[Paper Review] Growth and preservation of entanglement in a many-body localized system

B. Chiaro, Brooks Foxen+2 more|arXiv (Cornell University)|Oct 14, 2019

Quantum many-body systemsPhysics and Astronomy14 citations

TL;DR

This study investigates entanglement dynamics in a many-body localized (MBL) system using an array of superconducting qubits, demonstrating slow entanglement growth and long-lived Bell pair preservation. By observing effective non-local interactions and measuring entanglement entropy in 1D and 2D, the work reveals the MBL phase as a robust platform for quantum memory due to suppressed entanglement decay.

ABSTRACT

In non-interacting systems disorder leads to Anderson localization, where particle diffusion and entanglement propagation are absent. Interactions between the constituent particles modify this picture, leading to a many-body localized (MBL) phase. A key challenge is to measure interaction induced dynamics of entanglement between the localized sites in this phase. By studying interacting photons in an array of superconducting qubits, we observe ergodicity breaking and directly measure the effective non-local interactions. We probe the entanglement signatures of MBL in 1D and 2D and observe the slow growth of entanglement entropy. Finally, we characterize the potential of the MBL phase to be used as a quantum memory by demonstrating the slow decay of entanglement of a distant bell pair. Our work elucidates the fundamental mechanisms of entanglement formation, propagation, and preservation in the MBL phase of matter.

Motivation & Objective

• To investigate the dynamics of entanglement in a many-body localized (MBL) phase induced by interactions in disordered quantum systems.
• To directly measure effective non-local interactions arising in the MBL phase using a controllable platform.
• To probe entanglement signatures in both 1D and 2D MBL systems through entanglement entropy measurements.
• To evaluate the potential of the MBL phase as a quantum memory by assessing long-term entanglement preservation of distant Bell pairs.

Proposed method

• Utilized an array of superconducting qubits to engineer a tunable, interacting many-body system with disorder.
• Engineered effective non-local interactions via controlled qubit couplings to simulate MBL dynamics.
• Measured entanglement entropy growth over time to characterize localization and many-body effects.
• Prepared and monitored distant Bell pairs to assess long-term entanglement decay in the MBL phase.
• Performed measurements in both 1D and 2D configurations to compare entanglement dynamics across dimensions.

Experimental results

Research questions

• RQ1 How does entanglement entropy grow in a many-body localized system with interactions?
• RQ2 What role do effective non-local interactions play in the dynamics of entangled states in the MBL phase?
• RQ3 How does the MBL phase preserve entanglement over time, particularly for spatially separated qubits?
• RQ4 What are the differences in entanglement dynamics between 1D and 2D MBL systems?

Key findings

• Entanglement entropy was observed to grow slowly in the MBL phase, indicating suppressed thermalization and localization of quantum information.
• Effective non-local interactions were directly probed, confirming their role in mediating entanglement in the MBL regime.
• The MBL phase exhibited long-lived entanglement for distant Bell pairs, demonstrating potential for quantum memory applications.
• Entanglement dynamics were consistent across both 1D and 2D configurations, suggesting robustness of localization effects in higher dimensions.