Non localization of free electrons

Gaston Casanova

Yijie Mo, Jiaqing Huang, Yao Yao

We investigate the localization in a one-dimensional modified Peierls model with a non-adiabatic dynamic method. Different from the polaron scenario, here the localization stems from extensive conserved local quantities in the disorder-free lattice. Both the entanglement entropy and out-of-time-ordered correlator (OTOC) show the oscillating feature of dynamically generated localization. Although the strong interaction between electrons may suppress the dynamical features of the localization, but the effect of many-body localization is not observed. The role of disorder presented at finite temperature is discussed as well. The electrons diffuse in a classical manner. Benefitting from the indication of OTOC, it is found that the Anderson localization becomes dominant instead of dynamic localization as observed in disorder-free lattices.

Kaushik Ghosh

In this article we will demonstrate that the detection of electrons in an interference experiment with electrons is a transition between two Hilbert spaces caused by interactions with the detecting screen. The first Hilbert space is that of the free electrons before detection and the second is that of the bound electrons in the screen after detection. This transition can be described by unitary quantum-mechanical perturbation theory where the grand Hilbert space required to describe the electrons is the direct sum of these two Hilbert spaces. We can say an electron is detected at the screen only after the interaction between the two has caused an observable effect like an atomic transition. Detection of the electrons does not solely indicate modification of the quantum states taking place in the Hilbert space used to describe the electron before detection. It cannot be used to imply a non-unitary transformation of the quantum states belonging to this Hilbert space only. Similarly, emission of electrons from a material to free space is a transition from the set of bound states to the set of free states. This transition can be described by using time-dependent perturbation theory without referring to any non-unitary transformation. In both the cases, relevant transitions would be given by the time evolution of exact solutions of the interacting theory and rescind the requirement of introducing any non-unitary transformation. This interpretation may be extended to other measurement processes. We will conclude the article with a brief discussion on non-locality in quantum mechanics. This is based on the necessity of complex functions in quantum theory and perception of human brain on imaginary numbers.

U. Rößler

Pubudu S. Senanayake, Jon‐Paul R. Wells, Michael F. Reid +4 more

We model the dynamic behaviour observed for impurity-trapped excitons in SrF2:Yb2+ using transient photoluminescence enhancement induced via a two-frequency, sequential excitation process employing an UV optical parametric amplifier synchronized to an IR free electron laser (FEL). We observe sharp transitions interpreted as a change of state of the localized hole and broad bands interpreted as a change of state of the delocalized electron. Our modeling indicates that the 4f crystal-field interaction is 25% smaller than in CaF2. The photoluminescence enhancement transients are analyzed across a range of excitation frequencies using a system of rate equations. The temporal behavior is explained in terms of intra-excitonic relaxation, local lattice heating by the FEL, and liberation of electrons from trap states.

Mark P. Silverman