FFLO Superfluids in 2D Spin-Orbit Coupled Fermi Gases

Zheng, Zhen; Gong, Ming; Zhang, Yichao; Zou, Xu‐Bo; Zhang, Chuanwei; Guo, Guang‐Can

doi:10.1038/srep06535

Cited by 32 publications

(37 citation statements)

References 50 publications

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“…Thus the wave function of the Cooper pair can be written as cos(qy)|S + sin(qy)|T , where |S = |↑↓ − |↓↑ and |T = |↑↓ + |↓↑ are the singlet and triplet pairing wave functions, respectively. So, the presence of SOC stabilizes the FFLO phase as the SOC lifts the spin degeneracy and shifts the Fermi surface in such a way that the resulting Cooper pair has a finite center of momentum [96,97].…”

Section: Discussionmentioning

confidence: 99%

Full proximity treatment of topological superconductors in Josephson-junction architectures

Setiawan

Levin

2019

Phys. Rev. B

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Experiments on planar Josephson-junction architectures have recently been shown to provide an alternative way of creating topological superconductors hosting accessible Majorana modes. These zero-energy modes can be found at the ends of a one-dimensional channel in the junction of a twodimensional electron gas (2DEG) proximitized by two spatially separated superconductors. The channel, which is below the break between the superconductors, is not in direct contact with the superconducting leads, so that proximity coupling is expected to be weaker and less well controlled than in the simple nanowire configuration widely discussed in the literature. This provides a strong incentive for this paper which investigates the nature of proximitization in these Josephson junction architectures. At a microscopic level we demonstrate how and when it can lead to topological phases. We do so by going beyond simple tunneling models through solving self-consistently the Bogoliubov-de Gennes equations of a heterostructure multicomponent system involving two spatially separated s-wave superconductors in contact with a normal Rashba spin-orbit-coupled 2DEG. Importantly, within our self-consistent theory we present ways of maximizing the proximity-induced superconducting gap by studying the effect of the Rashba spin-orbit coupling, chemical potential mismatch between the superconductor and 2DEG, and sample geometry on the gap. Finally, we note (as in experiment) a Fulde-Ferrell-Larkin-Ovchinnikov phase is also found to appear in the 2DEG channel, albeit under circumstances which are not ideal for the topological superconducting phase.

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Section: Discussionmentioning

confidence: 99%

Full proximity treatment of topological superconductors in Josephson-junction architectures

Setiawan

Levin

2019

Phys. Rev. B

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“…Based on this minimal and realistic system, several authors have investigated the rich interplay between the Rashba-induced BCS-BEC crossover, the population imbalance produced by the Zeeman term, and the emergence of topological order, which could be observed by varying the control parameters (h z , κ, a s ) [209,[280][281][282]. These simple systems present a new path for exploring the FFLO finite-momentum paired states [283][284][285][286][287]. Finally, we note that finitemomentum ground-states can be generated in Rashba-coupled Fermi gases also in the absence of a Zeeman splitting term, provided that the collisional interaction is strong enough [231].…”

Section: Interacting Fermi Gases With Socmentioning

confidence: 99%

Light-induced gauge fields for ultracold atoms

et al. 2014

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Abstract. Gauge fields are central in our modern understanding of physics at all scales. At the highest energy scales known, the microscopic universe is governed by particles interacting with each other through the exchange of gauge bosons. At the largest length scales, our universe is ruled by gravity, whose gauge structure suggests the existence of a particle -the graviton-that mediates the gravitational force. At the mesoscopic scale, solid-state systems are subjected to gauge fields of different nature: materials can be immersed in external electromagnetic fields, but they can also feature emerging gauge fields in their low-energy description. In this review, we focus on another kind of gauge field: those engineered in systems of ultracold neutral atoms. In these setups, atoms are suitably coupled to laser fields that generate effective gauge potentials in their description. Neutral atoms "feeling" laser-induced gauge potentials can potentially mimic the behavior of an electron gas subjected to a magnetic field, but also, the interaction of elementary particles with non-Abelian gauge fields. Here, we review different realized and proposed techniques for creating gauge potentials -both Abelian and non-Abelian -in atomic systems and discuss their implication in the context of quantum simulation. While most of these setups concern the realization of background and classical gauge potentials, we conclude with more exotic proposals where these synthetic fields might be made dynamical, in view of simulating interacting gauge theories with cold atoms.arXiv:1308.6533v3 [cond-mat.quant-gas]

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“…Consequently the FFLO momentum q was directly reflected in the expansion velocities of the unpaired fermions because in 1D they form a Fermi sea of non-interacting quasiparticles with Fermi momentum k F↑ − k F↓ . The use of time-of-flight expansion for measuring momentum distributions and detecting the FFLO state have also been considered in spin-orbit coupled systems [213,216,268].…”

Section: Ramps and Quenchesmentioning

confidence: 99%

The Fulde–Ferrell–Larkin–Ovchinnikov state for ultracold fermions in lattice and harmonic potentials: a review

et al. 2018

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We review the concepts and the present state of theoretical studies of spin-imbalanced superfluidity, in particular the elusive Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, in the context of ultracold quantum gases. The comprehensive presentation of the theoretical basis for the FFLO state that we provide is useful also for research on the interplay between magnetism and superconductivity in other physical systems. We focus on settings that have been predicted to be favourable for the FFLO state, such as optical lattices in various dimensions and spin-orbit coupled systems. These are also the most likely systems for near-future experimental observation of the FFLO state. Theoretical bounds, such as Bloch's and Luttinger's theorems, and experimentally important limitations, such as finite-size effects and trapping potentials, are considered. In addition, we provide a comprehensive review of the various ideas presented for the observation of the FFLO state. We conclude our review with an analysis of the open questions related to the FFLO state, such as its stability, superfluid density, collective modes and extending the FFLO superfluid concept to new types of lattice systems.

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FFLO Superfluids in 2D Spin-Orbit Coupled Fermi Gases

Cited by 32 publications

References 50 publications

Full proximity treatment of topological superconductors in Josephson-junction architectures

Full proximity treatment of topological superconductors in Josephson-junction architectures

Light-induced gauge fields for ultracold atoms

The Fulde–Ferrell–Larkin–Ovchinnikov state for ultracold fermions in lattice and harmonic potentials: a review

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