Pulse and quench induced dynamical phase transition in a chiral multiferroic spin chain

TL;DR

This paper investigates the quantum dynamics and phase transitions in a chiral multiferroic spin chain under ultrashort THz pulses and electric field quenches, revealing robust entanglement and controllable dynamical transitions.

Contribution

It introduces analytical and numerical methods to analyze pulse and quench induced dynamical phase transitions in a chiral multiferroic spin chain, highlighting controllability via electric field pulses.

Findings

Partial loss of pair concurrence in incommensurate states

Robust many-particle entanglement and chirality in incommensurate phase

Confirmation of phase transition up to 40 spins

Abstract

Quantum dynamics of magnetic order in a chiral multiferroic chain is studied. We consider two different scenarios: Ultrashort terahertz (THz) excitations or a sudden electric field quench. Performing analytical and numerical exact diagonalization calculations we trace the pulse induced spin dynamics and extract quantities that are relevant to quantum information processing. In particular, we analyze the dynamics of the system chirality, the von Neumann entropy, the pairwise and the many body entanglement. If the characteristic frequencies of the generated states are non-commensurate then a partial loss of pair concurrence occurs. Increasing the system size this effect becomes even more pronounced. Many particle entanglement and chirality are robust and persist in the incommensurate phase. To analyze the dynamical quantum transitions for the quenched and pulsed dynamics we combined the Weierstrass factorization technique for entire functions and Lanczos exact diagonalization method. For a small system we obtained analytical results including the rate function of Loschmidt echo. Exact numerical calculations for a system up to 40 spins confirm phase transition. Quench- induced dynamical transitions have been extensively studied recently. Here we show that related dynamical transitions can be achieved and controlled by appropriate electric field pulses.