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Magnetic-field-dependent quantum emission in hexagonal boron nitride at room temperature
摘要： Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system crossing transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters, promising efficient photon extraction and atom-scale engineering, but observations of spin-related effects have remained thus far elusive. Here, we report room-temperature observations of strongly anisotropic photoluminescence patterns as a function of applied magnetic field for select quantum emitters in h-BN. Field-dependent variations in the steady-state photoluminescence and photon emission statistics are consistent with a spin-dependent inter-system crossing between triplet and singlet manifolds, indicating that optically-addressable spin defects are present in h-BN.
关键词： photoluminescence,room temperature,quantum emitters,magnetic field,hexagonal boron nitride,spin defects
更新于2025-09-23 15:22:29
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Nonradiative decay and absorption rates of quantum emitters embedded in metallic systems: Microscopic description and their determination from electronic transport
摘要： We investigate nonradiative decay and absorption rates of two-level quantum emitters embedded in a metal at low temperatures. We obtain the expressions for both nonradiative transition rates and identify a unique, experimentally accessible way to obtain both nonradiative transition rates via electronic transport in the host metallic system. Our findings not only provide a microscopic description of the nonradiative channels in metals, but they also allow one to identify, determine, and differentiate them from other decay channels, which is crucial to the understanding and controlling of the light-matter interactions at the nanoscale.
关键词： nonradiative decay,metallic systems,quantum emitters,electronic transport,absorption rates
更新于2025-09-23 15:21:21
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Topological Quantum Optics Using Atomlike Emitter Arrays Coupled to Photonic Crystals
摘要： We propose an experimentally feasible nanophotonic platform for exploring many-body physics in topological quantum optics. Our system is composed of a two-dimensional lattice of nonlinear quantum emitters with optical transitions embedded in a photonic crystal slab. The emitters interact through the guided modes of the photonic crystal, and a uniform magnetic field gives rise to large topological band gaps, robust edge states, and a nearly flat band with a nonzero Chern number. The presence of a topologically nontrivial nearly flat band paves the way for the realization of fractional quantum Hall states and fractional topological insulators in a topological quantum optical setting.
关键词： Chern number,quantum emitters,fractional quantum Hall states,photonic crystals,topological quantum optics
更新于2025-09-23 15:21:01
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Conceptual Implementation of a Photonica??Plasmonic Transistor into a Structured Nanoa??Guided Hybrid System
摘要： The interplay between quantum emitters and plasmonic nanostructures can unlock unprecedented functionalities, potentially useful for novel-concept photonics. In this work, the design and conceptual implementation of an integrated photonic-plasmonic transistor is reported. A mixed top-down and bottom-up nanofabrication approach has been used to realize a prototype based on a nano-guided hybrid system enabling the interaction between Au nanostructures and emitters and thus resulting in a plasmon-exciton exchange. In analogy with a classical transistor (MOSFET), Au nanotapers have been fabricated in specific positions on a waveguide to behave as drain, source and gate for highly localized electric near-fields. Photopolymerization by evanescent waves has been then exploited to grow a polymeric ridge containing quantum dots directly on top of the nanotapers. The fluorescent spectrometry of the prototype evidences a sensitive Purcell enhancement of the emission of the quantum dots located in proximity of the apices of Au nanotapers. The numerical study of the hybrid system demonstrates how this enhancement is controlled to efficiently route and modulate high frequency optical signals in the novel photonic device.
关键词： quantum emitters,Plasmonics,Transistor,Photonics
更新于2025-09-23 15:21:01
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All-photonic quantum teleportation using on-demand solid-state quantum emitters
摘要： All-optical quantum teleportation lies at the heart of quantum communication science and technology. This quantum phenomenon is built up around the nonlocal properties of entangled states of light that, in the perspective of real-life applications, should be encoded on photon pairs generated on demand. Despite recent advances, however, the exploitation of deterministic quantum light sources in push-button quantum teleportation schemes remains a major open challenge. Here, we perform an important step toward this goal and show that photon pairs generated on demand by a GaAs quantum dot can be used to implement a teleportation protocol whose fidelity violates the classical limit (by more than 5 SDs) for arbitrary input states. Moreover, we develop a theoretical framework that matches the experimental observations and that defines the degree of entanglement and indistinguishability needed to overcome the classical limit independently of the input state. Our results emphasize that on-demand solid-state quantum emitters are one of the most promising candidates to realize deterministic quantum teleportation in practical quantum networks.
关键词： GaAs quantum dot,entangled photon pairs,quantum emitters,quantum teleportation,quantum communication
更新于2025-09-23 15:19:57
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Collectively induced exceptional points of quantum emitters coupled to nanoparticle surface plasmons
摘要： Exceptional points, resulting from non-Hermitian degeneracies, have the potential to enhance the capabilities of quantum sensing. Thus, finding exceptional points in different quantum systems is vital for developing such future sensing devices. Taking advantage of the enhanced light-matter interactions in a confined volume on a metal nanoparticle surface, here we theoretically demonstrate the existence of exceptional points in a system consisting of quantum emitters coupled to a metal nanoparticle of subwavelength scale. By using an analytical quantum electrodynamics approach, exceptional points are manifested as a result of a strong-coupling effect and observable in a drastic splitting of originally coalescent eigenenergies. Furthermore, we show that exceptional points can also occur when a number of quantum emitters are collectively coupled to the dipole mode of localized surface plasmons. Such a quantum collective effect not only relaxes the strong-coupling requirement for an individual emitter, but also results in a more stable generation of the exceptional points. Furthermore, we point out that the exceptional points can be explicitly revealed in the power spectra. A generalized signal-to-noise ratio, accounting for both the frequency splitting in the power spectrum and the system’s dissipation, shows clearly that a collection of quantum emitters coupled to a nanoparticle provides a better performance of detecting exceptional points, compared to that of a single quantum emitter.
关键词： strong-coupling effect,metal nanoparticle,power spectra,quantum emitters,quantum sensing,signal-to-noise ratio,surface plasmons,Exceptional points
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Fabrication of High Quality Quantum Emitters in Diamond Nanostructures
摘要： As the field of solid-state quantum engineering matures, it is increasingly necessary to produce quantum emitters with narrow optical transitions and long spin coherence times aligned to nanophotonic structures. The nitrogen-vacancy (NV) defect center in diamond is a well-suited candidate owing to a spin ground state with a long coherence time, nearby nuclear spins for quantum memories, and spin-selective optical transitions allowing for efficient optical spin initialization and readout. We demonstrate an emitter-device alignment technique enabling fabrication of photonic devices registered to NVs. The alignment method relies on autonomously imaging emitters and registering them relative to an on-chip coordinate system. This technique can be performed on a large variety of emitters. The repeatability of this method suggests a spatial accuracy of 50 nm. The ability to navigate a sample autonomously facilitates data collection on a large number of NVs, thus permitting statistical analyses. We utilized this approach to correlate the NV’s host nitrogen isotope with the optical linewidth of the emitter to understand the effects of implantation. As shown in Fig. 1a, the data indicate that the coherent, narrow-linewidth NVs are formed from naturally abundant nitrogen (14N), whereas the implanted nitrogens (15N), on average, yield broader linewidth NVs. The implanted 15NVs also exhibit larger axial and transverse strains suggesting that damage was produced near the emitter. We attribute the broad linewidths of implanted 15NVs to a more volatile local environment generated by local damage resulting from the ion implantation process.
关键词： diamond nanostructures,nanophotonic structures,nitrogen-vacancy center,spin coherence,quantum emitters
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Coherent Coupling of Single Molecules to Microresonators
摘要： Many interesting proposals in quantum optics and light-matter interaction rely on having multiple quantum emitters well-coupled to a single mode of light. Of particular interest are cases where several identical emitters couple to a one-dimensional (1D) photonic medium. Recently, we presented such a system by evanescent coupling of organic dye molecules to the same guided mode of an on-chip subwavelength waveguide [1]. While this coupling allowed us to demonstrate up to 7.5% transmission extinction of the propagating light by a single molecule, it is still not sufficient for achieving higher-order effects such as photon-mediated interaction of multiple emitters coupled to the same waveguide. One way to improve the waveguide-emitter coupling is the use of resonant structures, as was recently shown in our laboratory for a microscopic open Fabry-Perot cavity [2]. In that work, we demonstrated a strong Purcell broadening of the molecular emission, and almost complete extinction of the resonant cavity transmission. In the current work, we extended this approach to on-chip racetrack resonators [3], as shown in Fig. 1(a). In such a geometry, the coupling enhancement is proportional to the number of photon round trips inside the resonator, which is roughly equal to F/π, where F is the resonator finesse. Currently, our resonators can reach finesse as high as 18 when exposed to the surrounding organic matrix at cryogenic temperatures, leading to enhanced extinction dips up to 22%, as shown in the orange plot in Fig. 1(b). We additionally verify the molecule-resonator coupling by localizing the position of the molecule (marked by a white arrow in Fig. 1(a)), and by observing the expected peak in the transmission port of the resonator (blue line in Fig. 1(b)). Finally, we perform a comparison to a single waveguide on the same chip, which still showed maximal extinction of only 7%, consistent with the previous results. We discuss the observed degree of enhancement, compare it with the predictions of theoretical calculations, and evaluate future strategies for reaching on-chip near-unity coupling efficiency as well as many-emitter effects, such as light localization and generation of polaritonic states [4].
关键词： racetrack resonators,light-matter interaction,waveguide-emitter coupling,photonic medium,quantum optics,Purcell broadening,polaritonic states,resonant structures,Fabry-Perot cavity,quantum emitters
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Deterministic Integration of Quantum Dots into On-Chip Multi-Mode Interference Couplers Via in-Situ Electron Beam Lithography
摘要： On-chip quantum optical circuits offer superior performance and scalability compared to bulky optical setups. Additionally, the up-scaling of quantum systems will foster the realization of photonic quantum computers to outperform their classical counterparts. In this context, the deterministic integration of quantum emitters into on-chip photonic elements is crucial for the implementation of scalable on-chip quantum circuits. Recent activities in this field include hybrid QD-waveguides for enhanced photon in-coupling [1] and first, rather tedious steps towards the controlled integration of QDs using multistep-lithography [2] as well as AFM tip transfer [3]. Here we report on the deterministic integration of single quantum dots (QD) into on-chip beam splitters using in-situ electron beam lithography (EBL) [4]. In this single-step technique, photonic building blocks are patterned by means of EBL on top of chosen QDs immediately after spatially and spectrally pre-characterizing QDs by means of cathodoluminescence mapping at cryogenic temperatures (~10 K) [5]. The used in-situ EBL technology platform allows for the realization of complex on-chip quantum circuits with high process yield (see Fig. 1(a-d)). To underline the high potential of this method we realize 50/50 coupling elements connected to waveguide sections with deterministically integrated QDs (see Fig. 1(e)). The couplers act as central building blocks of on-chip quantum circuits and we chose a robust design based on tapered multimode interference (MMI) splitters which feature relaxed fabrication tolerances and a constant 50/50 splitting ratio. We demonstrate the functionality of the deterministic QD-waveguide structures by high-resolution μPL spectroscopy and by studying the photon cross-correlation between the two MMI output ports (Port 1 and Port 2 in Fig. 1(e)). The latter confirms single-photon emission and on-chip splitting associated with g(2)(0) < 0.5. Present work focusses on the deterministic realization of heterogeneous integrated quantum photonic devices and multi-QD quantum circuits allowing for on-chip Hong-Ou-Mandel experiments.
关键词： on-chip quantum circuits,quantum dots,photonic quantum computers,electron beam lithography,quantum emitters
更新于2025-09-11 14:15:04
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Superior properties in room-temperature colloidal-dot quantum emitters revealed by ultralow-dark-count detections of temporally-purified single photons
摘要： The realization of high-quality quantum emitters that can operate at room temperature is important for accelerating the application of quantum technologies, such as quantum communication, quantum information processing, and quantum metrology. In this work, we study the photon-antibunching properties on room-temperature emission from individual colloidal quantum dots (CQDs) using superconducting-nanowire single-photon detectors and temporal filtering of the photoluminescence decay curve. We find that high single-photon purities and high photon-generation rates can be simultaneously achieved by removing the signals originating from the sequential two-photon emission of biexcitons created by multiple excitation pulses. We successfully demonstrate that the ultrahigh performance of the room-temperature single-photon sources showing g(2)(0) ? 10?2 can be confirmed by the ultralow-dark-count detection of the temporally purified single photons. These findings provide strong evidence for the attractiveness of CQDs as candidates for high-quality room-temperature quantum light sources.
关键词： single-photon sources,room-temperature,superconducting-nanowire single-photon detectors,quantum emitters,colloidal quantum dots,temporal filtering
更新于2025-09-11 14:15:04