Two-Fluid Coexistence in a Spinless Fermions Chain with Pair Hopping

Area of Science:

• Condensed Matter Physics
• Quantum Many-Body Systems
• Low-Dimensional Materials

Background:

• Understanding emergent phenomena in one-dimensional (1D) quantum systems is crucial.
• Fermionic systems exhibit complex behaviors, including pairing and Luttinger liquid states.
• Investigating models with novel interactions, like pair hopping, can uncover new phases.

Purpose of the Study:

• To explore the phase diagram of a 1D model of spinless fermions with pair hopping.
• To identify and characterize novel quantum phases arising from pair hopping interactions.
• To elucidate the coexistence of different fermionic states within a single phase.

Main Methods:

• Numerical density-matrix renormalization-group (DMRG) calculations were extensively performed.
• A theoretical two-fluid model was developed to interpret the numerical findings.
• Analysis focused on identifying distinct fermionic liquid behaviors.

Main Results:

• A novel phase was discovered where a Luttinger liquid of paired fermions coexists with a Luttinger liquid of unpaired fermions.
• The coexistence is robust and characterized by distinct electronic fluid behaviors.
• The numerical results align with the predictions of the two-fluid model.

Conclusions:

• The 1D spinless fermion model with pair hopping hosts a unique coexistence phase.
• This phase provides a new platform for studying interacting quantum fluids.
• The findings contribute to the fundamental understanding of quantum phase transitions and emergent phenomena in 1D systems.