Phys.org August 19, 2024 Researchers in Singapore have showed that the efficiency of spontaneous parametric down-conversion (SPDC) could be improved by harnessing many-body excitonic interactions present in the non-linear optical crystal. They showed that excitonic resonances and interexciton transitions could enhance the probability of SPDC. They benchmarked their ab initio many-body calculations using experimental polar plots of second harmonic generation in NbOI2, demonstrating the relevance of excitons in the nonlinear response. A strong double-exciton resonance in 2D NbOCl2 led to significant enhancement in the second order susceptibility. According to the researchers their work paves the way for the realization of […]
Tag Archives: Entangled photons
Quantum entangled photons react to Earth’s spin
Phys.org June 14, 2024 Optical quantum interferometers are of particular interest because of mature methods for generating and manipulating quantum states of light. Their increased sensitivity promises to enable tests of quantum phenomena. However, this requires long and decoherence-free processing of quantum entanglement, which, for large interferometric areas, remains unexplored territory. Researchers in Austria developed a table-top experiment using maximally path-entangled quantum states of light in a large-scale interferometer sensitive enough to measure the rotation rate of Earth with high sensitivity. According to the researchers further improvements to their methodology will enable tests for fundamental physics allowing the exploration of […]
Through the quantum looking glass
Science Daily September 12, 2022 Quantum state engineering mainly relies on spontaneous parametric downconversion and four-wave mixing, where one or two pump photons spontaneously decay into a photon pair. Both nonlinear effects require momentum conservation for the participating photons, which strongly limits the versatility of the resulting quantum states. Nonlinear metasurfaces have subwavelength thickness and allow the relaxation of this constraint; when combined with resonances, they greatly expand the possibilities of quantum state engineering. An international team of researchers (Germany, USA -Sandia National Laboratory) generated entangled photons via spontaneous parametric downconversion in semiconductor metasurfaces with high–quality factor, quasi-bound state in […]
To capture single photons, researchers create an interference ‘wall’
Phys.org December 3, 2021 Creating entangled photons can be a difficult task requiring a complicated setup as non-classical kinds of light have a small number of photons. In a new scheme researchers at the University of Chicago used two different sources to simultaneously emit photons into a cavity that has an extremely weak nonlinearity. With careful tuning, these sources then cancel each other out with destructive interference—creating a “wall” that blocks photons—once the selected number of photons are captured in the cavity. The basic mechanism can also be applied to all electromagnetic radiation. It can be used to generate and […]