ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

jan. 17. péntek 10h15,
1111 Bp., Budafoki út 8., BME FIII. magasföldszint 1, szemináriumi szoba

Horacio Pastawski (Universidad Nacional de Córdoba, Argentina, Varga Imre
vendége):
Decoherence and emergent phenomena in quantum dynamical transport

The basic concepts of quantum dynamical transport of carriers rely on the
pioneering work of P. W. Anderson, R. Landauer, and M. Büttiker. Starting
from the renormalization procedures of the quantum field density Green’s
functions in the formalism of Keldysh and Kadanoff-Baym, it is easy to
describe open systems in the thermodynamic limit [1,2]. The requirement of
the conservation laws in the linear regime yields the Generalized
Landauer-Büttiker Equations (GLBE), equivalent to the Kirchhoff law for a
quantum circuit [3]. The GLBE accounts for quantum dynamics and decoherence
processes using a non-Hermitian Hamiltonian concatenated with a
self-consistent evolution of a generalized density. This enables to
describe emergent phenomena, of which the Quantum Dynamical Phase
Transition (QDPT) becomes a paradigmatic example [4]. However, the
numerical solution of the dynamics only becomes practical within the
“quantum-drift model” (DQM), which represents the “collapse” imposed by the
environmental interactions as a stochastic noise imposed upon Schrödinger
dynamics [5]. This procedure recovers all known results from other
approaches such as the Carmichael and Dalibard-Casting “quantum jumps”
model and the Haken-Strobl model. Moreover, the QDM has a fundamental
connection with the Ghirardi-Rimini- Weber stochastic the Schrödinger
equation. As a key practical aspect, only a single wave function (either
single particle or many-body) is stored, allowing the evaluation of
observables and their fluctuations. This has a very low computational cost
as compared with the GLBE or the Lindblad equation. We will mention the
main achievement in describing Giant Magnetoresistance (GMR), Sound
Amplification (SASER) [5], H2 dissociation in the Heyrovsky heterogeneous
catalysis [6] and even the “poised-realm” regime of biological
electron-transfer in proteins and DNA [7]. This tool could describe the
dynamics of electronic excitation induced in attosecond laser spectroscopy
and the puzzling observation of intrinsic irreversibility [8] in chaotic
many-body dynamics in Loschmidt echo/OTOC experiments in NMR.


[1] H. M. Pastawski, Classical and Quantum Transport from Generalized
Landauer-Büttiker Equations II: Time dependent tunneling. Phys. Rev. B 46,
4053 (1992).

[2] H. M. Pastawski, L. E. F. Foa Torres, and E. Medina, Electron-phonon
interaction and electronic decoherence in molecular conductors. Chem. Phys.
281, 257 (2002).

[3] C. J. Cattena, L. J. Fernández-Alcázar, R. A. Bustos-Marún, D. Nozaki,
and H. M. Pastawski, Generalized multi-terminal decoherent transport:
recursive algorithms and applications to SASER and giant magnetoresistance.
J. Phys.: Condens. Matter 26, 345304 (2014).

[4] H. M. Pastawski, Revisiting the Fermi Golden Rule: Quantum dynamical
phase transition as a paradigm shift. Physica B 398, 278(2007).

[5] L. J. Fernández-Alcázar and H. M. Pastawski, Decoherent time-dependent
transport beyond the Landauer-Büttiker formulation: A quantum-drift
alternative to quantum jumps. Phys. Rev. A 91, 022117 (2015)

[6] F. S. Lozano-Negro, M. A. Ferreyra-Ortega, D. Bendersky, L. J.
Fernández-Alcázar, and H. M. Pastawski, Simulating a catalyst induced
quantum dynamical phase transition of a Heyrovsky reaction with different
models for the environment. J. Phys. Condens. Matt. 34, 214006 (2022).

[7] F. S. Lozano-Negro, E. Alvarez Navarro, N. C. Chávez, F. Mattiotti, F.
Borgonovi, H. M. Pastawski, and G. L. Celardo, Universal stability of
coherently diffusive 1D systems with respect to decoherence. Phys. Rev. A
109, 042213 (2024).

[8] C. M. Sánchez, A. K. Chattah, and H. M. Pastawski, Emergent decoherence
induced by quantum chaos in a many-body system: A Loschmidt echo
observation through NMR. Phys. Rev. A 105, 052232 (2022).

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor