阿秒脉冲的量子光学概念：attoquants
A quantum optical concept of attosecond pulses: the attoquants
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中文总结 AI 辅助
该研究提出新型多模量子态attoquants，可在无需锁模的情况下通过HHG产生阿秒脉冲序列，其为非经典纠缠态，由多原子效应在HHG中生成。
中文摘要 AI 辅助
高次谐波产生（HHG）通常按照经典锁模理论，仅在发射的谐波相互锁相时才被认为能产生阿秒脉冲序列。当谐波场处于可分离的多模量子态时，这种锁相对脉冲合成是必要的。然而，对于表现出模间纠缠的谐波梳，这一要求可完全规避。我们引入一类新型多模量子态，命名为attoquants：这类态与高度结构化的脉冲序列相关，且对相对相位具有固有不敏感性。作为具体示例，我们分析相干永久态，该态由固定参数集所有排列下的相干态乘积的完全对称叠加构成。分析表明，其电场期望值是驱动场谐波的锁相傅里叶叠加，无需锁模即可产生阿秒脉冲序列。我们进一步计算该态的光子统计、维格纳函数及对数负性，确认其为真正的非经典态且存在纠缠。最后，我们对HHG过程中此类纠缠态的产生给出唯象解释，认为这是多原子效应的结果。由于驱动场的相干体积远大于其谐波的相干体积，集体驱动的原子簇可将各谐波辐射为空间分辨但本质不可区分的源，这能生成attoquant的排列对称纠缠结构。
英文摘要
High-harmonic generation (HHG) is conventionally understood to produce attosecond pulse trains only when the emitted harmonics are mutually phase-locked, in accordance with the classical theory of mode-locking. Such locking is necessary for pulse synthesis when the harmonic field is in a separable multimode quantum state. This requirement, however, can be circumvented entirely for harmonic combs exhibiting intermodal entanglement. We introduce a novel family of multimode quantum states, termed attoquants: states associated with highly structured pulse trains that are inherently insensitive to relative phases. As a concrete example, we analyse the coherent permanent state, constructed as a completely symmetric superposition of products of coherent states over all permutations of a fixed parameter set. It is shown analytically that its electric-field expectation value is a locked Fourier superposition of the driving-field harmonics, yielding an attosecond pulse train without requiring mode-locking. We further calculate the photon statistics, the Wigner function, and the logarithmic negativity of this state, confirming it to be genuinely nonclassical and entangled. Finally, we offer a phenomenological interpretation for the generation of such entangled states during HHG, as a consequence of multi-atom effects. Since the coherence volume of the driving field greatly exceeds that of its harmonics, a collectively-driven cluster of atoms can radiate the individual harmonics as spatially resolved, but fundamentally indistinguishable sources. This can generate the permutation-symmetric entanglement structure of an attoquant.
发表机构
- ELI ALPS, The Extreme Light Infrastructure ERIC（极端光基础设施欧洲研究联盟）
- HUN-REN Wigner Research Centre for Physics（匈牙利科学院维格纳物理研究所）
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