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arXiv 2602.09376math-phmath.MP
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具有同心$\\\delta$壳相互作用的Schrödinger算子

Schrödinger operators with concentric $δ$--shell interactions

Tohoku Gakuin University(东北学院大学)

Masahiro Kaminaga

AI总结:

研究三维空间中具有有限个同心球面$\\\delta$壳相互作用的Schrödinger算子,通过边界积分方法得到显式预解式表示,并详细分析两壳情形下的负谱特性。

摘要:

我们研究$\\\mathbb R^3$上具有有限个同心球面$\\\delta$壳相互作用的Schrödinger算子。这些算子通过二次型方法定义,并由穿过每个壳的连续性以及径向导数的通常跳跃条件描述。基于自由Green核和单层势的边界积分方法,我们推导了具有有界耦合强度的任意数量壳的显式预解式表示。这给出了一个具体的Kre\uın型公式和一个边界算子,其不可逆性刻画了离散谱,并且与旋转对称性下的分波约化兼容。然后我们专门研究具有恒定耦合的两壳情形,并得到负谱的详细描述。特别地,我们证明了基态(如果存在)位于$s$波扇区,并推导了束缚态的显式久期方程。对于大的壳间距,每个束缚能级以指数小的修正趋近于相应的单壳能级,而当单壳能级被调谐到重合时,出现真正的隧穿分裂。作为一个简单的校准,我们将两壳参数与代表性的核壳量子点尺度联系起来。在量级和定性趋势上,I型构型产生相对强束缚的态,而II型构型产生相对浅的外壳态。

英文摘要:

We study Schrödinger operators on $\mathbb R^3$ with finitely many concentric spherical $δ$-shell interactions. The operators are defined by the quadratic form method and are described by continuity across each shell together with the usual jump condition for the radial derivative. Using a boundary integral approach based on the free Green kernel and single-layer potentials, we derive an explicit resolvent representation for an arbitrary number of shells with bounded coupling strengths. This yields a concrete Kre\uın-type formula and a boundary operator whose noninvertibility characterizes the discrete spectrum, and it is compatible with a partial-wave reduction under rotational symmetry. We then specialize to the two-shell case with constant couplings and obtain a detailed description of the negative spectrum. In particular, we show that the ground state (when it exists) lies in the $s$-wave sector and derive an explicit secular equation for bound states. For large shell separation, each bound level approaches the corresponding single-shell level with exponentially small corrections, while a genuine tunneling splitting appears when the single-shell levels are tuned to coincide. As a simple calibration, we relate the two-shell parameters to representative core-shell quantum dot scales. At the level of order-of-magnitude and qualitative trends, Type~I configurations yield a relatively strongly confined state, whereas Type~II configurations produce a comparatively shallow outer-shell state.

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