arXiv subjects

Adam Olejniczak

Publications and source records attributed to Adam Olejniczak.

5 recordsLinked to original sources

arXiv2026

When Blinking Helps: Suppressed Biexciton Emission in Lead Halide Perovskite Quantum Dots

Blinking and multiphoton emission in metal halide perovskite quantum dots (PQDs) limit their use as single-photon quantum emitters. Conventional models distinguish between trion-related A-type blinking and defect-assisted BC-type blinking, both expected to degrade single-photon purity in a dark state. Here, time-resolved spectroscopy on individual PQDs reveals a qualitatively different regime in which low emitting dark states exhibit higher single-photon purity than bright states. For those PQDs state-resolved $g^{(2)}(\tau)$ analysis shows that the exciton photoluminescence quantum yield decreases by a factor of $\sim 8$, while the biexciton one is suppressed by a factor of $\sim 10$. This leads to a moderate improvement of single-photon purity with $g^{(2)}_0$ decreased from 0.155 to 0.120. In contrast, PQDs with fluorescence lifetime--intensity distribution patterns characteristic for A-type blinking, display the expected increase of $g^{(2)}_0$ in charged, trion-dominated states. To explain the observed improvement of single-photon purity of low-emitting dark states, we propose a self-trapped-exciton (STE) mechanism that selectively blocks biexciton formation by diverting hot excitons into long-lived, weakly emissive STE configurations. This STE-mediated blinking channel explains why certain low-emitting states improve, rather than degrade, single-photon purity and suggests a lattice-driven route to perovskite quantum emitters with intrinsically suppressed multiphoton events.

cond-mat.mes-hall↗

arXiv2025

Perovskite Nanocrystals as Emerging Single-Photon Emitters: Progress, Challenges, and Opportunities

Metal-halide perovskite nanocrystals (PNCs) have emerged as leading candidates for next-generation quantum emitters, offering a unique combination of high photoluminescence quantum yield, tunable emission, short radiative lifetimes, and record-high single-photon purity under ambient conditions. These properties, together with low-cost and scalable solution-phase fabrication, position PNCs as attractive alternatives to traditional epitaxial and colloidal quantum dots. In this Review, we outline the physical parameters that define quantum emission in PNCs, compare their performance to other established and emerging quantum emitters, and assess the key figures of merit, including photostability, single-photon purity, and photon indistinguishability, required for practical quantum applications. We discuss underlying mechanisms affecting PNC emission behavior and highlight recent advances in improving their quantum emitting properties through synthetic and photonic engineering approaches. While challenges related to environmental stability and photon indistinguishability remain, emerging strategies, such as surface passivation, metal ion doping, and coupling with electromagnetic nano- and micro-cavities, are steadily closing the gap between PNCs and ideal quantum light sources.

physics.optics↗

arXiv2025

Nickel Doping Unlocks Ambient-condition Photostability in Individual Cesium Lead Bromide Perovskite Quantum Dots

Developing efficient single-photon sources is fundamental to advancing photonic quantum technologies. In particular, achieving scalable, cost-effective, stable, high-rate, and high-purity single-photon emission at ambient conditions is paramount for free-space quantum communication. However, fulfilling all the requirements simultaneously under ambient conditions has remained a significant challenge. Here, the scalable, cost-effective ambient condition synthesis of nickel doped (Ni doped) CsPbBr3 perovskite quantum dots (NPQDs) is presented using a modified ligand-assisted reprecipitation (LARP) method. The resulting individual NPQDs demonstrate remarkable photostability, sustaining their performance for over 10 minutes under ambient conditions with environment humidity of ~55%, and exhibit exceptional single-photon purity (>99%) with a narrow emission linewidth (~70 meV). The remarkable photostability could be attributed to the spatial localization of exciton by Ni atoms on the surface of the nanocrystal, reducing its interaction with the environment. Our results demonstrated that NPQDs with outstanding combinations of quantum emitting properties can be both synthesized and operated at ambient conditions. These findings mark a significant step toward scalable, cost-effective quantum light sources for real-world applications, paving the way for robust quantum communication systems and devices.

cond-mat.mtrl-sci↗

arXiv2024

Advancements and challenges in plasmon-exciton quantum emitters based on colloidal quantum dots

The Nobel Prizes in Physics (2022) and Chemistry (2023) heralded the recognition of quantum information science and the synthesis of quantum dots, respectively. This acknowledgment has propelled colloidal quantum dots and perovskite nanocrystals to the forefront of quantum technologies. Their distinct emission properties, facilitating the efficient generation of both single photons and photon pairs, render them particularly captivating. Moreover, their adaptability to diverse structures, ranging from traditional electronics to nanopatterned frameworks, underscores their pivotal role in shaping quantum technologies. Despite notable strides in synthesis, certain properties require refinement for enhanced applicability in quantum information, encompassing emission brightness, stability, single photon indistinguishability, and entanglement fidelity of photon pairs. Here we offer an overview of recent achievements in plasmon-exciton quantum emitters based on luminescent semiconductor nanocrystals. Emphasizing the utilization of the light-matter coupling phenomenon, we explore how this interaction enables the manipulation of quantum properties without altering the chemical structure of the emitters. This approach addresses critical aspects for quantum information applications, offering precise control over emission rate, intensity, and energy. The development of these hybrid systems represents a significant stride forward, demonstrating their potential to overcome existing challenges and advance the integration of quantum emitters into cutting-edge quantum technology applications.

cond-mat.mes-hall↗

arXiv2023

On-demand reversible switching of the emission mode of individual semiconductor quantum emitters using plasmonic metasurfaces

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications as quantum information, quantum communication and quantum cybersecurity. The central building block for these applications is a quantum emitter (QE), a controllable source of single photons or photon pairs. Semiconductor QEs such as perovskite nanocrystals (PNCs) and semiconductor quantum dots (QDs) have been demonstrated to be a promising material for pure single-photon emission, and their hybrids with plasmonic nanocavities may serve as sources of photon pairs. Here we have designed a system in which individual quantum emitters and their ensembles can be traced before, during, and after the interaction with the external plasmonic metasurface in controllable way. Upon coupling the external plasmonic metasurface to the array of QEs, the individual QEs switch from single-photon to photon-pair emission mode. Remarkably, this method does not affect the chemical structure and composition of the QEs, allowing them to return to their initial state after decoupling from the plasmonic metasurface. By employing this approach, we have successfully demonstrated the reversible switching of the ensemble of individual semiconductor QEs between single-photon and photon pair emission modes. This significantly broadens the potential applications of semiconductor QEs in quantum technologies.

physics.optics↗