Below you'll see everything we could locate for your search of “exciton”
Ground-breaking research revealed the ultra-narrow linewidth of a novel type of laser that operates without population inversion. Exciton-polariton lasers, renowned for their low-power operation, have long tantalised researchers with their promise for practical low-energy applications. However, until now, a clean measurement of the laser’s linewidth, or spectral purity, has remained elusive. “The spectral purity is one of the defining characteristics …
A team of Monash researchers have uncovered for the first time the full effects of interactions between exciton-polaritons and their associated dark excitonic reservoir. Exciton-polaritons (‘polaritons’, for short) are hybrid mixtures of light and matter that inherit the best properties of both. They form in semiconductors sandwiched between two mirrors, through which a laser is shone. “Polaritons capture useful properties …
The FLEET-EU 2023 Conference : Transport in exciton condensates and exciton insulators took place on September 11, 2023 in San Benedetto del Tronto, the art-deco resort town known as the Riviera of the Palms situated on the Italian Adriatic coast. The conference was jointly organised by University of Camerino (Italy), University of Antwerp (Belgium), and FLEET, and covered a range …
Kyle Boschen completed his Honours project in 2022 and is now undertaking a PhD in CI Jeff Davis‘ group. He is investigating the properties of two dimensional semiconducting TMDs using ultrafast spectroscopy. The project fits the FLEET Enabling Research Theme 2, Exciton Superfluids
Recent evidence suggests monolayer WTe2 could be an excitonic insulator. If so, carrier doping and interaction with the substrate should heavily affect the bandgap. The Bose-Einstein condensate of excitons are predicted to exhibit charge order with a characteristic momentum. When grown on an insulator as opposed to a conductor, we have observed the formation of a significantly larger (∼ 200 …
The excitonic resonances in 2D TMDs are known to be dependent on magnetic field, often described with a simplified Hamiltonian featuring a diamagnetic term quadratic in B. This simple picture is sufficient for 1s excitons in realistic laboratory conditions, however it fails to capture the behaviour of higher order excitons even at moderate magnetic field strength. In this work we …
Here, we demonstrate up-conversion photoluminescence of optically forbidden (dark) excitons in few-layer transition metal dichalcogenides. Transition metal dichalcogenides were mechanically exfoliated onto sapphire substrates using a dry transfer technique. We show that the resonance between up-converted excitons and the bright exciton state at Γ valley results in a strongly enhanced photoluminescence, evidenced by temperature, layer and excitation dependent photoluminescence measurements. …
About the presenter Yow-Ming (Robin) Hu is a PhD student working with Chief Investigator Elena Ostrovskaya. Her project aims to characterise the topology of an exciton-polariton system and to show how to calculate and measure its quantum geometric tensor, including complex Berry curvature. This works towards a key objective of FLEET Research Theme 2 Exciton Superfluids to observe, theoretically and …
Optical properties of dark excitons in transition metal dichalcogenides (TMDs) have been received lots of attention due to its significant role in fundamental properties of exciton physics. Here, we demonstrate up-converted photoluminescence (PL) in few-layer WSe2 through exciton-exciton annihilation of intervalley dark excitons. WSe2 was mechanically exfoliated onto silicon substrates with 285-nm-thick SiO2 using a dry transfer technique. We performed …
About the presenter Bianca is a PhD candidate in CI Elena Ostrovskaya‘s group. Her project aims to realise, experimentally, exciton polaritons in artificial lattices and observe novel topologically protected states. This work fits the FLEET Enabling Research Theme 2, Exciton Superfluids.
About the presenter Kenneth is a PhD candidate in CI Meera Parish‘s group. His research aims to investigate the interactions between excitons (or exciton-polaritons), and 2-D electron gas, with a view to inducing a collective, dissipationless flow of charged bosons: exciton-mediated superconductivity.
About the presenter Dr Eliezer Estrecho is a DECRA Fellow at the Australian National University and a Research Fellow of FLEET. His research interests are mainly on exciton-polariton condensates, non-Hermitian physics, and strong light-matter interaction, specifically between electronic excitations (excitons) and photonic modes.
Optical properties of dark excitons in transition metal dichalcogenides (TMDs) have been received lots of attention due to its significant role in fundamental properties of exciton physics. Here, we demonstrate up-converted photoluminescence (PL) in n-layer WSe2 (n > 2) through exciton-exciton annihilation of dark excitons. Few-layer WSe2 were mechanically exfoliated onto silicon substrates with 285-nm-thick SiO2 using a dry transfer …
Using light to control non-equilibrium phenomena in quantum systems is at the forefront of condensed matter research. Here we utilise MDCS to create an inter-valley coherence in monolayer WS2 and measure the pump induced changes to the coherent exciton dynamics. About the presenter Mitchell Conway is a Research Fellow at Swinburne University with CI Jeff Davis. He just completed his …
Recent evidence suggests monolayer WTe2 could be an excitonic insulator. While this theory is controversial, if correct, the excitonic condensate should exhibit a charge density wave (CDW) and should collapse with electron doping. Through scanning tunnelling microscopy (STM) and angle-resolved photoelectron spectroscopy (ARPES) we display evidence of these phenomena and are making progress toward confirming their excitonic nature with theoretical …
Exciton-polaritons (polaritons herein) are bosonic quasiparticles formed when an exciton is coupled to a cavity photon in a semiconductor microcavity [1]. These hybrid light-matter quasiparticles form Bose-Einstein condensates at elevated temperatures due to their very small effective mass. However, polariton condensates are inherently non-equilibrium because of the ultrashort lifetime of polaritons and coexistence with a reservoir of high-energy excitons feeding …
Atomically-thin InSe exhibited strong PL emission from its dark excitons due to efficient acoustic-phonon-exciton coupling, resulting in high population density and efficient radiative recombination. The asymmetric lineshape observed in the PL emission is explained by the carrier localization model, attributed to nonuniform surface potentials. About the presenter Shao-Yu Chen is a Scientific Associate Investigator from the National Taiwan University, collaborating …
We investigate the formation of excitons bound by photons using a microscopic Hamiltonian involving quantum well electrons, holes, and microcavity photons. The negative reduced effective mass of the quantum well electron-hole (e-h) pair prevents Coulomb bound excitonic states, but the microcavity photon is capable of inducing binding. Using a theory based on Green’s functions we have calculated the spectral response …
We investigate interactions between polaritons and a dark excitonic reservoir in a 2D system where the excitons are tightly-bound. The resulting energy spectrum is found to display several interesting features, including the appearance of a new energy mode related to a biexcitonic bound state, an apparent reduction in the Rabi splitting between the lower and upper polariton branches as the …
About the presenter Jack is a PhD candidate in CI Oleg Sushkov‘s group. His project aims to establish a theoretical groundwork for magnetohydrodynamics in 2D electron fluids using periodic micromagnets. This work fits the FLEET Enabling Research Theme 1, Topological Materials.
About the presenter Yow-Ming (Robin) Hu is an Honours student working with Chief Investigator Elena Ostrovskaya. Her project aims to characterise the topology of an exciton-polariton system and to show how to calculate and measure its quantum geometric tensor, including complex Berry curvature. This works towards a key objective of FLEET Research Theme 2 Exciton Superfluids to observe, theoretically and …
About the presenter Prof Justin Hodgkiss uses ultrafast optical spectroscopy at the Victoria University of Wellington in search of molecular electronic materials for new, low-cost printable electronics – primarily solar cells. His group invented transient grating ultrafast fluorescence spectroscopy and has used laser spectroscopy to develop a detailed understanding of the physics of photocurrent generation in printable solar cells. Prof …
About the presenter Prof Francois Peeters is a member of FLEET’s International Scientific Advisory Committee. He leads the Condensed Matter Theory Group at the University of Antwerp and also distinguished Professor at Yunnan University. Prof Peeters has made seminal contributions in areas of meso- and nano-physics of semiconductors, two dimensional materials and superconductors. Currently, his interest is in two-dimensional atomic …
About the presenter Kenneth is a PhD candidate in CI Meera Parish‘s group. His research aims to investigate the interactions between excitons (or exciton-polaritons), and 2-D electron gas, with a view to inducing a collective, dissipationless flow of charged bosons: exciton-mediated superconductivity.
Prof. Yuerui (Larry) Lu, School of Engineering, Australian National University (ANU) Missed the seminar? Catch up on FLEET’s YouTube. Abstract Strong, long-range dipole-dipole interactions between interlayer excitons (IXs) can lead to novel multi-particle correlation regimes that drive the system into distinct quantum and classical phases including dipolar liquids, crystals, and superfluids. Both repulsive and attractive dipole-dipole interactions have been theoretically …
Dr Eli Estrecho, FLEET research Fellow, Polariton BEC Group, Australian National University Missed the talk? Catch-up on YouTube Losses are known to be detrimental to devices but judiciously controlling them can lead to counterintuitive gains. For example, by increasing loss, lossy materials can become transparent or a lossy laser can turn on again. In this seminar, I will discuss our …
Dr Harley Scammell, UNSW Missed the talk? Catch up on YouTube By analogy with BCS superconductivity, it has long been expected that excitons condense in (nearly) particle-hole symmetric two-dimensional semimetals. However, in the absence of a magnetic field, very few examples are known. And I will not be providing one. Instead, I will propose an alternate route to exciton condensation. …
Matthias Wurdack, FLEET Research Fellow, Australian National University 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, their excitons can hybridise with cavity photons to form exciton polaritons (polaritons herein), which could be …
