When two resonant modes in a system with gain or loss coalesce both their resonance position and width, so-called exceptional point occurs, which acts as source of non-trivial physics diverse range systems. Lasers provide natural setting to study such non-Hermitian degeneracies, they feature material basic constituents. Here we show that points can be conveniently induced photonic molecule laser by suitable variation the applied pump. Using pair coupled microdisk quantum cascade lasers,...

We demonstrate that the above-threshold behavior of a laser can be strongly affected by exceptional points which are induced pumping nonuniformly. At these singularities, eigenstates non-Hermitian operator describes lasing modes coalesce. In their vicinity, may turn off even when overall pump power deposited in system is increased. Such signatures pump-induced point experimentally probed with coupled ridge or microdisk lasers.

Unlike conventional lasers, diffusive random lasers (DRLs) have no resonator to trap light and high-Q resonances support lasing. Because of this lack sharp resonances, the DRL has presented a challenge laser theory. We present theory able treat rigorously provide results on lasing spectra, internal fields, output intensities DRLs. Typically DRLs are highly multimode emitting at number wavelengths. show that modal interactions through gain medium in such extremely strong lead uniformly spaced...

We report on the engineering of a nondispersive (flat) energy band in geometrically frustrated lattice micropillar optical cavities. By taking advantage non-Hermitian nature our system, we achieve bosonic condensation exciton polaritons into flat band. Because infinite effective mass such band, condensate is highly sensitive to disorder and fragments localized modes reflecting elementary eigenstates produced by geometric frustration. This realization offers novel approach studying coherent...

Mediated photon-photon interactions are realized in a superconducting coplanar waveguide cavity coupled to charge qubit. These non-resonant blockade the transmission of photons through cavity. This so-called dispersive photon is characterized by measuring total transmitted power while varying energy spectrum incident on A staircase with four distinct steps observed and can be understood an analogy electron transport Coulomb quantum dots. work differs from previous efforts that cavity-qubit...

We report unidirectional emission from lasing in In0.09Ga0.91N/In0.01Ga0.99N multiple-quantum-well spiral micropillars. Our imaging technique shows that the maximum comes notch of microcavities at an angle about 40° normal notch. At room temperature, microcavity lases near 400 nm when optically pumped with 266 or 355 light. A reduction threshold and improvement unidirectionality occurs is selectively its boundary.

We theoretically investigate the optical response of a one-dimensional array strongly nonlinear microcavities. When nonlinearity is much larger than both losses and intercavity tunnel coupling, nonequilibrium steady state system reminiscent correlated Tonks-Girardeau gas impenetrable bosons. Signatures strong correlations are identified in transmission spectrum system, as well intensity transmitted light. Possible experimental implementations state-of-the-art solid-state devices discussed.

A semiclassical theory of single and multi-mode lasing is derived for open complex or random media using a self-consistent linear response formulation. Unlike standard approaches which use closed cavity solutions to describe the modes, we introduce an appropriate discrete basis functions also intensity angular emission pattern outside cavity. This constant flux (CF) dictated by Green function arises when formulating steady state Maxwell-Bloch equations as problem. similar quasi-bound...

We propose a class of synthetic optical materials in which the refractive index satisfies $n(\ensuremath{-}\mathbit{x})=\ensuremath{-}{n}^{*}(\mathbit{x})$. term such systems antisymmetric parity-time ($\mathcal{APT}$) structures. Unlike $\mathcal{PT}$-symmetric systems, require balanced gain and loss, i.e., $n(\ensuremath{-}\mathbit{x})={n}^{*}(\mathbit{x})$, $\mathcal{APT}$ consist positive- negative-index materials. Despite seemingly potential...

In conventional lasers, the optical cavity that confines photons also determines essential characteristics of lasing modes such as wavelength, emission pattern, directivity, and polarization. random which do not have mirrors or a well-defined cavity, light is confined within gain medium by means multiple scattering. The sharp peaks in spectra semiconductor powders, first observed 1999, has therefore lead to an intense debate about nature these so-called lasers with resonant feedback. We...

Recent experiments on similarly shaped polymer microcavity lasers show a dramatic difference in the far-field emission patterns. We show, for different deformations of ellipse, quadrupole and hexadecapole, that large differences patterns are explained by differing ray dynamics corresponding to each shape. Analyzing appropriate phase space motion, it is shown geometries unstable manifolds periodic orbits decisive factors determining pattern. Surprisingly, we find strongly chaotic compatible...

The study of light-matter interaction has seen a resurgence in recent years, stimulated by highly controllable, precise, and modular experiments cavity quantum electrodynamics (QED). achievement strong coupling, where the coupling between single atom fundamental mode exceeds decay rates, was major milestone that opened doors to multitude new investigations. Here we introduce multimode (MMSC), is comparable free spectral range (FSR) cavity, i.e. rate at which qubit can absorb photon from...

Systems of strongly interacting atoms and photons, that can be realized wiring up individual cavity QED systems into lattices, are perceived as a new platform for quantum simulation. While sharing important properties with other particles here we argue the nature light-matter interaction gives rise to unique features no analogs in condensed matter or atomic physics setups. By discussing lattice model delocalized photons coupled locally two-level through elementary described by Rabi model,...

Bath engineering, which utilizes coupling to lossy modes in a quantum system generate nontrivial steady states, is tantalizing alternative gate- and measurement-based science. Here, we demonstrate dissipative stabilization of entanglement between two superconducting transmon qubits symmetry-selective manner. We utilize the engineered symmetries environment stabilize target Bell state; further suppression state opposite symmetry due parity selection rules. This implementation resource...

We study the coherence and fluorescence properties of coherently pumped dissipative Jaynes-Cummings-Hubbard model describing polaritons in a coupled-cavity array. At weak hopping we find strong signatures photon blockade similar to single-cavity systems. state photons array depends on its size. While persists dimer consisting two coupled cavities, coherent forms an extended lattice, which can be described terms semi-classical model.

Here, we report the experimental observation of a dynamical quantum phase transition in strongly interacting open photonic system. The system studied, comprising Jaynes-Cummings dimer realized on superconducting circuit platform, exhibits dissipation-driven localization transition. Signatures homodyne signal and photon number reveal this to be from regime classical oscillations into macroscopically self-trapped state manifesting revivals, fundamentally phenomenon. This experiment also...

We analyze the nonequilibrium dynamics of a gas interacting photons in an array coupled dissipative nonlinear cavities when driven by pulsed external coherent field. Using mean-field approach, we show that response system is strongly sensitive to underlying (equilibrium) quantum phase transition from Mott insulator superfluid state at commensurate filling. find coherence cavity emission after quench can be used determine diagram optical many-body even presence dissipation.

We discuss a class of lasing modes created by spatially inhomogeneous gain profile. These are "extra modes", in addition to, and very different from, conventional modes, which arise from the passive cavity resonances. new do not have high intensity across entire region, but instead localized at boundary throughout gain-free region. They surface originating transmission resonances Using an S-matrix description we connect these to PT-symmetric (balanced gain-loss) cavities.

We show that photons in two tunnel-coupled microwave resonators each containing a single superconducting qubit undergo sharp nonequilibrium delocalization-localization (self-trapping) transition due to strong photon-qubit coupling. find self-trapping of one the (spatial localization) forces opposite resonator remain its initial state (energetic localization). This allows for an easy experimental observation by local readout state. Dissipation and decoherence favor self-trapped regime.

Recent experiments have demonstrated an open system realization of the Dicke quantum phase transition in motional degrees freedom optically driven Bose–Einstein condensate a cavity. Relevant collective excitations this light–matter are polaritonic nature, allowing access to critical behavior model through light leaking out This opens path using photodetection-based optical techniques study dynamics and elementary system. We first discuss photon flux observed at cavity face find that it...

We study the nonequilibrium steady state of driven-dissipative Bose-Hubbard model with Kerr nonlinearity. Employing a mean-field decoupling for intercavity hopping $J$, we find that steep crossover between low and high photon-density states inherited from single cavity transforms into gas--liquid bistability at large cavity-coupling $J$. formulate van der Waals--like phenomenology this setting determine relevant phase diagrams, including new type diagram where lobe-shaped boundary separates...

We explore the phase diagram of dissipative Rabi-Hubbard model, as could be realized by a Raman-pumping scheme applied to coupled cavity array. There exist various exotic attractors, including ferroelectric, antiferroelectric, and incommensurate fixed points, well regions persistent oscillations. Many these features can understood analytically truncating two lowest lying states Rabi model on each site. also show that survive beyond mean field, using matrix product operator simulations.