Using Kondo entanglement to induce spin correlations between disconnected quantum dots

TL;DR

This paper demonstrates that Kondo entanglement can transfer spin information between disconnected quantum dots, creating transient entangled states useful for quantum information processing.

Contribution

It introduces a method to generate and analyze transient spin entanglement between disconnected quantum dots via Kondo entanglement, using a double quantum dot system and time-dependent density matrix renormalization group.

Findings

Partially entangled states can be formed during transient dynamics.

Entanglement is destroyed in the stationary state.

The stability of transient entanglement is demonstrated.

Abstract

We investigate the entanglement between the spins of two quantum dots that are not connected at once to the same system. Quantum entanglement between localized spins is an essential property for the development of quantum computing and quantum information. It is for this reason that generating and controlling an entangled state between quantum dots received great attention in the later years. In this work, we show that the information on the spin orientation of a quantum dot can be kept, using the Kondo entanglement, in a reservoir of electrons. Then, this information can be transmitted to another dot after the first dot has been uncoupled from the reservoirs. We use a double quantum dot system in a parallel geometry to construct the initial state, where each dot interacts with reservoirs of different symmetries. We chose a phase in the couplings to induce an antiferromagnetic spin correlation between the dots. The time evolution of the initial state has been analyzed using the time-dependent density matrix renormalization group method. We found that a partially entangled state between the dots can be obtained, even if they are not connected at the same time. This entangled state is formed just during the transient and is destroyed in the stationary state. The stability of the state found in the transient is shown. To understand the details of these phenomena, a canonical transformation of the real space is used.