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The Maxwell-Bloch equations (MBE) describe the interaction between a two-level quantum mechanical system and an electromagnetic wave. They are widely used in nonlinear optics in general and to model quantum cascade lasers (QCLs) in particular [1]. Due to their nonlinearity, numerical methods are usually required to solve the equations. In order to cope with the computational complexity that arises,...
The recent intense research in the newly founded area of PT-symmetric optics [1,2] has triggered a lot of attention in theoretical and experimental studies of non-Hermitian effects in photonics. In this context of composite photonic systems that contain gain and loss, we recently demonstrated for the first time the existence of so-called “constant-intensity waves” (or CI-waves) [3], which, in the...
The discovery of intersubband transitions in III-V semiconductor heterostructures [I] had a huge impact on large parts of the condensed matter physics community and ultimately led to the development of quantum well infrared photodetectors [2] and quantum cascade lasers [3]. One of the main constraints, however, are the strict lattice matching conditions of the heterostructures — limiting the available...
Two-dimensional van der Waals materials are two-dimensional crystals with strong covalent in-plane bonds and weak van der Waals interaction between the layers with a variety of different electronic, optical and mechanical properties. A very prominent class of two-dimensional materials are transition metal dichalcogenides and amongst them particularly the semiconducting subclass. Their properties include...
We study [1] the application potential of CdSe nanoplatelets (NPLs) [2], a model system for colloidal 2D materials, as field-controlled emitters and their properties. We show that their luminescence emission can be modulated by 28% upon application of electrical fields up to 175 kV/cm. This is a very high modulation depth for field-controlled nanoemitters. Based on our experimental results we estimate...
Variation of the sign of dispersion in air in the vicinity of 3.6 pm [1] makes propagation and filamentation of mid-IR pulses extremely sensitive to the chirp, which allows to take control over the temporal pulse splitting, spectral broadening, energy losses and spatial profile. Here we report on filamentation of 30-mJ, 3.9-pm pulses produced by a hybrid OPA/OPCPA system [2]. Filamentation in ambient...
Bessel beams exploit conical energy flow to yield near-uniform intensity along a line focus which has been shown to be extremely attractive for laser processing in dielectrics. At high power, however, the nonlinear Kerr effect is known to induce significant oscillations of the on-axis intensity which is deleterious for machining applications. Here, we show through theory and numerical modelling how...
We present the numerical demonstration of an harmonically mode-locked multi-similariton laser supporting a low jitter, stable train of self similar high repetition rate pulses exploiting, as mode-locking mechanism, the principle of dissipative Faraday instability (DFI) induced by zigzag modulation of spectral losses [1, 2]. At variance with the theoretical and experimental studies on the DFI [1, 2],...
The realization of integrated light sources capable of emitting non-classical multi-photon states, is a fascinating, yet equally challenging task at the heart of quantum optics [1]. One example of such light-states are photon twins, which up till now have mostly been generated with low emission rates using probabilistic parametric down-conversion sources [2] or atoms [3].
A remarkable progress has recently been achieved in studies of thermodynamics and heat machines, with experiments probing down to micro and nano-scale systems such as the single Brownian particle [1], as well as the single atom [2]. However, despite several theoretical proposals [3, 4], implementation of heat machines in the fully quantum regime remains a challenge. We report on an experimental realization...
A key requirement for implementing photonic quantum information networks is the mutual two-photon interference between photons emitted by spatially separated quantum light sources. In order to up-scale such networks, the deterministic fabrication of efficient sources of single and indistinguishable photons is of crucial importance. So far, few experiments reported on two-photon interference (TPI)...
Optical microtraps provide a strong spatial confinement for laser-cooled atoms. They can, e.g., be realized with strongly focused trapping light beams or the optical near fields of nano-scale waveguides and photonic nanostructures. Atoms in such traps often experience strongly spatially varying AC Stark shifts which are proportional to the magnetic quantum number of the respective energy level. These...
Reversible light-matter interfaces are crucial elements in quantum optics and quantum information networks. In particular, the coupling of one-dimensional bosonic nanoscale waveguides and cold atoms appears as a promising pathway to build strong light-matter interaction thanks to the tight transverse confinement of light.
Semiconductor quantum dots have recently emerged as a leading platform to efficiently generate highly indistinguishable photons [1-3], and this work addresses the timely question of how good these solid-state sources can ultimately be. Based on a microscopic theory, we establish the crucial impact that lattice relaxation has in these systems, which gives rise to a broad phonon sideband in bulk quantum...
Recent advances in cavity quantum optomechanics have enabled breakthroughs such as ground state cooling of mechanical motion, observation of quantum backaction, standard quantum limit of position measurement and entanglement between optical and mechanical degrees of freedom [1]. Simultaneously, the upgraded version of current gravitational-wave interferometers is expected to suffer from optomechanical...
Optical frequency combs in space bear the prospect of dramatically improving satellite navigation and they may pave the pathway for various space applications like satellite formation flights, global satellite navigation, earth observation, and satellite-based fundamental tests of physical constants [1]. Here we report on a precision ranging system based on a dual-comb architecture aiming for fast...
One efficient approach for generating single photons is based on using a two-level atom, which inherently cannot emit more than one photon at the time. As early as the 1980s, this quantum feature was identified as the gateway to creating single photon sources (SPS's), where a regular excitation sequence would produce a stream of photons with photon number fluctuations below the shot noise. Such an...
We are applying our recently developed optical fiber tip nano-tweezers for trapping of luminescent NaYF4:(Er, Yb, Gd) nanorods. The rods were prepared by a solvothermal route based on the reaction between metal and fluoride salts in a mixture of ethanol, water and oleic acid. By controlling the Gadolinium amount it was possible to elaboration rods with very different aspect ratios in the order of...
Efficiently transducing microwave signals into optical signals is one of the major demands in modem telecommunication. Electro-optical crystals hosting optical whispering gallery modes incorporated in a properly designed microwave cavity emerge as a promising candidate towards much more efficient microwave-to-light transducer [1, 2]. Here, we propose to use a ferroelectric crystal close to its paraelectric-ferroelectric...
It is well-known that the spontaneous emission of an excited fluorophore (donor) can be strongly modified by energy transfer (ET), resulting in a decrease of its photoluminescence (PL). Different interaction mechanisms are involved in resonant ET. In particular, resonant ET based on long range dipole-dipole interactions is referred to as Förster Resonant Energy Transfer (FRET) [1]. Radiative Energy...
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