Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, D-01187 Dresden, Germany.
Phys Rev Lett. 2010 Jul 30;105(5):054102. doi: 10.1103/PhysRevLett.105.054102. Epub 2010 Jul 27.
We investigate anomalous energy transport processes in the Fermi-Pasta-Ulam β lattice, in particular, the maximum sound velocity of the relevant weakly damped energy carriers. That velocity is numerically resolved by measuring the propagating fronts of the correlation functions of energy-momentum fluctuations at different times. We use fixed boundary conditions and stochastic heat baths. The numerical results are compared with the theoretical predictions of the sound velocities for solitons and effective (renormalized) phonons, respectively. Excellent agreement has been found for the prediction of effective long wavelength phonons, giving strong evidence that the energy carriers should be effective phonons rather than solitons.
我们研究了费米-帕斯塔-乌拉姆β晶格中的异常能量输运过程，特别是相关弱阻尼能量载体的最大声速。通过测量不同时间的能量-动量涨落相关函数的传播前沿，数值上解决了这个速度问题。我们使用固定边界条件和随机热浴。数值结果分别与孤子和有效（重整化）声子的声速理论预测进行了比较。有效长波声子的预测得到了很好的一致性，有力地证明了能量载体应该是有效声子而不是孤子。
