## About

45

Publications

8,776

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625

Citations

Introduction

Additional affiliations

July 2018 - September 2020

July 2017 - September 2017

October 2013 - present

Education

October 2013 - September 2017

January 2012 - June 2013

October 2008 - January 2012

## Publications

Publications (45)

Superfluidity, first discovered in liquid ⁴He, is closely related to Bose–Einstein condensation (BEC) phenomenon. However, even at zero temperature, a fraction of the quantum liquid is excited out of the condensate into higher momentum states via interaction-induced fluctuations—the phenomenon of quantum depletion. Quantum depletion of atomic BECs...

We demonstrate an experimental approach for creating spatially localized states in a semiconductor microcavity laser. In particular, we shape the spatial gain profile of a quasi-one-dimensional microcavity laser with a nonresonant, pulsed optical pump to create spatially localized structures, known as gain-pinned dissipative solitons, that exist du...

Topological insulators are a class of electronic materials exhibiting robust edge states immune to perturbations and disorder. This concept has been successfully adapted in photonics, where topologically nontrivial waveguides and topological lasers were developed. However, the exploration of topological properties in a given photonic system is limi...

We report the observation of low-energy, low-momenta collective oscillations of an exciton-polariton condensate in a round “box” trap. The oscillations are dominated by the dipole and breathing modes, and the ratio of the frequencies of the two modes is consistent with that of a weakly interacting two-dimensional trapped Bose gas. The speed of soun...

Many bosons can occupy a single quantum state without a limit. It is described by the quantum-mechanical Bose–Einstein statistic, which allows Bose–Einstein condensation at low temperatures and high particle densities. Photons, historically the first considered bosonic gas, were late to show this phenomenon, observed in rhodamine-filled microcaviti...

The emergence of spatial coherence in a confined two-dimensional Bose gas of exciton-polaritons with tuneable interactions offers a unique opportunity to explore the role of interactions in a phase transition in a driven-dissipative quantum system, where both the phase transition and thermalisation are mediated by interactions. We investigate, expe...

Exciton-polariton lasers are a promising source of coherent light for low-energy applications due to their low-threshold operation. However, a detailed experimental study of their spectral purity, which directly affects their coherence properties, is still missing. Here, we present a high-resolution spectroscopic investigation of the energy and lin...

Many bosons can occupy a single quantum state without a limit. This state is described by quantum-mechanical Bose-Einstein statistics, which allows the formation of a Bose-Einstein condensate at low temperatures and high particle densities. Photons, historically the first considered bosonic gas, were late to show this phenomenon, which was observed...

The classic Bogoliubov theory of weakly interacting Bose gases rests upon the assumption that nearly all the bosons condense into the lowest quantum state at sufficiently low temperatures. Here we develop a generalized version of Bogoliubov theory for the case of a driven-dissipative exciton-polariton condensate with a large incoherent uncondensed...

Optical trapping has been proven to be an effective method of separating exciton-polariton condensates from the incoherent high-energy excitonic reservoir located at the pumping laser position. This technique has significantly improved the coherent properties of exciton-polariton condensates, when compared to a quasi-homogeneous spot excitation sch...

Optical trapping has been proven to be an effective method of separating exciton-polariton condensates from the incoherent high-energy excitonic reservoir located at the pumping laser position. This technique has significantly improved the coherent properties of exciton-polariton condensates, when compared to a quasi-homogeneous spot excitation sch...

The classic Bogoliubov theory of weakly interacting Bose gases rests upon the assumption that nearly all the bosons condense into the lowest quantum state at sufficiently low temperatures. Here we develop a generalized version of Bogoliubov theory for the case of a driven-dissipative exciton-polariton condensate with a large incoherent uncondensed...

Topology is central to understanding and engineering materials that display robust physical phenomena immune to imperfections. Different topological phases of matter are characterized by topological invariants. In energy-conserving (Hermitian) systems, these invariants are determined by the winding of eigenstates in momentum space. In non-Hermitian...

Collective (elementary) excitations of quantum bosonic condensates, including condensates of exciton polaritons in semiconductor microcavities, are a sensitive probe of interparticle interactions. In anisotropic microcavities with momentum-dependent transverse-electric–transverse-magnetic splitting of the optical modes, the excitations’ dispersions...

We investigate the effects of direct deposition of different dielectric materials (AlOx, SiOx, SiNx) onto atomically thin TMDC WS2 on its optical response using atomic layer deposition (ALD), electron beam evaporation (EBE), plasma-enhanced chemical vapor deposition (PECVD), and magnetron sputtering. The photoluminescence measurements reveal quench...

Monolayer transition metal dichalcogenide crystals (TMDCs) hold great promise for semiconductor optoelectronics because their bound electron-hole pairs (excitons) are stable at room temperature and interact strongly with light. When TMDCs are embedded in an optical microcavity, excitons can hybridise with cavity photons to form exciton polaritons,...

Topological insulators are a class of electronic materials exhibiting robust edge states immune to perturbations and disorder. This concept has been successfully adapted in photonics, where topologically nontrivial waveguides and topological lasers were developed. However, the exploration of topological properties in a given photonic system is limi...

The integration of two-dimensional transition metal dichalcogenide crystals (TMDCs) into a dielectric environment is critical for optoelectronic and photonic device applications. Here, we investigate the effects of direct deposition of different dielectric materials (Al$_2$O$_3$, SiO$_2$, SiN$_x$) onto atomically thin (monolayer) TMDC WS$_2$ on its...

Atomically-thin transition metal dichalcogenide crystals (TMDCs) hold great promise for future semiconductor optoelectronics due to their unique electronic and optical properties. In particular, electron-hole pairs (excitons) in TMDCs are stable at room temperature and interact strongly with light. When TMDCs are embedded in an optical microcavity,...

Topology is central to understanding and engineering materials that display robust physical phenomena immune to imperfections. The topological character of a material is quantified by topological invariants that simplify the classification of topological phases. In energy-conserving systems, the topological invariants, e.g., the Chern number, are d...

Atomically thin transition metal dichalcogenide crystals (TMDCs) have extraordinary optical properties that make them attractive for future optoelectronic applications. Integration of TMDCs into practical all‐dielectric heterostructures hinges on the ability to passivate and protect them against necessary fabrication steps on large scales. Despite...

Collective (elementary) excitations of quantum bosonic condensates, including condensates of exciton polaritons in semiconductor microcavities, are a sensitive probe of interparticle interactions. In anisotropic microcavities with momentum-dependent TE-TM splitting of the optical modes, the excitations dispersions are predicted to be strongly aniso...

Monolayer transition metal dichalcogenides are a promising platform to investigate many-body interactions of excitonic complexes. In monolayer tungsten diselenide, the ground-state exciton is dark (spin-indirect), and the valley degeneracy allows low-energy dark momentum-indirect excitons to form. Interactions between the dark exciton species and t...

Atomically thin transition metal dichalcogenide crystals (TMDCs) have extraordinary optical properties that make them attractive for future optoelectronic applications. Integration of TMDCs into practical all-dielectric heterostructures hinges on the ability to passivate and protect them against necessary fabrication steps on large scales. Despite...

We report the observation of low-energy, low-momenta collective oscillations of an exciton-polariton condensate in a round "box" trap. The oscillations are dominated by the dipole and breathing modes, and the ratio of the frequencies of the two modes is consistent with that of a weakly interacting two-dimensional trapped Bose gas. The speed of soun...

We demonstrate an experimental approach to create dissipative solitons in a microcavity laser. In particular, we shape the spatial gain profile of a quasi-one-dimensional microcavity laser with a nonresonant, pulsed optical pump to create spatially localised structures, called gain-pinned dissipative solitons that exist due to the balance of gain a...

The property of superfluidity, first discovered in liquid 4He, is closely related to the Bose-Einstein condensation (BEC) of interacting bosons1. However, even at zero temperature, when the whole bosonic quantum liquid would become superfluid, only a fraction of it would remain Bose-condensed at zero momentum. This is due to the quantum depletion p...

We provide an analytical and numerical description of relaxation oscillations in the nonresonantly pumped polariton condensate. The presented considerations are based on the open dissipative Gross-Pitaevskii equation coupled to a pair of rate equations. The evolution of the condensate density can be explained qualitatively by studying the topology...

We study theoretically the emission of dark solitons induced by a moving defect in a nonresonantly pumped exciton-polariton condensate. The number of created dark solitons per unit of time is found to be strongly dependent on the pump power. We relate the observed dynamics of this process to the oscillations of the drag force experienced by the con...

The lateral interdot coupling is investigated in high density (~10 cm⁻² ) self-assembled InAs quantum dots (QDs) grown on an InP substrate. Two types of structures are selected for this study, in which QDs are embedded into an InAlAs matrix, forming nearly twice stronger confinement for an electron and a hole than expected for an InAlGaAs counterpa...

We report a systematic study of the temperature and excitation density behavior of an AlAs/AlGaAs, vertically emitting microcavity with embedded ternary Al0.20Ga0.80As/AlAs quantum wells in the strong coupling regime. Temperature-dependent photoluminescence measurements of the bare quantum wells indicate a crossover from the type-II indirect to the...

Semiconductor microcavities are often influenced by structural imperfections, which can disturb the flow and dynamics of exciton-polariton condensates. Additionally, in exciton-polariton condensates there is a variety of dynamical scenarios and instabilities, owing to the properties of the incoherent excitonic reservoir. We investigate the dynamics...

The lateral carrier diffusion process is investigated in coupled InGaAs/GaAs quantum dot-quantum
well (QD-QW) structures by means of spatially resolved photoluminescence spectroscopy at low
temperature. Under non-resonant photo-excitation above the GaAs bandgap, the lateral carrier
transport reflected in the distorted electron-hole pair emission pr...

In this report we present experimental studies on the energy transfer between the wetting layer and single large elongated In0.3Ga0.7As/GaAs quantum dots. We obtain insight into the electronic and optical properties of In0.3Ga0.7As/GaAs quantum dots by probing their confined electronic states via photoluminescence excitation spectroscopy on the sin...

We investigate double layer InAs/GaAs quantum dots grown in the Stransky-Krastanov mode by molecular beam epitaxy. The sample consists of two layers of InAs quantum dots separated by 10 nm thick GaAs layer, where the top quantum dot layer of an improved homogeneity is covered by an InGaAs cap. This configuration has allowed for the extension of the...

An expanding polariton condensate is investigated under pulsed nonresonant excitation with a small
laser pump spot. Far above the condensation threshold we observe a pronounced increase in the dispersion
curvature, with a subsequent linearization of the spectrum and strong luminescence from a ghost branch
orthogonally polarized with respect to the...

Realization of the Bose�Einstein condensate can provide a way for creation of an inversion-free coherent
light emitter with ultra-low threshold power. The currently considered solutions provide polaritonic emitters in a
spectral range far below 1 �m limiting their application potential. Hereby, we present optical studies of InGaAs/
GaAs based quant...

In this contribution the electronic structure of large In0:3Ga0:7As/GaAs quantum dots is studied theoretically
by means of 8 band k.p modeling. These quantum dots constitute unique physical system due to the low
strain limit of the Stranski-Krastanow growth mode resulting in relatively large physical volume and elongation
of the quantum dots in [1...

We demonstrate room temperature, continuous wave lasing of laser diodes based on AlGaAswhispering gallery mode(WGM)resonators (microcylinder and microring) embedding a quantum dot(QD)active layer. Using InGaAlAs QDs, high-Q (>60 000) lasing modes are observed around 910 nm, up to 50 °C. Lasing with similar performance is obtained around 1230 nm, us...