Hidden Order and Symmetry Protected Topological States in Quantum Link Ladders

Area of Science:

• Condensed Matter Physics
• Quantum Simulation
• Topological Phases of Matter

Background:

• One-dimensional U(1) quantum-link models (QLMs) with spin-1/2 are generally topologically trivial.
• Exploring higher-dimensional or modified lattice structures can lead to novel topological phases.
• Symmetry-protected topological (SPT) phases are a key area of modern condensed matter research.

Purpose of the Study:

• To investigate the ground-state phase diagram of spin-1/2 U(1) QLMs in ladderlike lattices.
• To identify and characterize potential symmetry-protected topological (SPT) phases within these models.
• To propose an experimental scheme for realizing and detecting the SPT phase.

Main Methods:

• Theoretical analysis of spin-1/2 U(1) quantum-link models on ladder lattices.
• Investigation of ground-state properties and phase diagrams.
• Analysis of long-range string spin correlations to detect topological order.
• Proposal for experimental realization using single-component fermions in optical lattices with s and p bands.

Main Results:

• Spin-1/2 U(1) QLMs on ladderlike lattices exhibit an intriguing ground-state phase diagram.
• A distinct symmetry-protected topological (SPT) phase is identified within this phase diagram.
• Long-range string spin correlations serve as a robust indicator for the SPT phase.
• The proposed experimental scheme utilizing fermions in optical lattices is viable for realizing the SPT phase.

Conclusions:

• Ladderlike lattice implementations of spin-1/2 U(1) QLMs can host symmetry-protected topological phases.
• The identified SPT phase is experimentally accessible through adiabatic preparation in optical lattices.
• This work provides a pathway for the experimental exploration of topological phases in quantum-link models.