Optimal transfer of entanglement in oscillator chains in non-Markovian open systems

TL;DR

This paper demonstrates high-fidelity transfer of continuous-variable entangled states in oscillator chains using optimal control, showing that tuning oscillator frequencies can counteract environmental effects and that quantum memory can enhance transfer.

Contribution

It introduces a modified Krotov optimization approach for non-Markovian dynamics and shows that simple frequency tuning enables effective entanglement transfer despite environmental noise.

Findings

High-fidelity entanglement transfer achieved with frequency tuning.

Quantum memory effects can improve transfer fidelity.

Transfer method works without prior knowledge of initial state parameters.

Abstract

We considered the transfer of continuous-variable entangled states in coupled oscillator chains embedded in a generic environment. We demonstrate high-fidelity transfer via optimal control in two configurations - a linear chain and an X-shaped chain. More specifically, we use the Krotov optimization algorithm to design control fields that achieve the desired state transfer. Under the environmental memory effects, the Krotov algorithm needs to be modified, since the dissipative terms in non-Markovian dynamics are generally governed by the time-dependent system Hamiltonian. Remarkably, we can achieve high-fidelity transfer by simply tuning the frequencies of the oscillators while keeping the coupling strength constant, even in the presence of open-system effects. For the system under consideration, we find that quantum memory effects can aid in the transfer of entanglement and show improvement over the memoryless case. In addition, it is possible to target a range of entangled states, making it unnecessary to know the parameters of the initial state beforehand.