arXiv subjects

Jonathan Beaumariage

Publications and source records attributed to Jonathan Beaumariage.

At least 19 recordsLinked to original sources

arXiv2026

Counterdirectional Exciton and Trion Motion in Applied Electric Field

Charged excitonic complexes are central to the optoelectronic and many-body properties of semiconductors, yet their real-space transport dynamics remain largely unexplored. Here, we report the direct optical observation of trion motion under an applied electric field. The trions exhibit electrically driven drift with velocities approaching {$10^5~\mathrm{m/s}$}. Unexpectedly, the trion flow induces a pronounced back-action on coexisting neutral excitons, driving them in the opposite direction and giving rise to counterpropagating exciton-trion transport. Our results reveal an interaction-driven nonequilibrium transport regime of mixed excitonic fluids and establish a direct route for imaging the dynamics of more complex charged quasiparticles, including doubly charged excitons.

physics.optics↗

arXiv2026

Temporal hopping dynamics in exciton-polariton condensation

Polariton condensates provide a versatile platform for exploring non-equilibrium phase transitions and collective phenomena in open quantum systems. Near the condensation threshold, these systems are particularly sensitive to fluctuations and instabilities, which can strongly influence the condensate formation. Using optical trapping and homodyne detection, we directly access the photon statistics and second-order correlation function $g^{(2)}(0)$ of the condensate. We show that polariton condensation near the threshold is not a purely static transition, but instead undergoes a dynamical regime characterized by stochastic hopping between condensed and non-condensed states. These intermittent dynamics are accompanied by a gradual reduction of $g^{(2)}(0)$ towards unity, revealing the progressive build-up of coherence even in the presence of strong temporal fluctuations. Numerical simulations, based on a stochastic Truncated Wigner description of the driven-dissipative polariton field, reproduce these dynamics and capture the essential role of noise and reservoir interactions. This work demonstrates that the observed temporal hopping is an intrinsic feature of polariton condensation, providing a dynamical perspective that goes beyond static descriptions of the condensation phase transition.

cond-mat.mes-hall↗

arXiv2026

Four Generations of Quantum Biomedical Sensors

Quantum sensing technologies offer transformative potential for ultra-sensitive biomedical sensing, yet their clinical translation remains constrained by classical noise limits and a reliance on macroscopic ensembles. We propose a unifying generational framework to organize the evolving landscape of quantum biosensors based on their utilization of quantum resources. First-generation devices utilize discrete energy levels for signal transduction but follow classical scaling laws. Second-generation sensors exploit quantum coherence, extending precision with the coherence time up to the standard quantum limit, while third-generation architectures employ entanglement and spin squeezing to approach Heisenberg-limited precision. We define an emerging fourth generation characterized by the end-to-end integration of quantum sensing with quantum learning and variational circuits, enabling adaptive inference directly within the quantum domain. By introducing a bandwidth-matching analysis pairing the neural signal hierarchy with platform response bandwidths, classifying deployed clinical devices by precision-scaling class and sensor-tissue proximity, and outlining a staged physical-milestone roadmap toward learning-integrated sensor networks, we identify key technological bottlenecks and chart the transition from measuring physical observables to extracting structured biological information with quantum-enhanced intelligence.

quant-ph↗

arXiv2026

Achieving Sub-Zeptonewton Force Sensitivity and Spin-Motion Entanglement in Levitated Diamond via Pulsed Backaction Evasion

We propose a system to achieve sub-zeptonewton force sensing and robust spin-mechanical entanglement in a levitated diamond system. By coupling a nitrogen-vacancy (NV) center spin to the motion of its host diamond within a magnetic trap, we develop a platform designed to surpass the standard quantum limit. We develop and compare three distinct pulse sequences -- Ramsey, Hahn echo, and Carr-Purcell-Meiboom-Gill (CPMG) -- to create increasing amounts of backaction evasion while mitigating the effects of shot noise and thermal decoherence. Our results show that the CPMG sequences yield the most significant performance gains, reaching a force sensitivity of better than $10^{-23} \text{ N}/\sqrt{\text{Hz}}$ for broadband sensing around $10^4 \text{ Hz}$. Furthermore, we derive an entanglement witness protocol that accounts for pulsed dynamical decoupling, proving that spin-motion entanglement remains detectable even when occurring much faster than the mechanical period. These findings provide a more practical path for using levitated nanodiamonds both as high-precision sensors and as non-classical mechanical systems for fundamental tests of quantum mechanics.

quant-ph↗

arXiv2026

Controlled Switching of Bose-Einstein Condensation in a Mixture of Two Species of Polaritons

We report temperature-dependent switching between lower and upper polariton condensation in a GaAs/AlGaAs microcavity when both of these species have comparable populations in a mixture. Using angle-resolved photoluminescence, we observe that at low temperatures, condensation occurs in the lower polariton branch, while at elevated temperatures, the upper polariton branch can become favored. At an intermediate temperature, we observe instability in the condensate formation, characterized by metastable correlations of the fluctuations in intensity and linewidth of the lower and upper polariton branches.

cond-mat.quant-gas↗

arXiv2025

Mirror-mediated long-range coupling and robust phase locking of spatially separated exciton-polariton condensates

Lattice arrays are valuable simulators for complex mathematical problems, but physical systems typically allow only short-range coupling. We demonstrate a method for independently tunable, long-range interactions between polariton condensates in two-dimensional lattices by using vertical emission and external imaging to couple arbitrary sites. Two geometrically isolated condensates are phase-locked without planar coupling, verified via phase-resolved interferometry. Analytical modeling reveals mechanisms for robust coherence. The mirror-based scheme, free of cameras or modulators, offers a pure, high-bandwidth analogt element. Extension to dense graphs via segmented micro-mirrors is limited only by imaging optics, enabling scalable, energy-efficient polaritonic hardware for neuromorphic computation.

physics.optics↗

arXiv2025

Strong coupling of polaritons at room temperature in a GaAs/AlGaAs structure

We report direct measurement of the dispersion relation of polaritons in GaAs/AlGaAs microcavity structures at room temperature, which clearly shows that the polaritons are in the strong coupling limit. The Rabi splitting of the polariton states decreases as the polariton gas increases in density, but even when the polariton gas becomes a coherent, Bose-condensate-like state, the polaritons retain a strong exciton component, as seen in the nonlinear energy shift of the light emission. This opens up the possibility of polaritonic devices at room temperature in a material system which can be grown with very high quality and uniformity.

cond-mat.mes-hall↗

arXiv2024

Light-Induced Electron Pairing in a Bilayer Structure

Previous experimental and theoretical work has given evidence of the existence of doubly charged exciton states in strongly screened bilayers of transition metal dichalcogenide (TMD) layers. These complexes are important because they are performed electron pairs that can, in principle, undergo Bose-Einstein condensation (BEC), in which case they would also form a new type of superconductor, consisting of stable bosons with net charges. In this paper, we present key electrostatic and magnetic measurements that definitively confirm the existence of these charged bosons. These measurements include 1) continuous control of the doping density with both positive and negative carriers, showing the expected population dependencies on the free carrier density, and 2) measurement of the dependence on the magnetic field, showing that this new bound state is a spin triplet. These results imply that it is promising to look for BEC and superconductivity in this system.

cond-mat.supr-con↗

arXiv2024

Targeted Polariton Flow Through Tailored Photonic Defects

In non-Hermitian open quantum systems, such as polariton condensates, local tailoring of gains and losses opens up an interesting possibility to realize functional optical elements. Here, we demonstrate that deliberately introducing losses via a photonic defect, realized by reducing the quality factor of a DBR mirror locally within an ultrahigh-quality microcavity, may be utilized to create directed polariton currents towards the defect. We discuss the role of polariton-polariton interactions in the process and how to tailor the effective decay time of a polariton condensate via coupling to the defect. Our results highlight the far-reaching potential of non-Hermitian physics in polaritonics.

cond-mat.mes-hall↗

arXiv2024

Quantum coherence of a long-lifetime exciton-polariton condensate

In recent years, quantum information science has made significant progress, leading to a multitude of quantum protocols for the most diverse applications. States carrying resources such as quantum coherence are a key component for these protocols. In this study, we optimize the quantum coherence of a nonresonantly excited exciton-polariton condensate of long living polaritons by minimizing the condensate's interaction with the surrounding reservoir of excitons and free carriers. By combining experimental phase space data with a displaced thermal state model, we observe how quantum coherence builds up as the system is driven above the condensation threshold. Our findings demonstrate that a spatial separation between the condensate and the reservoir enhances the state's maximum quantum coherence directly beyond the threshold. These insights pave the way for integrating polariton systems into hybrid quantum devices and advancing applications in quantum technologies.

cond-mat.mes-hall↗

arXiv2024

Bose-Einstein condensation of polaritons at room temperature in a GaAs/AlGaAs structure

We report the canonical properties of Bose-Einstein condensation of polaritons, seen previously in many low-temperature experiments, at room temperature in a GaAs/AlGaAs structure. These effects include a nonlinear energy shift of the polaritons, showing that they are not non-interacting photons, and dramatic line narrowing due to coherence, giving coherent emission with spectral width of 0.24 meV at room temperature with no external stabilization. This opens up the possibility of room temperature nonlinear optical devices based on polariton condensation.

cond-mat.quant-gas↗

arXiv2024

Measurement of exciton fraction of microcavity exciton-polaritons using transfer-matrix modeling

We present a careful calibration of the exciton fraction of polaritons in high-$Q$ ($\sim 300,000$), long-lifetime ($\sim 300$ ps), GaAs/AlGaAs microcavities.This is a crucial parameter for many-body theories which include the polariton-polariton interactions.It is much harder to establish this number in high-$Q$ structures compared to low-$Q$ structures, because the upper polariton is nearly invisible in high-$Q$ cavities.We present a combination of photoluminescence, photoluminescence excitation, and reflectivity measurements to highly constrain the fit model, and compare the results of this model to the results from low-$Q$ structures.We present a fitted curve of exciton fraction as a function of the lower polariton energy for multiple samples which have been used in prior experiments.

cond-mat.mes-hall↗

arXiv2023

Bose condensation of upper-branch exciton-polaritons in a transferrable microcavity

Exciton-polaritons are composite bosonic quasiparticles arising from the strong coupling of excitonic transitions and optical modes. Exciton-polaritons have triggered wide exploration in the past decades not only due to their rich quantum phenomena such as superfluidity, superconductivity and quantized vortices but also due to their potential applications for unconventional coherent light sources and all-optical control elements. Here, we report the observation of Bose-Einstein condensation of the upper polariton branch in a transferrable WS$_2$ monolayer microcavity. Near the condensation threshold, we observe a nonlinear increase in upper polariton intensity. This sharp increase in intensity is accompanied by a decrease of the linewidth and an increase of the upper polariton temporal coherence, all of which are hallmarks of Bose-Einstein condensation. By simulating the quantum Boltzmann equation, we show that the upper polariton condensation only occurs for a particular range of particle density. We can attribute the creation of Bose condensation of the upper polariton to the following requirements: 1) the upper polariton is more excitonic than the lower one; 2) there is relatively more pumping in the upper branch; and 3) the conversion time from the upper to the lower polariton branch is long compared to the lifetime of the upper polaritons.

cond-mat.quant-gas↗

arXiv2023

Coherence measurements of polaritons in thermal equilibrium reveal a power law for two-dimensional condensates

We have created a spatially homogeneous polariton condensate in thermal equilibrium, up to very high condensate fraction. Under these conditions, we have measured the coherence as a function of momentum, and determined the total coherent fraction of this boson system from very low density up to density well above the condensation transition. These measurements reveal a consistent power law for the coherent fraction as a function of the total density over nearly three orders of its magnitude. The same power law is seen in numerical simulations solving the two-dimensional Gross-Pitaevskii equation for the equilibrium coherence. This power law has not been predicted by prior analytical theories.

cond-mat.quant-gas↗

arXiv2022

Ballistic transport of a polariton ring condensate with spin precession

It is now routine to make Bose-Einstein condensates of polaritons with long enough lifetime and low enough disorder to travel ballistically for hundreds of microns in quasi-one-dimensional (1D) wires. We present observations of a polariton condensate injected at one point in a quasi-1D ring, with a well-defined initial velocity and direction. A clear precession of the circular polarization is seen, which arises from an effective spin-orbit coupling term in the Hamiltonian. Our theoretical model accurately predicts the experimentally observed behavior, and shows that "zitterbewegung" behavior plays a role in the motion of the polaritons.

cond-mat.quant-gas↗

arXiv2022

Critical fluctuations in a confined driven-dissipative quantum condensate

Phase fluctuations determine the low-energy properties of quantum condensates. However, at the condensation threshold, both density and phase fluctuations are relevant. While strong emphasis has been given to the investigation of phase fluctuations, which dominate the physics of the quantum system away from the critical point -- number fluctuations have been much less explored, even in thermal equilibrium. In this work, we report experimental observation and theoretical description of fluctuations in a circularly-confined non-equilibrium Bose-Einstein condensate of polaritons near the condensation threshold. We observe critical fluctuations, which combine the number fluctuations of a single-mode condensate state and competition between different states. The latter are analogous to mode hopping in photon lasers. Our theoretical analysis indicates that this phenomenon is of a quantum character, while classical noise of the pump is not sufficient to explain the experiments. The manifestation of a critical quantum state competition unlocks new possibilities for the study of condensate formation while linking to practical realizations in photonic lasers.

cond-mat.quant-gas↗

arXiv2021

Photoluminescence switching in a two-dimensional atomic crystal

Two-dimensional materials are an emerging class of new materials with a wide range of electrical and optical properties and potential applications. Single-layer structures of semiconducting transition metal dichalcogenides are gaining increasing attention for use in field-effect transistors. Here, we report a photoluminescence switching effect based on single-layer WSe2 transistors. Dual gates are used to tune the photoluminescence intensity. In particular, a side-gate is utilized to control the location of ions within a solid polymer electrolyte to form an electric double layer at the interface of electrolyte and WSe2 and induce a vertical electric field. Additionally, a back-gate is used to apply a 2nd vertical electric field. An on-off ratio of the light emission up to 90 was observed under constant pump light intensity. In addition, a blue shift of the photoluminescence line up to 36 meV was observed. We attribute this blue shift to the decrease of exciton binding energy due to the change of nonlinear in-plane dielectric constant and use it to determine the 3rd order off-diagonal susceptibility \c{hi}^((3) )=3.50*10^(-19)m2/V2.

cond-mat.mtrl-sci↗

arXiv2020

Observation of the Interlayer Exciton Gases in WSe$_2$ -p: WSe$_2$ Heterostructures

Interlayer excitons (IXs) possess a much longer lifetime than intralayer excitons due to the spatial separation of the electrons and holes; hence, they have been pursued to create exciton condensates for decades. The recent emergence of two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs), and of their van der Waals heterostructures (HSs), in which two different 2D materials are layered together, has created new opportunities to study IXs. Here we present the observation of IX gases within two stacked structures consisting of hBN/WSe$_2$/hBN/p: WSe$_2$/hBN. The IX energy of the two different structures differed by 82 meV due to the different thickness of the hBN spacer layer between the TMD layers. We demonstrate that the lifetime of the IXs is shortened when the temperature and the pump power increase. We attribute this nonlinear behavior to an Auger process.

cond-mat.mtrl-sci↗