Instability in one-dimensional systems

Sujit Sarkar

Superconducting instability is studied for a one dimensional repulsive system of spinful fermions with double degenerate band. There is no evidence of insulating spin liquid or the D-Mott phase, for any generic fillings. A conventional spin gap phase without any gap in the charge sector (metallic spin gap) is predicted, which is the starting point to investigate the gapless superconducting instability.

Scott W. Heinekamp

Julián Rincón, K. A. Al-Hassanieh, Adrian E. Feiguin +1 more

We investigate the real-time dynamics of photoexcited electronic instabilities in a charge-transfer system model, using the time-dependent density matrix renormalization group method. The model of choice was the quarter-filled one-dimensional extended Peierls-Hubbard Hamiltonian interacting with classical few-cycle electromagnetic radiation. The results show that only one electronic instability drives the main features of the photogenerated time-dependent behavior. Indeed, the photoresponse of the system shows a large enhancement of the $4{k}_{F}$ (bond and charge) instability whereas the $2{k}_{F}$ state remains largely unaffected. This conclusion holds regardless of the nature of the optical excitations and whether the system is perturbed resonantly or not. Our results suggest potential applications of charge-transfer systems with slow phononic dynamics as optoelectronic switching devices.

Olivier Martin

Andrew J. Ferris, Matthew J. Davis, R. Geursen +2 more

We present a joint theoretical and experimental study of the dynamical instability of a Bose---Einstein condensate at the band edge of a one-dimensional optical lattice. The instability manifests as rapid depletion of the condensate and conversion to a thermal cloud. We consider the collisional processes that can occur in such a system, and undertake a thorough theoretical study of the dynamical instability in systems of different dimensionality. We find spontaneous scattering is an important part of this process, and thus the Gross-Pitaevskii equation is unable to accurately predict the dynamics in this system. Our beyond mean-field approach, known as the truncated Wigner method, allows us to make quantitative predictions for the processes of parametric growth and heating that are observed in the laboratory, and we find good agreement with the experimental results.

J. M. P. Carmelo, Pedro D Sacramento, D. Bozi +1 more