Entanglement and exotic superfluidity in spin-imbalanced lattices

Abstract

We investigate the properties of entanglement in one-dimensional fermionic lattices at the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid regime. By analyzing occupation probabilities, which are concepts closely related to FFLO and entanglement, we obtain approximate analytical expressions for the spin-flip processes at the FFLO regime. We also apply density matrix renormalization group calculations to obtain the exact ground-state entanglement of the system in superfluid and nonsuperfluid regimes. Our results reveal a breaking pairs avalanche appearing precisely at the FFLO-normal phase transition. We find that entanglement is non-monotonic in superfluid regimes, feature that could be used as a signature of exotic superfluidity.

Simulating Artificial 1D Physics with Ultra‐Cold Fermionic Atoms: Three Exemplary Themes

“…For this reason, the unconventional FFLO pairing in ultra‐cold 1D systems has recently been deeply investigated theoretically from various perspectives, for both confined [ 54–57 ] and lattice systems. [ 58–62 ] Quasi‐1D quantum simulators created with ultra‐cold neutral atoms constitute a highly controllable environment, where the Fermi surface mismatch can be precisely tuned by changing the spin composition of the initial population, rather than with external magnetic fields. [ 63–67 ] The relative spin populations can be tuned, for example, by driving radio‐frequency sweeps between the states at different powers.…”

Simulating artificial one-dimensional physics with ultra-cold fermionic atoms: three exemplary themes

“…In particular, the FFLO phase occupies a large part of the phase diagram in fermionic systems in one spatial dimension [37][38][39][40], making (quasi-)onedimensional systems a very good environment to search for the elusive FFLO state. For this reason, the unconventional FFLO pairing in ultra-cold one-dimensional systems has recently been deeply investigated theoretically from various perspectives, for both confined [41][42][43][44] and lattice systems [45][46][47][48][49]. Quasi-one-dimensional quantum simulators created with ultra-cold neutral atoms constitute a highly controllable environment, where the Fermi surface mismatch can be precisely tuned by changing the spin composition of the initial population, rather than with external magnetic fields [50][51][52][53][54].…”

Linear mapping between magnetic susceptibility and entanglement in conventional and exotic one-dimensional superfluids

“…Entanglement has also played a central role in bridging quantum information theory to different areas, as condensed-matter, high-energy and cold-atoms physics [4][5][6][7][8][9][10][11][12][13][14][15][16][17] . By investigating entanglement properties one can probe quantum phase transitions [18][19][20][21][22][23] and characterise quantum many-body states, including exotic states of matter as Fulde-Ferrel-Larkin-Ovchnnikov superfluidity (FFLO) [24][25][26][27][28][29][30] , many-body localization 31,32 and topological spin liquids 33 .…”