Pairing correlations in two-dimensional strongly correlated systems

The nature of the normal phase of strongly correlated fermionic systems is an outstanding question in quantum many-body physics. We used spatially resolved radio-frequency spectroscopy to measure pairing energy of fermions across a wide range of temperatures and interaction strengths in a two-dimensional gas of ultracold fermionic atoms. We observed many-body pairing at temperatures far above the critical temperature for superfluidity. In the strongly interacting regime, the pairing energy in the normal phase considerably exceeds the intrinsic two-body binding energy of the system and shows a clear dependence on local density. This implies that pairing in this regime is driven by many-body correlations, rather than two-body physics. Our findings show that pairing correlations in strongly interacting two-dimensional fermionic systems are remarkably robust against thermal fluctuations.The nature of the normal phase of strongly correlated fermionic systems is an outstanding question in quantum many-body physics. We used spatially resolved radio-frequency spectroscopy to measure pairing energy of fermions across a wide range of temperatures and interaction strengths in a two-dimensional gas of ultracold fermionic atoms. We observed many-body pairing at temperatures far above the critical temperature for superfluidity. In the strongly interacting regime, the pairing energy in the normal phase considerably exceeds the intrinsic two-body binding energy of the system and shows a clear dependence on local density. This implies that pairing in this regime is driven by many-body correlations, rather than two-body physics. Our findings show that pairing correlations in strongly interacting two-dimensional fermionic systems are remarkably robust against thermal fluctuations.

arXiv:1705.10577ScienceDec 21, 201751 citations

Pair correlations in two-dimensional systems

I. L. Genkin, Z. N. Chumak, O. V. Chumak

Jan 1, 19770 citations

Defect-mediated pairing and dissociation of strongly correlated electrons in low-dimensional lattices

Vincent Pouthier, Saad Yalouz

We study the quantum dynamics of a strongly correlated electron pair in a one-dimensional lattice, focusing on the occurrence of local dissociation/pairing mechanisms induced by a site energy defect. To this end, we simulate the time evolution of two interacting electrons on a finite-size chain governed by an extended Hubbard Hamiltonian including on-site Coulomb repulsion $U$ and nearest-neighbor interaction $V$ , along with single-electron hopping $J$ . By introducing a local site energy defect with amplitude $\mathrm{\ensuremath{\Delta}}$, we show that a transition between spatially paired/dissociated electrons can occur in the vicinity of this site. Such mechanisms arise in a strongly correlated regime with nonzero nearest-neighbor Coulomb interactions and under the conditions $(U\ensuremath{\sim}V\ensuremath{\sim}\mathrm{\ensuremath{\Delta}})\ensuremath{\gg}J$. To rationalize these phenomena, we reformulate the two-electron dynamics of the original Hubbard chain as an effective single-particle problem on a two-dimensional network. Within this framework, we show that the pairing/dissociation dynamics are driven by resonances between two distinct families of two-electron eigenstates: (i) states with two spatially well-separated electrons with one located at the site defect, and (ii) states with a locally bound electron located away from the defect. At resonance, these states hybridize, allowing transitions from locally paired to dissociated electrons---and vice versa---in the vicinity of the defect. These results provide further insights into exotic pairing phenomena in strongly correlated electronic systems and may have implications for the design of tunable many-body states in low-dimensional quantum materials.We study the quantum dynamics of a strongly correlated electron pair in a one-dimensional lattice, focusing on the occurrence of local dissociation/pairing mechanisms induced by a site energy defect. To this end, we simulate the time evolution of two interacting electrons on a finite-size chain governed by an extended Hubbard Hamiltonian including on-site Coulomb repulsion $U$ and nearest-neighbor interaction $V$, along with single-electron hopping $J$. By introducing a local site energy defect with amplitude $\mathrm{\ensuremath{\Delta}}$, we show that a transition between spatially paired/dissociated electrons can occur in the vicinity of this site. Such mechanisms arise in a strongly correlated regime with nonzero nearest-neighbor Coulomb interactions and under the conditions $(U\ensuremath{\sim}V\ensuremath{\sim}\mathrm{\ensuremath{\Delta}})\ensuremath{\gg}J$. To rationalize these phenomena, we reformulate the two-electron dynamics of the original Hubbard chain as an effective single-particle problem on a two-dimensional network. Within this framework, we show that the pairing/dissociation dynamics are driven by resonances between two distinct families of two-electron eigenstates: (i) states with two spatially well-separated electrons with one located at the site defect, and (ii) states with a locally bound electron located away from the defect. At resonance, these states hybridize, allowing transitions from locally paired to dissociated electrons---and vice versa---in the vicinity of the defect. These results provide further insights into exotic pairing phenomena in strongly correlated electronic systems and may have implications for the design of tunable many-body states in low-dimensional quantum materials.

Physical review. B./Physical review. BSep 12, 20250 citations

Pairing Correlations in Finite Fermionic Systems

H. Flocard

Springer eBooksJul 3, 20070 citations

Theory of Strongly Correlated Systems

Rishabh Jha

arXiv:2507.07195Lecture notes in physicsJan 1, 20260 citations

U

and nearest-neighbor interaction

V

, along with single-electron hopping

J

. By introducing a local site energy defect with amplitude $\mathrm{\ensuremath{\Delta}}$, we show that a transition between spatially paired/dissociated electrons can occur in the vicinity of this site. Such mechanisms arise in a strongly correlated regime with nonzero nearest-neighbor Coulomb interactions and under the conditions $(U\ensuremath{\sim}V\ensuremath{\sim}\mathrm{\ensuremath{\Delta}})\ensuremath{\gg}J$. To rationalize these phenomena, we reformulate the two-electron dynamics of the original Hubbard chain as an effective single-particle problem on a two-dimensional network. Within this framework, we show that the pairing/dissociation dynamics are driven by resonances between two distinct families of two-electron eigenstates: (i) states with two spatially well-separated electrons with one located at the site defect, and (ii) states with a locally bound electron located away from the defect. At resonance, these states hybridize, allowing transitions from locally paired to dissociated electrons---and vice versa---in the vicinity of the defect. These results provide further insights into exotic pairing phenomena in strongly correlated electronic systems and may have implications for the design of tunable many-body states in low-dimensional quantum materials.