Unconventional fermionic pairing states in a monochromatically tilted optical lattice

Abstract

We study the one-dimensional attractive Fermionic Hubbard model under the influence of periodic driving with the time-dependent density matrix renormalization group method. We show that the system can be driven into an unconventional pairing state characterized by a condensate made of Cooper-pairs with a finite center-of-mass momentum similar to a Fulde-Ferrell state. We obtain results both in the laboratory and the rotating reference frames demonstrating that the momentum of the condensate can be finely tuned by changing the ratio between the amplitude and the frequency of the driving. In particular, by quenching this ratio to the value corresponding to suppression of the tunnelling and the Coulomb interaction strength to zero, we are able to "freeze" the condensate. We finally study the effects of different initial conditions, and compare our numerical results to those obtained from a time-independent Floquet theory in the large frequency regime. Our work offers the possibility of engineering and controlling unconventional pairing states in fermionic condensates.

Manipulating Cooper pairs with a controllable momentum in periodically driven degenerate Fermi gases

“…We emphasize that the synthetic FF superfluids in our proposal bear the following two features: (i) the magnitude of Q is proportional to the parameter η, which stems from the wavelength of lasers that generate the driven field; (ii) the direction of Q is governed by the same lasers' direction. The two features differentiate this proposal from a piece of earlier Floquet engineering work [28], in which, like many other pieces of cold-atom works on FF superfluids, the pairing momentum is evidenced by the self-consistently solution, and cannot be directly determined by the driven field. Our proposal facilitates the manipulation of the pairing momentum in the synthetic FF phase, providing a simpler method to directly control not only its magnitude but also the direction.…”

Ultra‐Fast Control of Magnetic Relaxation in a Periodically Driven Hubbard Model

“…It also shows that conventional MPS time evolution based on Trotterized two-site unitary operations works as well as the previously-used Krylov-space algorithms [17,34], since with both methods similar timescales are reached with comparable computational effort. This motivates the use of our approach for analyzing how to manipulate and enhance, by external periodic driving, different types of ordered states in high-dimensional lattices such as charge-density waves and superconducting phases, for repulsive [22] and attractive [48,49] fermionic models.…”

Controllable finite-momenta dynamical quasicondensation in the periodically driven one-dimensional Fermi-Hubbard model

“…obtained by summing over all blocks m. The (−1) m factor in J(ν, Ω) arises because the hopping of a doublon consists of two single particle hops in the same direction, as in Fig. 2 Consequently, the effective model has a driving induced anisotropy that breaks the η-SU(2) symmetry of the undriven model [80,85]. The reason for this is that the effective model describes charge degrees of freedom and the driving couples directly to charge.…”