The Abdus Salam ICTP-Strada Costiera 11, 34151, Trieste, Italy.
Phys Rev Lett. 2012 Oct 26;109(17):177201. doi: 10.1103/PhysRevLett.109.177201. Epub 2012 Oct 23.
We solve the Sherrington-Kirkpatrick model in a transverse field Γ deep in its quantum glass phase at zero temperature. We show that the glass phase is critical everywhere, exhibiting collective excitations with a gapless Ohmic spectral function. Using an effective potential approach, we interpret the latter as arising from disordered collective excitations behaving like weakly coupled, underdamped oscillators. For a small transverse field Γ, the low-frequency spectrum takes a form independent of the fluctuation strength Γ.
我们在零温度下，于 Sherrington-Kirkpatrick 模型的横场 Γ 深处解决了其量子玻璃相。我们表明，玻璃相在各处都是临界的，表现出具有无隙 Ohmic 谱函数的集体激发。利用有效势方法，我们将后者解释为源自无序集体激发，其行为类似于弱耦合、欠阻尼振荡器。对于小的横场 Γ，低频谱取与涨落强度 Γ 无关的形式。
