Renyi Entanglement Entropy of Molecules: Interaction Effects and Signatures of Bonding

Abstract

Recent proposals of measuring bipartite Renyi entropy experimentally involve techniques that hold exactly for non-interacting quantum particles. Here we consider the difference between such measurements and the actual Renyi entropy for ground state fermion ab initio molecular systems. To calculate various entanglement measures we extended several different techniques for use with variational Monte Carlo, Hartree-Fock and quantum chemistry methods. Our results show that in systems with strong electron correlations the Renyi entropy may not be accurately determined with the proposed measurements. In addition, we find significant physical insight can be gained by calculating entanglement properties in molecular systems. We see that the Renyi entropy and the entanglement Hamiltonian encode information about the character of the covalent bonds in a molecular system and that such information may lead to better descriptions of bonded systems that have been traditionally hard to describe with standard techniques. In particular our results for the C${}_2$ dimer suggests all eight valence electrons play a significant role in covalent bonding.

arXiv comment8 pages, 4 figures

Cited by in corpus (5)

• Modern Approaches to Exact Diagonalization and Selected Configuration Interaction with the Adaptive Sampling CI Method
• From Ansätze to Z-gates: a NASA View of Quantum Computing
• A Rényi entropy perspective on topological order in classical toric code models
• A Path Integral Ground State Monte Carlo Algorithm for Entanglement of Lattice Bosons
• Entanglement in topological systems