrated intensity, \(\langle {S}_{z}^{2}\rangle\), at different temperatures; horizontal lines indicate nominal values, J = 0.21 meV21,22 and \(\langle {S}_{z}^{2}\rangle=1/4\). B Coherence length calculated using the spinon dispersion and extracted lifetime. Solid and dashed lines are asymptotic Arrhenius and resolution-limited behaviors as in (A). C Wave-vector dependence of the QFI, FQ(L), at various temperatures. Dashed curve is an approximation to asymptotic zero-temperature limit calculated from DMRG data at 200 mK as described in the text. D Temperature dependence of maximal quantum Fisher information, FQ(L = 1). Dashed black line is a power-law fit to the data in T ≥ 2 K range capturing asymptotic high-temperature behavior, FQ ~ ( J/T)n, with n = 2. Dashed red curve, shown in the region below TN = 0.8 K (shaded), is a fit of DMRG data below 4 K to a logarithmic dependence, \({F}_{Q}={\left[\ln (aJ/{k}_{B}T)\right]}^{\alpha }\), with J = 0.21 meV and fitting parameters a = 1.55(2) and α = 1.04(1), illustrating the low-T asymptotic behavior; in YbAlO3 it is arrested by static order below TN, where part of the excitation spectrum condenses into elastic Bragg peaks that do not contribute to QFI. Error bars represent one SD and, where not visible, are smaller than the symbol size.
