I analyze new phenomena arising from embedding active materials inside of photonic crystal structures. These structures strongly modify the photonic local density of states (LDOS), leading to quantitative and qualitative changes in the behavior of active materials. First, I show that the emission spectrum of pointlike sources inside an “omniguide” is strongly modified by features resembling one...

We report on the simultaneous observation of spontaneous symmetry breaking and long-range spatial coherence both in the strong- and the weak-coupling regime in a semiconductor microcavity. Under pulsed excitation, the formation of a stochastic order parameter is observed in polariton and photon lasing regimes. Single-shot measurements of the Stokes vector of the emission exhibit the buildup of ...

The importance of the photon-photon pair production process (γ + γ′ → e+ + e−) to form pair production cascades in pulsar polar caps is investigated within the framework of the Ruderman-Sutherland vacuum gap model. It is found that this process is unimportant if the polar caps are not hot enough, but will play a non-negligible role in the pair formation cascades when the polar cap temperatures ...

For the applications in quantum information and experiments on the foundations of quantum mechanics a robust narrow-band single photon source is desirable. We report on single photon emission from the Silicon Vacancy (SiV) centers in diamond fabricated by ion implantation. Single SiV centers are photostable and have a spectrum consisting of a sharp zero phonon line (FWHM is about 5 nm) at 738 n...

Two-photon emission is a process in which electron transition between quantum levels occurs through the simultaneous emission of two photons. This phenomenon is important for astrophysics and atomic physics, and semiconductor twophoton emission was recently proposed as a compact source of entangled photons, essential for practical quantum information processing, and three orders of magnitude mo...

Photon-induced interactions have traditionally been studied with lepton beams in fixed target experiments and at colliders. But two–photon and photon–hadron interactions can occur also when the lepton beams are replaced by high energy protons or heavy ions[1,2]. The electromagnetic interactions can be studied in ultra-peripheral collisions where the impact parameters are larger than the sum of ...

Two-photon interactions of entangled-photon pairs with metallic nanoparticles (NPs) can be enhanced by localized surface-plasmon resonance. Recently, we have described how the properties this quantum light-matter interaction deduced from classical second-harmonic generation measurements performed using a reference-free hyper-Rayleigh scattering method. Herein, report results such classical-ligh...

A bstract We use Swampland principles to theoretically disfavor regions of the parameter space dark matter and other darkly charged particles that may exist. The Festina Lente bound, analogue Weak-Gravity conjecture in de Sitter, places constraints on mass charge particles, which here we show cover are currently allowed by observations. As a consequence, broad set new ultra-light Swampland, ind...

Resonant excitation is an essential tool in the development of semiconductor quantum dots (QDs) for information processing. One central challenge to enable transparent access QD signal without post-selection loss. A viable path through cavity enhancement, which has successfully lifted resonantly scattered field strength over laser background under weak excitation. Here, we extend this success s...

This paper deals with so-called Ultra-Peripheral Collisions (UPCs) of heavy ions[ 1, 2]. These can be defined as collisions in which no hadronic interactions occur because of the large spatial separation between the projectile and target. The interactions are instead mediated by the electromagnetic field. Two types of ultra-peripheral collisions can be distinguished: purely electro-magnetic int...