Indirect Hamiltonian Identification through a small gateway

TL;DR

This paper demonstrates that Hamiltonian parameters in a quantum system can be identified indirectly through a small accessible part, even in cases of degeneracy, provided the coupling topology is known.

Contribution

It introduces a method for indirect Hamiltonian identification using minimal access points, including strategies for degenerate Hamiltonians with additional fields.

Findings

Hamiltonian can be identified indirectly through a small gateway

Degenerate Hamiltonians can be estimated with an extra field

Method works with known coupling topology

Abstract

Identifying the nature of interactions in a quantum system is essential in understanding any physical phenomena. Acquiring information on the Hamiltonian can be a tough challenge in many-body systems because it generally requires access to all parts of the system. We show that if the coupling topology is known, the Hamiltonian identification is indeed possible indirectly even though only a small gateway to the system is used. Surprisingly, even a degenerate Hamiltonian can be estimated by applying an extra field to the gateway.