[Paper Review] Interspecies entanglement with impurity atoms in a bosonic lattice gas

Saubhik Sarkar, S. McEndoo+2 more|arXiv (Cornell University)|May 4, 2018

Cold Atom Physics and Bose-Einstein Condensates3 citations

TL;DR

This study investigates how interspecies entanglement between impurity atoms and a bosonic lattice gas affects measurements on either species, particularly in strongly interacting one-dimensional systems. Using analytical few-particle methods and density matrix renormalization group (DMRG) simulations, it shows that impurity dynamics can probe many-body states of the majority species, while also identifying parameter regimes where entanglement is minimized to enable non-invasive probing.

ABSTRACT

The dynamics of impurity atoms introduced into bosonic gases in an optical lattice have generated a lot of recent interest, both in theory and experiment. We investigate to what extent measurements on either the impurity species or the majority species in these systems are affected by their interspecies entanglement. This arises naturally in the dynamics and plays an important role when we measure only one species. We explore the corresponding effects in strongly interacting regimes, using a combination of few-particle analytical calculations and Density Matrix Renormalisation group methods in one dimension. We identify how the resulting effects on impurities can be used to probe the many-body states of the majority species, and separately ask how to enter regimes where this entanglement is small, so that the impurities can be used as probes that do not significantly affect the majority species. The results are accessible in current experiments, and provide important considerations for the measurement of complex systems with using few probe atoms.

Motivation & Objective

• To understand how interspecies entanglement between impurity atoms and a bosonic lattice gas influences measurements on either species.
• To determine how impurity dynamics can be used to probe the many-body states of the majority bosonic species.
• To identify experimental regimes where entanglement is minimized, enabling impurities to act as non-disturbing probes.
• To provide experimentally accessible insights into measuring complex quantum many-body systems using few probe atoms.

Proposed method

• Combines few-particle analytical calculations with one-dimensional density matrix renormalization group (DMRG) methods to study strongly correlated regimes.
• Models the dynamics of impurity atoms in a bosonic optical lattice, focusing on the emergence of interspecies entanglement.
• Analyzes measurement outcomes on either the impurity or majority species to assess the impact of entanglement.
• Identifies control parameters—such as interaction strength and lattice depth—that tune the degree of entanglement.
• Uses DMRG to simulate strongly interacting systems where analytical solutions are limited.

Experimental results

Research questions

• RQ1 How does interspecies entanglement affect the measurement of impurity or majority species in a bosonic lattice gas?
• RQ2 In what parameter regimes can entanglement between impurities and the majority species be minimized?
• RQ3 Can impurity dynamics serve as a reliable probe of the many-body state of the bosonic background?
• RQ4 What are the measurable signatures of entanglement in the dynamics of impurity atoms?

Key findings

• Interspecies entanglement significantly influences measurement outcomes when only one species is observed, particularly in strongly interacting regimes.
• Impurity dynamics can be used to probe the many-body correlations of the underlying bosonic lattice gas.
• Regimes exist where entanglement is suppressed, allowing impurities to act as non-invasive probes of the majority system.
• The results are accessible in current ultracold atom experiments, enabling direct testing of theoretical predictions.