Creating Spin-One Fermions in the Presence of Artificial Spin–Orbit Fields: Emergent Spinor Physics and Spectroscopic Properties

Kürkçüoğlu, Doğa Murat; Melo, C. A. R. Sá de

doi:10.1007/s10909-018-1852-0

Cited by 5 publications

(4 citation statements)

References 32 publications

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“…Such techniques may allow explorations of deep connections to SU(3) symmetric interactions in the context of color-superconductivity of quark-matter. Furthermore, when color-flip and color-orbit fields are considered in systems consisting of three internal states of fermionic isotopes of Lithium, Potassium or Ytterbium [57,58], even the simple limits of: a) single-channel interactions g RG = g GB = 0 and g RB = 0 (a RG = a GB = 0 and a RB = 0) can lead to color-superfluidity [57] or b) no interactions at all g RG = g GB = g RB = 0 (a RG = a GB = a RB = 0) can lead to non-trivial spinor physics [58].…”

Section: B Self-consistency Equationsmentioning

confidence: 99%

Color superfluidity of neutral ultracold fermions in the presence of color-flip and color-orbit fields

Kürkçüoğlu

Melo

2018

Phys. Rev. A

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We describe how color superfluidity is modified in the presence of color-flip and color-orbit fields in the context of ultra-cold atoms, and discuss connections between this problem and that of color superconductivity in quantum chromodynamics. We study the case of s-wave contact interactions between different colors, and we identify several superfluid phases, with five being nodal and one being fully gapped. When our system is described in a mixed color basis, the superfluid order parameter tensor is characterized by six independent components with explicit momentum dependence induced by color-orbit coupling. The nodal superfluid phases are topological in nature, and the low temperature phase diagram of color-flip field versus interaction parameter exhibits a pentacritical point, where all five nodal color superfluid phases converge. These results are in sharp contrast to the case of zero color-flip and color-orbit fields, where the system has perfect U(3) symmetry and possesses a superfluid phase that is characterized by fully gapped quasiparticle excitations with a single complex order parameter with no momentum dependence and by inert unpaired fermions representing a non-superfluid component. In the latter case, just a crossover between a Bardeen-Cooper-Schrieffer and a Bose-Einstein-Condensation superfluid occurs. Furthermore, we analyse the order parameter tensor in a total pseudo-spin basis, investigate its momentum dependence in the singlet, triplet and quintet sectors, and compare the results with the simpler case of spin-1/2 fermions in the presence of spin-flip and spin-orbit fields, where only singlet and triplet channels arise. Finally, we analyse in detail spectroscopic properties of color superfluids in the presence of color-flip and color-orbit fields, such as the quasiparticle excitation spectrum, momentum distribution, and density of states to help characterize all the encountered topological quantum phases, which can be realized in fermionic isotopes of Lithium, Potassium and Ytterbium atoms with three internal states trapped.

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Section: B Self-consistency Equationsmentioning

confidence: 99%

Color superfluidity of neutral ultracold fermions in the presence of color-flip and color-orbit fields

Kürkçüoğlu

Melo

2018

Phys. Rev. A

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“…These techniques can also be applied to SU(3) fermions with three internal states (colors) and allow for the investigation of exotic topological insulating phases that arise in optical lattices when artificial magnetic, color-orbit and color-flip fields are varied. The present system in optical lattices expands the realm of phases beyond Fermi liquid and superfluid for SU (3) fermions in the presence of color-orbit and color-flip fields analyzed in the continuum or in harmonic traps [40,41].…”

Section: Introductionmentioning

confidence: 99%

“…Ultracold fermions loaded in optical lattices have become ideal systems to study related electronic phase diagrams and transport properties, because they provide a clean and well controlled playground to change various lattice parameters and external fields at the turn of a knob. While several experimental groups have worked mostly with Fermi isotopes 6 Li and 40 K using two internal states to study various aspects of interacting SU(2) fermions, there has been a growing interest in studying SU(N) generalizations of these systems. Examples of atomic SU(N) fermions found in nature are fermionic isotopes of closed shell atoms with two electrons in their outer electronic configuration.…”

Section: Introductionmentioning

confidence: 99%

Eigenspectrum, Chern Numbers and Phase Diagrams of Ultracold Color-orbit Coupled SU(3) Fermions in Optical Lattices

Yau,

de Melo

2020

Preprint

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We study ultracold color fermions with three internal states Red, Green and Blue with SU(3) symmetry in optical lattices, when color-orbit coupling and color-flip fields are present. This system corresponds to a generalization of two-internal state fermions with SU(2) symmetry in the presence of spin-orbit coupling and spin-flipping Zeeman fields. We investigate the eigenspectrum and Chern numbers to describe different topological phases that emerge in the phase diagrams of color-orbit coupled fermions in optical lattices. We obtain the phases as a function of artificial magnetic, color-orbit and color-flip fields that can be independently controlled. For fixed artificial magnetic flux ratio, we identify topological quantum phases and phase transitions in the phase diagrams of chemical potential versus color-flip fields or color-orbit coupling, where the chirality and number of midgap edge states changes. The topologically non-trivial phases are classified in three groups: the first group has total non-zero chirality and exhibit only the quantum charge Hall effect; the second group has total non-zero chirality and exhibit both quantum charge and quantum color Hall effects; and the third group has total zero chirality, but exhibit the quantum color Hall effect. These phases are generalizations of the quantum Hall and quantum spin Hall phases for charged spin-1/2 fermions. Lastly, we also describe the color density of states and a staircase structure in the total and color filling factors versus chemical potential for fixed color-orbit, color-flip and magnetic flux ratio. We show the existence of incompressible states at rational filling factors precisely given by a gap-labelling theorem that relates the filling factors to the magnetic flux ratio and topological quantum numbers.

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“…The explicit forms of the operators are h z ( k) = 2t x sin(k T a x ) sin( kx a x ) and b z ( k) = 4t x sin 2 (k T a x /2) cos( kx a x ). The term b z ( k)J 2 z describes a momentum-dependent color-quadrupole (or pseudo-spinquadrupole) coupling, reflecting the entanglement of momentum and tensorial degrees of freedom [20][21][22]. The presence of the color fields h x , h z ( k) and b z ( k) breaks SU(3) symmetry, however the color-gauge transformation shows that SU(3) symmetry 1 is restored when h x = 0 for any value of k T .…”

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confidence: 99%

SU(3) vs. SU(2) fermions in optical lattices: Color-Hall vs. spin-Hall topological insulators

Yau

Melo

2021

EPL

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We contrast topological insulating phases of SU(3) and SU(2) fermions in optical lattices under artificial magnetic fields. For this purpose, we compare the phase diagram of chemical potential vs. color-flip fields for SU(3) colored fermions (D 10 representation) for fixed color-orbit coupling to the phase diagram of chemical potential vs. spin-flip fields for SU(2) spin-1/2 fermions (D 1 representation) for fixed spin-orbit coupling. To classify the emergent topological phases, we obtain the Chern matrix and identify three distinct topological invariants for SU(3) colored fermions: the charge-charge, the color-charge and the color-color Chern numbers. This is in sharp contrast to the SU(2) spin-1/2 case, where only two topological invariants are necessary: the charge-charge and the spin-charge Chern numbers. Although we focus on SU(3) colored and SU(2) spin-1/2 fermions, our results indicate the existence of three independent Chern numbers associated with the quantum Hall response for higher fermionic irreducible representations D p and D p0 (p > 1) of SU(2) and SU(3), respectively. We suggest to investigate this comparison using the internal states of ultracold Fermi atoms ytterbium-173 ( 173 Yb) and strontium-87 ( 87 Sr).

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Creating Spin-One Fermions in the Presence of Artificial Spin–Orbit Fields: Emergent Spinor Physics and Spectroscopic Properties

Cited by 5 publications

References 32 publications

Color superfluidity of neutral ultracold fermions in the presence of color-flip and color-orbit fields

Color superfluidity of neutral ultracold fermions in the presence of color-flip and color-orbit fields

Eigenspectrum, Chern Numbers and Phase Diagrams of Ultracold Color-orbit Coupled SU(3) Fermions in Optical Lattices

SU(3) vs. SU(2) fermions in optical lattices: Color-Hall vs. spin-Hall topological insulators

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