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Hidden String Order in a Hole Superconductor with Extended Correlated Hopping
Ravindra W Chhajlany1,2, Przemysław R Grzybowski2, Julia Stasińska1,3
1ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Barcelona, Spain.
Physical Review Letters
|June 18, 2016
Summary
Ultracold fermions in 1D optical lattices exhibit spin-charge separation due to a special Hubbard model. This leads to unique ground state order with a spin gap and nonlocal string order, persisting even away from ideal conditions.
Area of Science:
- Quantum physics
- Condensed matter physics
- Ultracold atomic gases
Background:
- Investigating ultracold fermions in optical lattices is crucial for understanding quantum many-body systems.
- Spin-dependent, nonoverlapping optical lattices present unique Hamiltonians, such as the nonstandard Hubbard model.
- Exploring exotic phenomena like spin-charge separation is a key goal in condensed matter physics.
Purpose of the Study:
- To analyze ultracold fermions in 1D optical lattices using a nonstandard Hubbard model.
- To investigate the system's behavior in the limit of kinetically constraining correlated hopping.
- To explore the emergence of spin-charge separation and associated ground state properties.
Main Methods:
- Exact mapping of Hamiltonian invariant subspaces to free spinless fermion chains.
- Analytical derivation of system properties for arbitrary filling.
- Numerical studies away from the integrable point to assess parameter dependence.
Main Results:
- The system exactly exhibits spin-charge separation in a specific limit.
- Ground state order is characterized by a spin gap and long-range nonlocal string order.
- Numerical simulations confirm the persistence of string order and spin gap, and show a transition to a ferromagnetic state.
Conclusions:
- The studied system provides an exact realization of spin-charge separation in ultracold fermions.
- The observed spin gap and nonlocal string order indicate unconventional superconductivity.
- The system's rich phase diagram includes a ferromagnetic state, highlighting its versatility for quantum simulations.
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