Program

I.2 -- Invited, IWTCP-3

Date: Monday, 27 July 2015

Time: 11h15 - 11h50

Quantum field theory of interacting plasmon-photon-phonon system

Nguyen Van Hieu

Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam

This work is devoted to the construction of the quantum field theory of the interacting system of plasmon, photon and phonons on the basis of general fundamental principles of electrodynamics and quantum field theory of many-body systems. Since plasmon is a quasiparticle appeared as a resonance in the collective oscillation of the interacting electron gas in solids, the starting point is the total action functional of the interacting system comprising electron gas, electromagnetic field and phonon fields. By means of the powerful functional integral technique, this original total action is transformed into that of the system of the quantum fields describing plasmons, transverse photons, acoustic as well as optic longitudinal and transverse phonons. The collective oscillations of the electron gas is characterized by a real scalar field $\phi(x)$ called the collective oscillation field. This field is split into the static background field $\phi_0(x)$ and the fluctuation field $\zeta(x)$. The longitudinal phonon fields ${\bf Q}^{al}(x)$, ${\bf Q}^{ol}(x)$ are also split into the background fields ${\bf Q}^{al}_0(x)$, ${\bf Q}^{ol}_0(x)$ and dynamical fields ${\bf q}^{al}(x)$, ${\bf q}^{ol}(x)$ while the transverse phonon fields ${\bf Q}^{at}(x)$, ${\bf Q}^{ot}(x)$ themselves are dynamical fields ${\bf q}^{at}(x)$, ${\bf q}^{ot}(x)$ without background fields. After the canonical quantization procedure, the background fields $\phi_0(x)$, ${\bf Q}_0^{al}(x)$, ${\bf Q}_0^{ol}(x)$ remain the classical fields, while the fluctuation fields $\zeta(x)$ and dynamical phonon fields ${\bf q}^{al}(x)$, ${\bf q}^{at}(x)$, ${\bf q}^{ol}(x)$, ${\bf q}^{ot}(x)$ become quantum fields. In quantum theory, plasmon is the quantum of hermitian scalar field $\sigma(x)$ called the plasmon field, longitudinal phonons as complex spinless quasiparticles are the quanta of the effective longitudinal phonon hermitian scalar fields $\theta^a(x)$, $\theta^0(x)$ while transverse phonons are the quanta of the original hermitian transverse phonon vector fields ${\bf q}^{at}(x)$, ${\bf q}^{ot}(x)$. By means of the functional integral technique the original action functional of the interacting system comprising electron gas, electromagnetic field and phonon fields is transformed into the total action functional of the resultant system comprising plasmon scalar quantum field $\sigma(x)$, longitudinal phonon effective scalar quantum fields $\theta^a(x)$, $\theta^0(x)$ and transverse phonon vector quantum fields ${\bf q}^{at}(x)$, ${\bf q}^{ot}(x)$.

Presenter: Nguyen Van Hieu