Phys.org April 27, 2022 Most theoretical derivations of fundamental radiative processes rely on energetic considerations and detailed balance equations, but not on momentum considerations. An international team of researchers (USA – Harvard University, University of Pennsylvania, Belgium, Spain, Denmark) re-examined the foundations of quantum physics from the perspective of momentum and explored what happens when the momentum of light is reduced to zero. They theoretically demonstrated that momentum recoil, transfer momentum from the field to the atom and Doppler shift are inhibited in NZI materials. Fundamental radiative processes inhibition is also explained due to those momentum considerations inside three-dimensional NZI […]
Tag Archives: Light-matter interaction
Ultrafast control of quantum materials
Phys.org October 18, 2021 An international team of researchers (USA – Brown University, University of Pennsylvania, Germany, Switzerland) reviews recent progress in utilizing ultrafast light-matter interaction to control the macroscopic properties of quantum materials. Particular emphasis is placed on photoinduced phenomena that do not result from ultrafast heating effects but rather emerge from microscopic processes that are inherently nonthermal in nature. Many of these processes can be described as transient modifications to the free energy landscape resulting from the redistribution of quasiparticle populations, the dynamical modification of coupling strengths, and the resonant driving of the crystal lattice. Other pathways result […]
Looking at optical Fano resonances under a new light
Phys.org March 19, 2021 Fano resonances are conventionally understood as sharp spectral features that can be excited only by plane waves with specific frequencies and incident angles. Researchers at the City University of New York proved that they can be tailored to resonate only when excited by a frequency, polarization, and wavefront of choice. This generalization reveals that Fano systems are characterized by eigenwaves that scatter to their time-reversed image upon reflection. They showed that the selected wavefront is locally retroreflected everywhere across the device. These results show that conventional Fano resonances are a subset of a broader dichroic phenomenon […]
Intriguing particles emerge when two photons couple
EurekAlert March 2, 2021 An international team of researchers (UK, Russia) has reported a way to create quasiparticles that bind together two differently coloured particles of light. They have named these formations photon-photon polaritons. They tuned a laser to the specific resonance frequency where a photon is expected to be absorbed, yet no resonance absorption happened. Instead, the photon-photon interaction made up two new resonance frequencies away from the old one. The microresonator provided a whole set of split resonances, where each photon-photon pair displayed its own momentum and energy, allowing the researchers to apply the quasiparticle concept and calculate […]
Nanofibers for quantum technologies at room temperature
Nanowerk February 18, 2021 The faithful mapping of information between matter and light can facilitate communication between distant quantum processing nodes. Strong interaction benefits from tightly confined light fields, as well as from many atoms interacting simultaneously with such fields. An international team of researchers (Austria, Germany Israel) realized efficient light-matter interface by gradually thinning an optical fiber down to a diameter of 200 nm, about 600 times narrower than its original width, and about a quarter of the optical wavelength guided by the fiber. Reaching these dimensions resulted in a unique optical field with more than 99% of the […]
Researchers report quantum-limit-approaching chemical sensing chip
Phys.org January 11, 2021 To fabricate high‐density random metallic nanopatterns with accurately controlled nanogaps an international team of researchers (USA – SUNY Buffalo, China, Saudi Arabia) used four molecules (BZT, 4-MBA, BPT, and TPT), each with different lengths. They used atomic layer deposition and self-assembled monolayers instead of electron-beam lithography. The resulting SERS (surface-enhanced Raman spectroscopy) chip with unprecedented uniformity is relatively inexpensive to produce and has gap size approaching the quantum regime of ≈0.78 nm. They demonstrated its potential for quantitative sensing with the relative standard deviation of 4.3% over large area. All chemicals have unique light-scattering signatures; therefore, […]
Pearls may provide new information processing options for biomedical, military innovations
Science Daily November 13, 2020 To overcome the hardware limitations of conventional spectrometers and hyperspectral imagers a team of researchers in the US (Purdue University, AFRL) has developed a spectral information processing scheme in which light transport through an Anderson-localized medium serves as an entropy source for compressive sampling directly in the frequency domain. As implied by the “lustrous” reflection originating from the exquisite multilayered nanostructures, a pearl (or mother-of-pearl) allows us to exploit the spatial and spectral intensity fluctuations originating from strong light localization for extracting salient spectral information with a compact and thin form factor. The research can […]
Engineers manipulate color on the nanoscale, making it disappear
Nanowerk August 13, 2020 An international team of researchers (USA – University of Pennsylvania, Industry, UCLA, Singapore) demonstrated that nanostructured, multilayer transition metal dichalcogenides (TMDCs) by themselves provide an ideal platform for excitation and control of excitonic modes, paving the way to exciton-photonics. Inherently strong TMDC exciton absorption resonances may be completely suppressed due to excitation of hybrid light-matter states and their interference. The work paves the way to the next generation of integrated exciton optoelectronic nano-devices and applications in light generation, computing, and sensing…read more. Open Access TECHNICAL ARTICLE
New way to control the phase of light using 2D materials
Science Daily February 24, 2020 Little is known about the effect of doping on the optical properties of TMDs at wavelengths far from excitonic resonances, where the material is transparent and therefore could be leveraged in photonic circuits. A team of researchers in the US (Columbia University, North Carolina State University, University of Chicago) has demonstrated the strong electro refractive response of monolayer tungsten disulfide (WS2) at near-infrared wavelengths (deep in the transparency regime) by integrating it on silicon nitride photonic structures to enhance the light–matter interaction with the monolayer. They showed that the doping-induced phase change relative to change […]
How to take a picture of a light pulse
Phys.org January 27, 2020 Measuring the shape of the laser light wave with high accuracy required for investigating materials to medical diagnostics requires a large, complex experimental setup. In their experiment an international team of researchers (Germany, Austria) hit a tiny crystal of silicon oxide with the laser pulse to be investigated. While this laser pulse penetrates the crystal, another strong infrared pulse is fired at the target changing the energy state of the electrons so that they become mobile. As soon as the electrons can move through the crystal, they are accelerated by the electric field of the first […]