Quantum Dynamics of Polaron Formation.pdfVIP

Quantum Dynamics of Polaron Formation Li-Chung Ku1,2 and S. A. Trugman1 1 Theoretical Division, Los Alamos National Laboratory, 3 0 Los Alamos, New Mexico 87545, U.S.A. 0 2 2Department of Physics, University of California, t c Los Angeles, California 90024, U.S.A. O 9 (Dated: February 2, 2008) ] Abstract l e r- The formation of a polaron quasiparticle from a bare electron is studied in the framework of t s t. the Holstein model of electron-phonon coupling. Using Schrodinger’s¨ formalism, we calculate the a m time evolution of the distribution of the electron and phonon density, lattice deformation, and the - d electron-phonon (el-ph) correlation functions in real space. The quantum dynamical nature of the n o phonons is preserved. The polaron formation time is related to the dephasing time of the continuum c [ of unbound phonon excited states in the spectral function, which depends on the phonon frequency 1 v and the el-ph coupling strength. As the el-ph coupling increases, qualitative changes in polaron 6 2 formation occur when the one-phonon polaron bound state forms. In the adiabatic regime, we find 2 0 that a potential barrier between the quasi-free and heavy polaron states exists in both 2D and 3D, 1 3 which is crucial for polaron formation dynamics. We compare to recent experiments. 0 / t a m PACS numbers: 71.38.-k, 63.20-e, and 78.47.+p - d n o c : v i X r a 1 The polaron formation problem not only bears fundamental inte