Quantifying electron-nuclear spin entanglement dynamics in central-spin systems using one-tangles

TL;DR

This paper extends the use of the one-tangling power metric to quantify and optimize electron-nuclear spin entanglement dynamics in various central-spin systems, including quantum dots and color centers, with implications for quantum information processing.

Contribution

It generalizes previous findings to systems with higher nuclear spins and provides a practical procedure to maximize entanglement and coherence in quantum dot systems.

Findings

Identified parameter regimes for maximal entanglement in quantum dots.

Demonstrated generation of targeted spin entanglement using dynamical decoupling.

Provided a method to compute electron spin dephasing times with spin echo sequences.

Abstract

Optically-active solid-state systems such as self-assembled quantum dots, rare-earth ions, and color centers in diamond and SiC are promising candidates for quantum network, computing, and sensing applications. Although the nuclei in these systems naturally lead to electron spin decoherence, they can be repurposed, if they are controllable, as long-lived quantum memories. Prior work showed that a metric known as the one-tangling power can be used to quantify the entanglement dynamics of sparse systems of spin-1/2 nuclei coupled to color centers in diamond and SiC. Here, we generalize these findings to a wide range of electron-nuclear central-spin systems, including those with spin > 1/2 nuclei, such as in III-V quantum dots (QDs), rare-earth ions, and some color centers. Focusing on the example of an (In)GaAs QD, we offer a procedure for pinpointing physically realistic parameter regimes that yield maximal entanglement between the central electron and surrounding nuclei. We further harness knowledge of naturally-occurring degeneracies and the tunability of the system to generate maximal entanglement between target subsets of spins when the QD electron is subject to dynamical decoupling. We also leverage the one-tangling power as an exact and immediate method for computing QD electron spin dephasing times with and without the application of spin echo sequences, and use our analysis to identify coherence-sustaining conditions within the system.