Direct observation of effective ferromagnetic domains of cold atoms in a shaken optical lattice

Parker, Colin; Ha, Li-Chung; Chin, Cheng

doi:10.1038/nphys2789

Cited by 244 publications

(357 citation statements)

References 29 publications

(33 reference statements)

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“…For example, taking a typical density of the 40 K gas 33,34 and the potential depths of the optical lattice to be V s /E R ¼ 3 and V p /2E R ¼ 5 for s and p orbitals (see the lattice potentials in Methods), respectively, we estimate the KosterlitzThouless transition temperature can reach around 100 nK or higher, being within the experimental temperature scope 35 . 36 . In the following, we show that a domain wall defect carrying gapless fermions as bounded surface states is experimentally accessible.…”

Section: Resultsmentioning

confidence: 99%

Chiral superfluidity with p-wave symmetry from an interacting s-wave atomic Fermi gas

Liu¹,

Li²,

Wu³

et al. 2014

Nat Commun

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Chiral p-wave superfluids are fascinating topological quantum states of matter that have been found in the liquid 3 He-A phase and arguably in the electronic Sr 2 RuO 4 superconductor. They are fundamentally related to the fractional 5/2 quantum Hall state, which supports fractional exotic excitations. Past studies show that they require spin-triplet pairing of fermions by p-wave interaction. Here we report that a p-wave chiral superfluid state can arise from spin-singlet pairing for an s-wave interacting atomic Fermi gas in an optical lattice. This p-wave state is conceptually distinct from all previous conventional p-wave states as it is for the centre-of-mass motion, instead of the relative motion. It leads to spontaneous generation of angular momentum, finite Chern numbers and topologically protected chiral fermionic zero modes bounded to domain walls, all occuring at a higher critical temperature in relative scales. Signature quantities are predicted for the cold atom experimental condition.

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Section: Resultsmentioning

confidence: 99%

Chiral superfluidity with p-wave symmetry from an interacting s-wave atomic Fermi gas

Liu¹,

Li²,

Wu³

et al. 2014

Nat Commun

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“…For instance, authors in Ref. [43] used a lattice-shaking technique for hybridizing Bloch bands in optical lattices, indeed by shaking a lattice they could introduce a strong effective spin interaction also the organization of large ferromagnetic domains. Hence, our motivation to study this model is introducing new models as double sawtooth spin ladder which can form strong spin interaction of the real materials (lattices of cold [43] and ultracold atoms [44]) created by means of an experimental action such as lattice-shaking.…”

Section: Introductionmentioning

confidence: 99%

“…[43] used a lattice-shaking technique for hybridizing Bloch bands in optical lattices, indeed by shaking a lattice they could introduce a strong effective spin interaction also the organization of large ferromagnetic domains. Hence, our motivation to study this model is introducing new models as double sawtooth spin ladder which can form strong spin interaction of the real materials (lattices of cold [43] and ultracold atoms [44]) created by means of an experimental action such as lattice-shaking. Starting from the nearest-neighbor interstitial Heisenberg dimer coupled legs, we use the cluster expansion technique to calculate the phase transitions and the Gibbs free energy in the parameter spaces, anisotropic Heisenberg XXZ interaction J H (J x ,J z = ∆), J and J ⊥ , and study the influence of the cyclic four-spin exchange on the thermodynamic parameters and spectrum.…”

Section: Introductionmentioning

confidence: 99%

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Phase transitions and thermal entanglement of the distorted Ising–Heisenberg spin chain: topology of multiple-spin exchange interactions in spin ladders

Zad

Ananikian²

2017

J. Phys.: Condens. Matter

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Abstract. We consider a symmetric spin-1/2 Ising-XXZ double sawtooth spin ladder obtained from distorting a spin chain, with the XXZ interaction between the interstitial Heisenberg dimers (which are connected to the spins based on the legs via an Ising-type interaction), the Ising coupling between nearest-neighbor spins of the legs and rungs spins, respectively, and additional cyclic four-spin exchange (ring exchange) in square plaquette of each block. The presented analysis supplemented by results of the exact solution of the model with infinite periodic boundary implies a rich ground state phase diagram. As well as the quantum phase transitions, the characteristics of some of the thermodynamic parameters such as heat capacity, magnetization and magnetic susceptibility are investigated. We here prove that among the considered thermodynamic and thermal parameters, solely the heat capacity is sensitive versus the changes of the cyclic four-spin exchange interaction. By using the heat capacity function, we obtain a singularity relation between the cyclic four-spin exchange interaction and the exchange coupling between pair spins on each rung of the spin ladder. All thermal and thermodynamic quantities under consideration should investigate by regarding those points which satisfy the singularity relation. The thermal entanglement within the Heisenberg spin dimers is investigated by using the concurrence, which is calculated from a relevant reduced density operator in the thermodynamic limit.

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“…Equation (2) describes a shaken optical lattice that has attracted a lot of interest recently in ultracold atom physics [17][18][19][20]. Our scheme therefore works also for shaken optical lattices.…”

mentioning

confidence: 99%

Chirald-Wave Superfluid in Periodically Driven Lattices

2015

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Chiral d-wave superfluid is a preliminary example of topological matters that intrinsically encodes interaction effects. It exhibits fascinating properties including a finite Chern number in the bulk and topologically protected edge states, which have been invoking physicists for decades. However, unlike s-wave superfluids prevalent in nature, its existence requires a strong interaction in the d-wave channel, a criterion that is difficult to access in ordinary systems. So far, such an unconventional superfluid has not been discovered in experiments. Here, we present a new principle for creating a two-dimensional chiral d-wave superfluid using periodically driven lattices. Due to an imprinted two-dimensional pseudospin-orbit coupling, where the sublattice index serves as the pseudospin, s-wave interaction between two hyperfine spin states naturally creates a chiral d-wave superfluid. This scheme also allows physicists to study the phase transition between the topologically distinct s-and d-wave superfluids by controlling the driving field or the particle density.Superfluidity takes center stage in modern condensed matter physics [1,2]. Whereas a large number of elements on the periodic table become superfluids or superconductors at low temperatures, most of them are conventional s-wave ones. Though superfluidity could also occur in high-partial-wave channels, such as p-wave superfluids in Helium and d-wave superconductors in cuprates [3,4], it is very rare that a high-partial-wave superfluidity is accompanied by the time-reversal symmetry breaking. Such chiral superfluids, for instance, the p x + ip y and d x 2 −y 2 + id xy superfluids [5][6][7][8][9][10], give rise to exotic phenomena in an interacting many-body system. It has been realized that one need go beyond the conventional symmetry breaking paradigm to describe these chiral superfluids, since they are distinguished from their counterparts that respect the time-reversal symmetry, such as p x and d x 2 −y 2 , by a finite Chern number, a topological property in the bulk, and chiral edge states protected by topology in a finite system. There have been experimental evidences for the p x + ip y superconductor, which exhibits a Chern number C = 1, to exist in Sr 2 RuO 4 [11]. For the chiral d x 2 −y 2 + id xy superfluid with a Chern number C = 2, there has been no experimental observation yet.To realize a chiral d x 2 −y 2 + id xy superfluid, theoretical studies have proposed using doped graphene for enhancing the d-wave interaction [12], or magnetic impurities for mixing d xy with d x 2 −y 2 in cuprates [9,13]. These proposals requiring sophisticated doping of solid materials have not been realized in experiments so far. In ultracold atoms, though the interaction can be tuned by Feshbach resonance, the strong atom loss near high-partial-wave resonance makes it challenging to explore chiral superfluids with a large d-wave scattering length [14,15]. Here, we propose a new scheme that simply requires s-wave interaction. The idea is to engineer a special band stru...

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Direct observation of effective ferromagnetic domains of cold atoms in a shaken optical lattice

Abstract: 1 arXiv:1305.5487v1 [cond-mat.quant-gas] 1 arXiv:1305.5487v1 [cond-mat.quant-gas]

Cited by 244 publications

References 29 publications

Chiral superfluidity with p-wave symmetry from an interacting s-wave atomic Fermi gas

Chiral superfluidity with p-wave symmetry from an interacting s-wave atomic Fermi gas

Phase transitions and thermal entanglement of the distorted Ising–Heisenberg spin chain: topology of multiple-spin exchange interactions in spin ladders

Chirald-Wave Superfluid in Periodically Driven Lattices

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