arXiv subjects

M. S. Skolnick

Publications and source records attributed to M. S. Skolnick.

At least 19 recordsLinked to original sources

arXiv2026

Controlling coherence between waveguide-coupled quantum dots

We present a novel waveguide design that incorporates a split-diode structure, allowing independent electrical control of transition energies of multiple emitters over a wide range with minimal loss in waveguide coupling efficiency. We use this design to systematically map out the transition from superradiant to independent emission from two quantum dots. We perform both lifetime as well as Hanbury Brown-Twiss measurements on the device, observing anti-dips in the photon coincidences indicating collective emission while at the same time observing a drop in lifetime around zero detuning, indicating superradiant behaviour. Performing both measurement types allows us to investigate detuning regions which show both superradiant rate enhancement and inter-emitter coherence, as well as regions in which correlations persist in the absence of rate enhancement.

quant-ph↗

arXiv2025

Stark Tuning and Charge State Control in Individual Telecom C-Band Quantum Dots

Telecom wavelength quantum dots (QDs) are emerging as a promising solution for generating deterministic single photons compatible with existing fiber optic infrastructure. Emission in the low loss C band minimizes transmission losses, making them ideal for long distance quantum communication. In this work, we present a demonstration of both Stark tuning and charge state control of individual InAs/InP QDs operating within the telecom C-band. These QDs are grown by droplet epitaxy and embedded in an InP based n++-i-n+ heterostructure fabricated using MOVPE. The gated architecture enables the tuning of emission energy via the quantum confined Stark effect, with a tuning range exceeding 2.4 nm. It also allows for control over the QD charge occupancy, enabling access to multiple discrete excitonic states. Electrical tuning of the fine structure splitting is further demonstrated, opening a route to entangled photon pair generation at telecom wavelengths. The single photon character is confirmed via second order correlation measurements. These advances enable QDs to be tuned into resonance with other systems, such as cavity modes and emitters, marking a critical step toward scalable, fiber compatible quantum photonic devices.

quant-ph↗

arXiv2025

Chiral Quantum Optics with Scalable Quantum Dot Dimers

We present a scalable method for electrically tuning multiple spatially separated quantum dots embedded in photonic crystal waveguides. Ion implantation into the top p-doped layer of a p-i-n diode creates high-resistivity tracks, providing electrical isolation between adjacent regions. Unlike physical etching, this method preserves the guided-mode profile of the photonic crystal without introducing significant scattering, limiting refractive index perturbations to below 0.001 with 0.01% additional loss. In contrast, physical etching can reduce single-band transmission by more than 30% for an etch width of 100 nm. We demonstrate the applicability of our approach using quantum dots embedded in a glideplane photonic crystal waveguide, controlling the detuning between different spin-state combinations of two highly chiral quantum dots coupled to the same mode. Second-order photon correlation measurements provide a sensitive probe of the chirality-dependent photon statistics, which are in good agreement with a waveguide-QED master equation model. Our results mark an important step towards scalable, multi-emitter architectures for chiral quantum networks.

physics.optics↗

arXiv2025

Topological and conventional nano-photonic waveguides for directional integrated quantum optics

Chirality in integrated quantum photonics has emerged as a promising route towards achieving scalable quantum technologies with quantum nonlinearity effects. Topological photonic waveguides, which utilize helical optical modes, have been proposed as a novel approach to harnessing chiral light-matter interactions on-chip. However, uncertainties remain regarding the nature and strength of the chiral coupling to embedded quantum emitters, hindering the scalability of these systems. In this work, we present a comprehensive investigation of chiral coupling in topological photonic waveguides using a combination of experimental, theoretical, and numerical analyses. We quantitatively characterize the position-dependence nature of the light-matter coupling on several topological photonic waveguides and benchmark their chiral coupling performance against conventional line defect waveguides for chiral quantum optical applications. Our results provide crucial insights into the degree and characteristics of chiral light-matter interactions in topological photonic quantum circuits and pave the way towards the implementation of quantitatively-predicted quantum nonlinear effects on-chip.

physics.optics↗

arXiv2024

Nonlinear Quantum Optics at a Topological Interface Enabled by Defect Engineering

The integration of topology into photonics has generated a new design framework for constructing robust and unidirectional waveguides, which are not feasible with traditional photonic devices. Here, we overcome current barriers to the successful integration of quantum emitters such as quantum dots (QDs) into valley-Hall (VH) topological waveguides, utilising photonic defects at the topological interface to stabilise the local charge environment and inverse design for efficient topological-conventional mode conversion. By incorporating QDs within defects of VH-photonic crystals, we demonstrate the first instances of single-photon resonant fluorescence and resonant transmission spectroscopy of a quantum emitter at a topological waveguide interface. Our results bring together topological photonics with optical nonlinear effects at the single-photon level, offering a new avenue to investigate the interaction between topology and quantum nonlinear systems.

physics.optics↗

arXiv2023

Exciton-polaritons in GaAsbased slab waveguide photonic crystals

We report the observation of band gaps for low loss exciton-polaritons propagating outside the light cone in GaAs-based planar waveguides patterned into two-dimensional photonic crystals. By etching square lattice arrays of shallow holes into the uppermost layer of our structure, we open gaps on the order of 10 meV in the photonic mode dispersion, whose size and light-matter composition can be tuned by proximity to the strongly coupled exciton resonance. We demonstrate gaps ranging from almost fully photonic to highly excitonic. Opening a gap in the exciton-dominated part of the polariton spectrum is a promising first step towards the realization of quantum-Hall-like states arising from topologically nontrivial hybridization of excitons and photons.

physics.optics↗

arXiv2022

Nonlinear self-action of ultrashort guided exciton-polariton pulses in dielectric slab coupled to 2D semiconductor

Recently reported large values of exciton-polariton nonlinearity of transition metal dichalcogenide (TMD) monolayers coupled to optically resonant structures approach the values characteristic for GaAs-based systems in the regime of strong light-matter coupling. Contrary to the latter, TMD-based polaritonic devices remain operational at ambient conditions and therefore have greater potential for practical nanophotonic applications. Here we present the study of the nonlinear properties of Ta$_2$O$_5$ slab waveguide coupled to a WSe$_2$ monolayer. We first confirm that the hybridization between waveguide photon mode and a 2D semiconductor exciton resonance gives rise to the formation of exciton-polaritons with Rabi splitting of 36 meV. By measuring transmission of ultrashort optical pulses through this TMD-based polaritonic waveguide, we demonstrate for the first time the strong nonlinear dependence of the output spectrum on the input pulse energy. Our theoretical model provides semi-quantitative agreement with experiment and gives insights into the dominating microscopic processes which determine the nonlinear pulse self-action: Coulomb inter-particle interaction and scattering to incoherent excitonic reservoir. We also confirm that at intermediate pump energies the system supports quasi-stationary solitonic regime of pulse propagation. Our results are essential for the development of nonlinear on-chip polaritonic devices based of 2D semiconductors.

cond-mat.mes-hall↗

arXiv2022

Engineering strong chiral light-matter interactions in a waveguide-coupled nanocavity

Spin-dependent, directional light-matter interactions form the basis of chiral quantum networks. In the solid state, quantum emitters commonly possess circularly polarised optical transitions with spin-dependent handedness. We demonstrate numerically that spin-dependent chiral coupling can be realised by embedding such an emitter in a waveguide-coupled nanocavity, which supports two near-degenerate, orthogonally-polarised cavity modes. The chiral behaviour arises due to direction-dependent interference between the cavity modes upon coupling to two single-mode output waveguides. Notably, an experimentally realistic cavity design simultaneously supports near-unity chiral contrast, efficient ($β> 0.95$) waveguide coupling and enhanced light-matter interaction strength (Purcell factor $F_P > 70$). In combination, these parameters could enable the development of highly coherent spin-photon interfaces, ready for integration into nanophotonic circuits.

physics.optics↗

arXiv2021

A chiral topological add-drop filter for integrated quantum photonic circuits

The integration of quantum emitters within topological nano-photonic devices opens up new avenues for the control of light-matter interactions at the single photon level. Here, we realise a spin-dependent, chiral light-matter interface using individual semiconductor quantum dots embedded in a topological add-drop filter. The filter is imprinted within a valley-Hall photonic crystal (PhC) membrane and comprises a resonator evanescently coupled to a pair of access waveguides. We show that the longitudinal modes of the resonator enable the filter to perform wavelength-selective routing of light, protected by the underlying topology. Furthermore, we demonstrate that for a quantum dot located at a chiral point in the resonator, selective coupling occurs between well-defined spin states and specific output ports of the topological device. This behaviour is fundamental to the operation of chiral devices such as a quantum optical circulator. Our device therefore represents a topologically-protected building block with potential to play an enabling role in the development of chiral integrated quantum photonic circuits.

physics.optics↗

arXiv2020

Optical analogue of Dresselhaus spin-orbit interaction in photonic graphene

The concept of gauge fields plays a significant role in many areas of physics from particle physics and cosmology to condensed matter systems, where gauge potentials are a natural consequence of electromagnetic fields acting on charged particles and are of central importance in topological states of matter. Here, we report on the experimental realization of a synthetic non-Abelian gauge field for photons in a honeycomb microcavity lattice. We show that the effective magnetic field associated with TE-TM splitting has the symmetry of Dresselhaus spin-orbit interaction around Dirac points in the dispersion, and can be regarded as an SU(2) gauge field. The symmetry of the field is revealed in the optical spin Hall effect (OSHE), where under resonant excitation of the Dirac points precession of the photon pseudospin around the field direction leads to the formation of two spin domains. Furthermore, we observe that the Dresselhaus field changes its sign in the same Dirac valley on switching from s to p bands in good agreement with the tight binding modelling. Our work demonstrating a non-Abelian gauge field for light on the microscale paves the way towards manipulation of photons via spin on a chip.

cond-mat.mes-hall↗

arXiv2020

Spin-valley dynamics in alloy-based transition metal dichalcogenide heterobilayers

Van der Waals heterobilayers based on 2D transition metal dichalcogenides have been recently shown to support robust and long-lived valley polarization for potential valleytronic applications. However, the role of the band structure and alignment of the constituent layers in the underlying dynamics remains largely unexplored. Here we study spin--valley relaxation dynamics in heterobilayers with different band structures engineered via the use of alloyed monolayer semiconductors. Through a combination of time-resolved Kerr rotation spectroscopic measurements and theoretical modelling for Mo$_{1-x}$W$_{x}$Se$_2$/WSe$_2$ samples with different chemical compositions and stacking angles, we uncover the roles of interlayer exciton recombination and charge carrier spin depolarization in the overall valley dynamics. Our results provide insights into the microscopic spin--valley polarization mechanisms in van der Waals heterostructures for the development of future 2D valleytronic devices.

cond-mat.mes-hall↗

arXiv2020

A Semiconductor Topological Photonic Ring Resonator

Unidirectional photonic edge states arise at the interface between two topologically-distinct photonic crystals. Here, we demonstrate a micron-scale GaAs photonic ring resonator, created using a spin Hall-type topological photonic crystal waveguide. Embedded InGaAs quantum dots are used to probe the mode structure of the device. We map the spatial profile of the resonator modes, and demonstrate control of the mode confinement through tuning of the photonic crystal lattice parameters. The intrinsic chirality of the edge states makes them of interest for applications in integrated quantum photonics, and the resonator represents an important building block towards the development of such devices with embedded quantum emitters.

physics.optics↗

arXiv2019

Highly nonlinear trion-polaritons in a monolayer semiconductor

Highly nonlinear optical materials with strong effective photon-photon interactions (Kerr-like nonlinearity) are required in the development of novel quantum sources of light as well as for ultrafast and quantum optical signal processing circuitry. Here we report very large Kerr-like nonlinearities by employing strong optical transitions of charged excitons (trions) observed in semiconducting transition metal dichalcogenides (TMDCs). By hybridising trions in monolayer MoSe$_2$ at low electron densities with a microcavity mode, we realise trion-polaritons exhibiting significant energy shifts at very small photon fluxes due to phase space filling. Most notably, the strong trion-polariton nonlinearity is found to be 10 to 1000 larger than in other polariton systems, including neutral exciton-polaritons in TMDCs. Furthermore it exceeds by factors of $\sim 10^3-10^5$ the magnitude of Kerr nonlinearity in bare TMDCs, graphene and other widely used optical materials (e.g. Si, AlGaAs etc) in weak light-matter coupling regimes. The results are in good agreement with a theory which accounts for the composite nature of excitons and trions and deviation of their statistics from that of ideal bosons and fermions. This work opens a new highly nonlinear system for quantum optics applications enabling in principle scalability and control through nano-engineering of van der Waals heterostructures.

cond-mat.mes-hall↗

arXiv2019

Nonlinear polaritons in monolayer semiconductor coupled to optical bound states in the continuum

Optical bound states in the continuum (BICs) provide a way to engineer very narrow resonances in photonic crystals. The extended interaction time in such systems is particularly promising for enhancement of nonlinear optical processes and development of the next generation of active optical devices. However, the achievable interaction strength is limited by the purely photonic character of optical BICs. Here, we mix optical BIC in a photonic crystal slab with excitons in atomically thin semiconductor MoSe$_2$ to form nonlinear exciton-polaritons with a Rabi splitting of 27~meV, exhibiting large interaction-induced spectral blueshifts. The asymptotic BIC-like suppression of polariton radiation into far-field towards the BIC wavevector, in combination with effective reduction of excitonic disorder through motional narrowing, results in small polariton linewidths below 3~meV. Together with strongly wavevector-dependent Q-factor, this provides for enhancement and control of polariton--polariton interactions and resulting nonlinear optical effects, paving the way towards tunable BIC-based polaritonic devices for sensing, lasing, and nonlinear optics.

cond-mat.mes-hall↗

arXiv2019

Measurement of local optomechanical properties of a direct bandgap 2D semiconductor

Strain engineering is a powerful tool for tuning physical properties of 2D materials, including monolayer transition metal dichalcogenides (TMD) -- direct bandgap semiconductors with strong excitonic response. Here, we demonstrate an approach for local characterization of strain-induced modification of excitonic photoluminescence in TMD-based materials. We reversibly stress a monolayer of MoSe$_2$ with an AFM tip and perform spatio-spectral mapping of the excitonic photoluminescence in the vicinity of the indentation point. To fully reproduce the experimental data, we introduce the linear dependence of the exciton energy and corresponding photoluminescence intensity on the induced strain. Careful account for the optical resolution allows extracting these quantities with good agreement with the previous measurements, which involved macroscopic sample deformation. Our approach is a powerful tool for the study of local optomechanical properties of 2D direct bandgap semiconductors with strong excitonic response.

cond-mat.mes-hall↗

arXiv2019

Tunable photon statistics exploiting the Fano effect in a waveguide

A strong optical nonlinearity arises when coherent light is scattered by a semiconductor quantumdot (QD) coupled to a nano-photonic waveguide. We exploit the Fano effect in such a waveguide to control the phase of the quantum interference underpinning the nonlinearity, experimentally demonstrating a tunable quantum optical filter which converts a coherent input state into either a bunched, or antibunched non-classical output state. We show theoretically that the generation of non-classical light is predicated on the formation of a two-photon bound state due to the interaction of the input coherent state with the QD. Our model demonstrates that the tunable photon statistics arise from the dependence of the sign of two-photon interference (either constructive or destructive) on the detuning of the input relative to the Fano resonance.

quant-ph↗

arXiv2018

Effect of photonic spin-orbit coupling on the topological edge modes of a Su-Schrieffer-Heeger chain

We study the effect of photonic spin-orbit coupling (SOC) in micropillar lattices on the topological edge states of a one-dimensional chain with a zigzag geometry, corresponding to the Su-Schrieffer-Heeger model equipped with an additional internal degree of freedom. The system combines the strong hopping anisotropy of the $p$-type pillar modes with the large TE-TM splitting in Bragg microcavities. By resolving the photoluminescence emission in energy and polarization we probe the effects of the resulting SOC on the spatial and spectral properties of the edge modes. We find that the edge modes feature a fine structure of states that penetrate by different amounts into the bulk of the chain, depending on the strength of the SOC terms present, thereby opening a route to manipulation of the topological states in the system.

physics.optics↗

arXiv2018

Spin domains in one-dimensional conservative polariton solitons

We report stable orthogonally polarised domains in high-density polariton solitons propagating in a semiconductor microcavity wire. This effect arises from spin dependent polariton-polariton interactions and pump-induced imbalance of polariton spin populations. The interactions result in an effective magnetic field acting on polariton spin across the soliton profile, leading to the formation of polarisation domains. Our experimental findings are in excellent agreement with theoretical modelling taking into account these effects.

cond-mat.mes-hall↗