Bipartite entanglement in Auger ionisation of ${\text{ N }}_{2}$

Abstract

Quantum entanglement and its paradoxical properties are of paramount importance in quantum information theory. In recent years, there has been an increasing interest in the studies of high-dimensional quantum states and their impact on quantum communication as it can encode and process more data. Photonic entanglement is usually an evanescent property as it is destroyed easily by its interaction with an external environment. Electronic qubits are stable and can store information for a long time. However, qudit systems are more efficient, stable and allow noise robustness than qubit system. In this article, we investigate bipartite entanglement between doubly ionised molecular qudit and electronic qubit in the Auger emission process for $\hbox {N}_{{2}}$ molecule following the absorption of a single photon without observing spin-orbit interaction (SOI). In the absence of SOI, Russell–Saunders coupling (L-S coupling) is applicable. The entanglement properties are estimated on the basis of negativity of partial transpose of the density matrix for Auger ionisation. We find that the entanglement depends on the spins of the singly ionised excited states and doubly ionised states of the molecules as well as on the directions of spin quantisation and of ejection of Auger electrons. A significant effect on the variation of negativity due to the linear dichroism (LD) has also been observed.