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中国物理学会期刊

非厄米耗散对超流态的双重调控机制:促进BCS与抑制有限动量

Dual Regulation Mechanism of Non-Hermitian Dissipation on Superfluid States: Promoting BCS and Suppressing Finite-Momentum Pairing

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  • 非厄米量子多体物理是当前物理学的前沿热点,其中冷原子体系为探索非厄米多体效应提供了理想的实验平台。本文基于非厄米平均场理论,研究了具有单体耗散的二维自旋-轨道耦合费米气体,系统分析了质心动量为零(BCS态)与非零(有限动量态)条件下的超流特性。研究发现,单体耗散对超流态具有显著的双重调控作用:一方面,它能有效促进常规的BCS超流,表现为序参量增大及能量差降低;另一方面,它显著抑制了有限动量超流态的形成。进一步分析表明,这种抑制效应源于非厄米耗散破坏了由实塞曼场诱导的费米面不对称性,从而驱动系统趋向于对称的BCS超流态。本工作揭示了非厄米耗散在超流调控中的关键作用,为理解开放量子多体系统中的新奇物理提供了新视角。

     

    Non-Hermitian quantum many-body physics has emerged as a frontier at the intersection of condensed matter and ultracold atom research, with cold atomic gases providing a highly tunable platform for probing exotic non-Hermitian manybody effects. Motivated by these advances, we investigate a two-dimensional swave interacting Fermi gas subjected to both spin-orbit coupling (SOC) and engineered single-particle dissipation. Employing a non-Hermitian mean-field framework, we systematically explore the superfluid ground-state properties across two distinct pairing channels: the conventional BCS state with zero center-of-mass momentum and the finite-momentum FFLO-type state. Our results reveal a remarkable dual regulatory role of dissipation: it enhances conventional BCS superfluidity—manifested by a pronounced increase in the pairing order parameter and a concomitant reduction in the energy difference between the superfluid and normal states—while concurrently suppressing finite-momentum superfluid ordering. Mechanistically, the enhancement is attributed to a reduced singleparticle energy gap and a dissipation-induced increase in the Fermi-level density of states, both of which facilitate more effcient Cooper pairing. In contrast, the suppression of finite-momentum superfluidity originates from the dissipationdriven destruction of Fermi surface asymmetry, which is initially established by the real Zeeman field; this disruption effectively eliminates the momentum-space imbalance essential for finite-momentum pairing, steering the system toward a symmetric BCS ground state. Our findings establish non-Hermitian dissipation as a powerful tuning knob for superfluid manipulation and offer experimentally testable predictions for exploring emergent physics in open quantum many-body systems.

     

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