Metasurfaces are highly effective at manipulating classical light in the linear regime; however, effectively controlling the polarization of nonclassical light generated from nonlinear resonant metasurfaces remains a challenge. Here, we present a solution by achieving polarization engineering of frequency-nondegenerate biphotons emitted via spontaneous parametric down-conversion in GaAs metasurfaces, utilizing quasi-bound states in the continuum (qBIC) resonances to enhance biphoton generation. Through comprehensive polarization tomography, we demonstrate that the emitted photons’ polarization directly reflects the qBIC mode’s far-field properties. Furthermore, we show that both the type of qBIC mode and the symmetry of the meta-atoms can be tailored to control each single-photon polarization state, and that the subsequent two-photon polarization states are nearly separable, offering potential applications in the heralded generation of single photons with adjustable polarization. This work provides a significant step toward utilizing metasurfaces to generate quantum light and engineer their polarization, a critical aspect for future quantum technologies.
High-harmonic generation by a bright squeezed vacuum
Andrei Rasputnyi,
Zhaopin Chen,
Michael Birk,
Oren Cohen,
Ido Kaminer,
Michael Krüger,
Denis Seletskiy,
Maria Chekhova,
Francesco Tani
Nature Physics
20
1960-1965
(2024)
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High-harmonic generation has been driving the development of attosecond science and sources. More recently, high-harmonic generation in solids has been adopted by other communities as a method to study material properties. However, so far high-harmonic generation has only been driven by classical light, despite theoretical proposals to do so with quantum states of light. Here we observe non-perturbative high-harmonic generation in solids driven by a macroscopic quantum state of light, a bright squeezed vacuum, which we generate in a single spatiotemporal mode. The process driven by a bright squeezed vacuum is considerably more efficient in the generation of high harmonics than classical light of the same mean intensity. Due to its broad photon-number distribution, covering states from 0 to 2 × 10 13 photons per pulse, and strong subcycle electric field fluctuations, a bright squeezed vacuum gives access to free carrier dynamics within a much broader range of peak intensities than accessible with classical light.
Advances in quantum imaging
Hugo Defienne,
Warwick P. Bowen,
Maria Chekhova,
Gabriela Barreto Lemos,
Dan Oron,
Sven Ramelow,
Nicolas Treps,
Daniele Faccio
Modern imaging technologies are widely based on classical principles of light or electromagnetic wave propagation. They can be remarkably sophisticated, with recent successes ranging from single-molecule microscopy to imaging far-distant galaxies. However, new imaging technologies based on quantum principles are gradually emerging. They can either surpass classical approaches or provide novel imaging capabilities that would not otherwise be possible. Here we provide an overview of the most recently developed quantum imaging systems, highlighting the nonclassical properties of sources, such as bright squeezed light, entangled photons and single-photon emitters that enable their functionality. We outline potential upcoming trends and the associated challenges, all driven by a central enquiry, which is to understand whether quantum light can make visible the invisible.
Second-Order Nonlinear Circular Dichroism in Square Lattice Array of Germanium Nanohelices
Grégoire Saerens,
Günter Ellrott,
Olesia Pashina,
Ilya Deriy,
Vojislav Krstić,
Mihail Petrov,
Maria Chekhova,
Rachel Grange
Second-harmonic generation (SHG) is prohibited in centrosymmetric crystals such as silicon or germanium due to the presence of inversion symmetry. However, the structuring of such materials makes it possible to break the inversion symmetry, thus achieving generation of second-harmonic. Moreover, various symmetry properties of the resulting structure, such as chirality, also influence the SHG. In this work, we investigate second-harmonic generation from an array of nanohelices made of germanium. The intensity of the second-harmonic displayed a remarkable enhancement of over 100 times compared to a nonstructured Ge thin film, revealing the influence of interaction between nanohelices. In particular, nonlinear circular dichroism, characterized through the SHG anisotropy factor gSHG–CD, changed its sign not only with the helix handedness but also with its density as well. We believe that our discoveries will open up new paths for the development of nonlinear photonics based on metamaterials and metasurfaces made of centrosymmetric materials.
Fourier-transform infrared spectroscopy with undetected photons from high-gain spontaneous parametric down-conversion
Kazuki Hashimoto,
Dmitri B. Horoshko,
Mikhail I. Kolobov,
Yoad Michael,
Ziv Gefen,
Maria Chekhova
Communications Physics
7
217
(2024)
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Fourier-transform infrared spectroscopy (FTIR) is an indispensable analytical method that allows label-free identification of substances via fundamental molecular vibrations. However, traditional FTIR spectrometers require mid-infrared (MIR) elements, including low-efficiency MIR photodetectors. SU(1,1) interferometry has previously enabled FTIR with undetected MIR photons via spontaneous parametric down-conversion in the low-parametric-gain regime, where the number of photons per mode is much less than one and sensitive photodetectors are needed. In this work, we develop a high-parametric-gain SU(1,1) interferometer for MIR-range FTIR with undetected photons. Using our method, we demonstrate three major advantages: a high photon number at the interferometer output, a considerably lower photon number at the sample, and improved interference contrast. In addition, we broaden the spectral range of the interferometer by aperiodic poling in the gain medium. Exploiting the broadband SU(1,1) interferometer, we measure and evaluate the MIR absorption spectra of polymers in the 3-μm region.
Roadmap on photonic metasurfaces
Sebastian A. Schulz,
Rupert. F. Oulton,
Mitchell Kenney,
Andrea Alù,
Isabelle Staude,
Ayesheh Bashiri,
Zlata Fedorova,
Radoslaw Kolkowski,
A. Femius Koenderink, et al.
Here we present a roadmap on Photonic metasurfaces. This document consists of a number of perspective articles on different applications, challenge areas or technologies underlying photonic metasurfaces. Each perspective will introduce the topic, present a state of the art as well as give an insight into the future direction of the subfield.
Tunable entangled photon-pair generation in a liquid crystal
Vitaliy Sultanov,
Aljaž Kavčič,
Emmanouil Kokkinakis,
Nerea Sebastián,
Maria Chekhova,
Matjaž Humar
Liquid crystals, with their ability to self-assemble, strong response to an electric field and integrability into complex systems, are key materials in light-beam manipulation1. The recently discovered ferroelectric nematic liquid crystals2,3 also have considerable second-order optical nonlinearity, making them a potential material for nonlinear optics4,5. Their use as sources of quantum light could considerably extend the boundaries of photonic quantum technologies6. However, spontaneous parametric down-conversion, the basic source of entangled photons7, heralded single photons8 and squeezed light9, has so far not been observed in liquid crystals—or in any liquids or organic materials. Here we implement spontaneous parametric down-conversion in a ferroelectric nematic liquid crystal and demonstrate electric-field tunable broadband generation of entangled photons, with an efficiency comparable to that of the best nonlinear crystals. The emission rate and polarization state of photon pairs is markedly varied by applying a few volts or twisting the molecular orientation along the sample. A liquid-crystal source enables a special type of quasi-phase matching10, which is based on the molecular twist structure and is therefore reconfigurable for the desired spectral and polarization properties of photon pairs. Such sources promise to outperform standard nonlinear optical materials in terms of functionality, brightness and the tunability of the generated quantum state. The concepts developed here can be extended to complex topological structures, macroscopic devices and multi-pixel tunable quantum light sources.
Multiphoton electron emission with non-classical light
Jonas Heimerl,
Alexander Mikhaylov,
Stefan Meier,
Henrick Höllerer,
Ido Kaminer,
Maria Chekhova,
Peter Hommelhoff
Photon number distributions of classical and non-classical light sources have been studied extensively, yet their impact on photoemission processes is largely unexplored. In this article, we present measurements of electron number distributions from metal needle tips illuminated with ultrashort light pulses with various photon quantum statistics. By varying the photon statistics of the exciting light field between classical (Poissonian) and quantum (super-Poissonian), we demonstrate that the measured electron distributions are changed substantially. Using single-mode bright squeezed vacuum light, we measure extreme statistics events with up to 65 electrons from one light pulse at a mean of 0.27 electrons per pulse—the likelihood for such an event equals 10−128 with Poissonian statistics. By changing the number of modes of the exciting bright squeezed vacuum, we can tailor the electron number distribution on demand. Most importantly, our results demonstrate that the photon statistics is imprinted from the driving light to the emitted electrons, opening the door to new sensor devices and to strong-field optics with quantum light and electrons.
Quantitative analysis of the intensity distribution of optical rogue waves
Éva Rácz,
Kirill Spasibko,
Mathieu Manceau,
László Ruppert,
Maria Chekhova,
Radim Filip
Communications Physics
7
119
(2024)
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The field of optical rogue waves is a rapidly expanding topic with a focus on explaining their emergence. To complement this research, instead of providing a microscopic model that generates extreme events, we concentrate on a general quantitative description of the observed behavior. We explore two complementary top-down approaches to estimating the exponent describing the power-law decaying distribution of optical rogue waves observed in supercontinuum generated in a single-mode fiber in the normal-dispersion regime by applying a highly fluctuating pump. The two distinct approaches provide consistent results, outperforming the standard Hill estimator. Further analysis of the distributions reveals the breakdown of power-law behavior due to pump depletion and detector saturation. Either of our methods is adaptable to analyze extreme-intensity events from arbitrary experimental data.
Kontakt
Forschungsgruppe Maria Chekhova
Max-Planck-Institut für die Physik des Lichts Staudtstr. 2 91058 Erlangen
