BCS-BEC crossover induced by a synthetic non-Abelian gauge field

Vyasanakere, Jayantha P.; Zhang, Shizhong; Shenoy, Vijay B.

doi:10.1103/physrevb.84.014512

Cited by 170 publications

(254 citation statements)

References 19 publications

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“…Note Added: During preparing this paper, we became aware of three preprints, in which similar problem has been addressed [13][14][15]. For the overlap part, our results agree with each other.…”

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confidence: 80%

Spin-Orbit Coupled Fermi Gases across a Feshbach Resonance

2011

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In this letter we study both ground state properties and the superfluid transition temperature of a spin-1/2 Fermi gas across a Feshbach resonance with a synthetic spin-orbit coupling, using meanfield theory and exact solution of two-body problem. We show that a strong spin-orbit coupling can significantly enhance the pairing gap for 1/(kFas) 0 due to increased density-of-state. Strong spinorbit coupling also significantly enhances the superfluid transition temperature when 1/(kFas) 0, while suppresses it slightly when 1/(kFas) 0. The universal interaction energy and pair size at resonance are also discussed.During the last few years, studies of ultracold Fermi gases across a Feshbach resonance (FR) have brought a lot of excitements to physics [1]. On a separate development, recent experimental breakthrough on synthetic gauge field has open up a lot of new opportunities to cold atom physics [2,3]. One application of this technique is to engineer an effective spin-orbit coupling (SOC) in cold atom system [4]. Very recently, a pioneer experiment in NIST has already achieved a restricted class of spin-orbit coupled BEC of 87 Rb atoms [3]. Theoretically, even the mean-field study of boson condensate with SOC has revealed many interesting physics [5][6][7]. For fermions, a concrete scheme has also been proposed for generating SOC in 40 K atom in the regime where a magnetic FR is available [8], and the experiment of implementing this proposal is now going on in the laboratory. However, a theoretical study of spin-orbit coupled Fermi gases across a FR is still lacking.In the absence of SOC, a Fermi gas across a FR possesses three key physical properties: i) across a FR the system undergoes a crossover from a BCS type fermion superfluid to a BEC of molecules; ii) at the FR, it is a strongly interacting system and exhibits many universal behaviors; iii) nearby a FR, the transition temperature of fermion superfluid T c /T F is the highest one among all fermion superfluids (or superconductors). The question is that how these three properties evolve in the presence of SOC. For i), since now the pair wave-function has more complicated structure with both singlet and triplet components, and exhibits p-wave character in the helicity bases, one needs to investigate whether it is still a crossover or there is a phase transition in between. Even if it is still a crossover, how SOC affects it. For ii), since the strength of SOC introduces another length scale λ/k F , the universal constants at resonance now become universal functions of λ/k F , and we want to understand the behaviors of these functions. And for iii), the question is whether T c /T F will be enhanced or suppressed by SOC. (Here the units k F , E F and T F are the Fermi momentum, the Fermi energy and the Fermi temperature for non-interacting system without SOC. a s is the s-wave scattering length.)In this letter we address these issues using both meanfield (MF) theory and exact solution of two-body (TB) problem, and the main results are summarized as follows: (A1) T...

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confidence: 80%

Spin-Orbit Coupled Fermi Gases across a Feshbach Resonance

2011

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“…Generalizing conventional BEC-BCS crossover mean-field theory to the case with SO coupling and equal population n ↑ = n ↓ , one can show that the system remains gapped for all k F a s , although there are triplet p-wave components 60,61,62,63 , and the pair wave function obtained from the mean-field theory finally approaches the wave function of two-body bound state (i.e. molecule wave function) 60,62 .…”

Section: Spin-orbit Coupled Fermi Gases Across a Feshbach Resonancementioning

confidence: 99%

Spin-Orbit Coupled Quantum Gases

Zhai

2012

Int. J. Mod. Phys. B

267

304

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In this review we will discuss the experimental and theoretical progresses in studying spin-orbit coupled degenerate atomic gases during the last two years. We shall first review a series of pioneering experiments in generating synthetic gauge potentials and spin-orbit coupling in atomic gases by engineering atom-light interaction. Realization of spin-orbit coupled quantum gases opens a new avenue in cold atom physics, and also brings out a lot of new physical problems. In particular, the interplay between spin-orbit coupling and inter-atomic interaction leads to many intriguing phenomena. Here, by reviewing recent theoretical studies of both interacting bosons and fermions with isotropic Rashba spinorbit coupling, the key message delivered here is that spin-orbit coupling can enhance the interaction effects, and make the interaction effects much more dramatic even in the weakly interacting regime.

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“…During the last few years these topics have gained an increasing interest for ultracold atomic gases [4][5][6][7][8] which represent the systems simulating many condensed matter phenomena. Recent experimental progress in the spin-orbit coupling (SOC) of degenerate atomic gases [9][10][11][12][13] has stimulated the theoretical studies of diverse new phases due to the SOC [8,[14][15][16][17], such as emergence of the stripe phase in atomic Bose-Einstein condensates (BECs) [18][19][20][21][22], or formation of unconventional bound states [23][24][25][26] and topological superfluidity [27] for atomic fermions. It was demonstrated that for the spin-orbit (SO) coupled BECs, the half-vortex (meron) ground states may develop in harmonic traps [28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Tunneling-assisted spin-orbit coupling in bilayer Bose-Einstein condensates

Sun

Wen²,

Liu³

et al. 2015

Phys. Rev. A

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Motivated by a goal of realizing spin-orbit coupling (SOC) beyond one-dimension (1D), we propose and analyze a method to generate an effective 2D SOC in bilayer BECs with laser-assisted interlayer tunneling. We show that an interplay between the inter-layer tunneling, SOC and intra-layer atomic interaction can give rise to diverse ground state configurations. In particular, the system undergoes a transition to a new type of stripe phase which spontaneously breaks the time-reversal symmetry. Different from the ordinary Rashba-type SOC, a fractionalized skyrmion lattice emerges spontaneously in the bilayer system without external traps. Furthermore, we predict the occurrence of a tetracritical point in the phase diagram of the bilayer BECs, where four different phases merge together. The origin of the emerging different phases is elucidated.

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BCS-BEC crossover induced by a synthetic non-Abelian gauge field

Cited by 170 publications

References 19 publications

Spin-Orbit Coupled Fermi Gases across a Feshbach Resonance

Spin-Orbit Coupled Fermi Gases across a Feshbach Resonance

Spin-Orbit Coupled Quantum Gases

Tunneling-assisted spin-orbit coupling in bilayer Bose-Einstein condensates

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