Quantum Degenerate Dipolar Fermi Gas

Abstract

The interplay between crystallinity and superfluidity is of great fundamental and technological interest in condensed matter settings. In particular, electronic quantum liquid crystallinity arises in the non-Fermi liquid, pseudogap regime neighboring a cuprate's unconventional superconducting phase 1 . While the techniques of ultracold atomic physics and quantum optics have enabled explorations of the strongly correlated, many-body physics inherent in, e.g., the Hubbard model 2 , lacking has been the ability to create a quantum degenerate Fermi gas with interparticle interactions-such as the strong dipole-dipole interaction 3 -capable of inducing analogs to electronic quantum liquid crystals. We report the first quantum degenerate dipolar Fermi gas, the realization of which opens a new frontier for exploring strongly correlated physics and, in particular, the quantum melting of smectics in the pristine environment provided by the ultracold atomic physics setting 4 . A quantum degenerate Fermi gas of the most magnetic atom 161 Dy is produced by laser cooling to 10 µK before sympathetically cooling with ultracold, bosonic 162 Dy. The temperature of the spin-polarized 161 Dy is a factor T /T F = 0.2 below the Fermi temperature T F = 300 nK. The co-trapped 162 Dy concomitantly cools to approximately T c for Bose-Einstein condensation, thus realizing a novel, nearly quantum degenerate dipolar Bose-Fermi gas mixture.Quantum soft phases are states of quantum matter intermediate between canonical states of order and disorder, and may be considered the counterparts of liquid crystalline and glassy states in classical (soft) condensed matter physics. Such phases tend to arise under competition between short and long-range interactions and often result in the non-Fermi liquid, strongly correlated behavior manifest in some of the most interesting electronic materials of late: high-T c cuprate superconductors, strontium ruthenates, 2D electron gases, and iron-based superconductors 5 . Recent theory suggests the long-range, anisotropic dipole-dipole interaction (DDI) among atoms in a degenerate Fermi gas, confined in an harmonic trap or optical lattice, may also induce transitions to states beyond the now-familiar insulating, metallic, and superfluid. Namely, phases that break rotational, translational, or point group symmetries may emerge in a manner akin to those found in classical liquid crystals, e.g., the nematic and smectic 1 . Degenerate gases of highly magnetic fermionic atoms, such as 161 Dy, may shed light on QLC physics without unwanted solid state material complexity, disorder, and dynamical lattice distortions. Uniaxial (meta-nematic) 6 and biaxial nematic 7 distortions of the Fermi surface of a harmonically trapped gas in the presence of a polarizing field may be observable as well as meta-nematic and smectic phases in 2D anisotropic optical lattices [8][9][10] . An exciting prospect lies in the possibility of achieving spontaneous magnetization in dipolar systems coupled with nematic order 11,12 . Additionally,...

Bright solitons in a two-dimensional spin-orbit-coupled dipolar Bose-Einstein condensate

“…It is essential to note that although the relevant interaction in most experiments with cold atomic gases is contact, increasing interest has been focused on the atoms with * chuanwei.zhang@utdallas.edu large magnetic moments that possess dipole-dipole interactions [17,20,21]. In fact, the Bose-Einstein condensation of several dipolar atoms such as Chromium [22][23][24], Dysprosium [25], and Erbium [26], as well as the degeneracy of a dipolar Fermi gas [27,28] have been observed in experiments.…”

Dipoles on a two-leg ladder

“…Alternatively, one can also use neutral atoms with sizable magnetic dipole moments [70][71][72][73][74] or Rydberg atoms [75][76][77] . Measuring the bulk ordering such as Ising and string orders seems very realistic given current experimental developments using singlesite addressing 78,79 .…”

Controllable quantum spin glasses with magnetic impurities embedded in quantum solids

“…As an impurity species we choose dysprosium -the most magnetic atom in the periodic table. Its bosonic and fermionic isotopes have been recently brought to quantum degeneracy 27,28 , which provides us a benchmark for comparison with other ultracold atomic experiments. We note that using matrix-isolated polar molecules 29 can potentially result in stronger dipole-dipole interactions between the impurities, however, decoherence due to coupling to phonons is also stronger for species possessing an electric dipole moment 30,31 .…”