Quantum Phases of Quadrupolar Fermi Gases in Optical Lattices

Abstract

We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities.

Lattice solitons with quadrupolar intersite interactions

“…Still larger moments were measured in long-lived metastable states of alkaline-earth-metal [68,69] and ytterbium [70] atoms ( 20 DÅ), and in alkaline diatoms [71] (up to 50 DÅ). As recently shown for fermions, such sizes for quadrupole moments are sufficient to generate new phases in quantum gases trapped in the OL [72]. Furthermore, it has been predicted that the QQI can be strongly amplified by means of optical vortices [73].…”

“…Ref. [72]. Finally, to estimate the range of physical parameters allowing the implementation of the present model, the magnitude of the quadrupole moment can be estimated for a complex built as a square with charges (+e,−e,+e,−e) set at its vertices, with linear size ε (e is the electron's charge).…”

Reservoir spectroscopy of5s5p3P2–5snStellmer1, Schreck2 2014Phys. Rev. A317441View full textAdd to dashboardCite

“…The frequencies and strengths of the transitions originating from the metastable states are needed to calculate the black-body radiation (BBR) shifts of a clock transition, which is particularly important for strontium [57,58]. Atoms in the 3 P 2 state can be used to study systems with quadrupolar interactions [42,44]. Furthermore, magnetic Feshbach resonances have been observed between atoms in the 3 P 2 and 1 S 0 states [59].…”

“…Quantum degenerate samples of Yb [7][8][9][10][11] and the alkaline-earth-metals Ca [12,13] and Sr [14][15][16][17][18][19][20] have opened new possibilities, such as the study of SU(N ) magnetism [21][22][23][24][25][26][27][28][29][30][31][32][33][34], novel schemes to simulate gauge fields [35][36][37][38][39][40], the engineering of interactions beyond contact interactions [41][42][43][44], the creation of driven-dissipative many-body states [45], the simulation of an extra dimension [46], and new ways to perform quantum computation [47][48][49][50][51].…”

Exotic roton excitations in quadrupolar Bose–Einstein condensates

“…Recently we introduced ultracold quantum gases of quadrupolar particles as a prospective platform for studying many-body phenomena [19][20][21]. Quadrupolar particles, such as ultracold homonuclear dimers, are prone to chemical reactions occurring for dipolar molecules [22].…”