Measurement of Penrose Superradiance in a Photon Superfluid
Measurement of Penrose Superradiance in a Photon Superfluid
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DOI：
10.1103/physrevlett.128.013901
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发表时间：
2022-01-04
影响因子：
8.6
通讯作者：
Faccio, Daniele
中科院分区：
文献类型：
--
作者：
Braidotti, Maria Chiara;Prizia, Radivoje;Faccio, Daniele
50多年前，罗杰·彭罗斯爵士首先阐明了旋转介质散射中的超辐射放大，这是粒子从旋转的黑洞中获得能量的一种方式。尽管这一基本过程在波动物理学中也是普遍存在的，但它只在水箱中被实验观察到一次。在这里，我们测量了在超流状态下的非线性光学实验的放大倍数。特别是，通过将携带轨道角动量的弱光束聚焦到强抽运涡旋光束的核心上，产生负范数模并将其囚禁在涡旋核心内，从而允许反射光束的放大。我们的实验证明了一种新的非线性光学四波混频的放大反射，它的相位关系与我们的光子超流体中彭罗斯超辐射的Zel‘dovich-Misner条件相一致，并揭示了负频率模在这一过程中所起的作用。
The superradiant amplification in the scattering from a rotating medium was first elucidated by Sir Roger Penrose over 50 years ago as a means by which particles could gain energy from rotating black holes. Despite this fundamental process being ubiquitous also in wave physics, it has only been observed once experimentally, in a water tank. Here, we measure this amplification for a nonlinear optics experiment in the superfluid regime. In particular, by focusing a weak optical beam carrying orbital angular momentum onto the core of a strong pump vortex beam, negative norm modes are generated and trapped inside the vortex core, allowing for amplification of a reflected beam. Our experiment demonstrates amplified reflection due to a novel form of nonlinear optical four-wave mixing, whose phase-relation coincides with the Zel'dovich-Misner condition for Penrose superradiance in our photon superfluid, and unveil the role played by negative frequency modes in the process.