The ARTEMIS project aims to develop integrable quantum sources based on metal-organic compounds with transition metal and/or lanthanide ions. These materials exhibit tunable linear emission and nonlinear optical properties, enabling on-demand generation of single photons and entangled photon pairs or triplets. When integrated with plasmonic supernanostructured cavities, these molecular emitters achieve strong optical enhancement. Our group focuses on the quantum characterisation of the light emitted by these sources to explore their potential for new metrology and sensing applications in the quantum regime. Spectroscopic and time-resolved measurements on newly synthesized compounds Tb N(Bzlm)3 and Eu N(Bzlm)3 dissolved in DMSO at high concentration reveal narrow emission bands and relatively long decay times.
The ARTEMIS project aims to develop integrable quantum sources based on metal-organic compounds with transition metal and/or lanthanide ions. These materials exhibit tunable linear emission and nonlinear optical properties, enabling on-demand generation of single photons and entangled photon pairs or triplets. When integrated with plasmonic supernanostructured cavities, these molecular emitters achieve strong optical enhancement. Our group focuses on the quantum characterisation of the light emitted by these sources to explore their potential for new metrology and sensing applications in the quantum regime. Spectroscopic and time-resolved measurements on newly synthesized compounds Tb N(Bzlm)3 and Eu N(Bzlm)3 dissolved in DMSO at high concentration reveal narrow emission bands and relatively long decay times.
Our group recently discovered bright, stable, linearly polarized, and high-purity sources of single-photon emission at room temperature in SiN. Currently, we study the possibility of generating indistinguishable photons by plasmonic speed-up of photoemission, which may enable broader applications of SiN single-photon sources in quantum information technology. The enhancement of the light-matter interaction with plasmonic materials can shorten the spontaneous emission time to beat the dephasing time and achieve coherence even at non-cryogenic temperatures. Our findings spark further studies of quantum emitters toward deeper understanding of their nature, deterministic formation, and scalable integration with on-chip quantum photonic circuitry.
The capability of realizing quantum photonics implementations on-chip will have a strong impact on several aspects of quantum computation and information processing. The implementation of large scale integrated quantum photonic technologies requires on-chip reconfigurable waveguide circuits as well as single-photon sources and detectors. Many successes have been made in recent years to demonstrate complex quantum circuits in many material platforms. Among all these platforms, the Silicon-on-Insulator (SOI) platform is outstanding as it is well developed for classical applications and therefore deploys a high component density, mature fabrication techniques and compatibility with the telecom regime and the complementary metal-oxide-semiconductor (CMOS) technology. However, the lack of on-demand non-classical light sources, directly incorporated in silicon chips, forces the use of nonlinear processes to generate non-classical light states: the probabilistic nature of the emission process sets a limit in the maximally achievable experimental complexity. The use of on-demand sources will have a strong impact on the device’s scalability.
Summary form only given. A current challenge and trend in optical sciences is to extend the toolbox generated from experiments with single emitters and single photons towards interfacing photons with a well-defined number of quantum emitters. The resulting complex optical network would enable studies of many-body quantum optical phenomena and could lend itself to quantum simulations. However, common light-matter interfaces via strong focusing or cavity enhancement do not scale favourably. Therefore, achieving many-body coupling while preserving control of the individual quantum systems poses remarkable experimental challenges.Here, we present an inherently scalable platform, which relies on the evanescent coupling of single dye molecules to subwavelength TiO2waveguides (nanoguides) that are embedded in an organic matrix (Fig. 1a). At liquid helium temperatures, we observe lifetime-limited linewidths for these molecules distributed over an inhomogeneously broadened spectrum. However, by using integrated microelectrodes, we can Stark shift the resonances over a large bandwidth. The dopant concentration determines the optical density of our system which can reach up to a few hundred molecules per cubic wavelength. The highly confined mode of a nanoguide allows a substantial mode overlap with the emission pattern of a single emitter, resulting in coupling efficiencies of up to 32%. Therefore, we can observe coherent extinction signals from many different molecules in the transmission signal of a nanoguide; an example is shown by the blue curve in Fig. 1b [1]. The green and red curves in Fig. 1b demonstrate the nonlinear behaviour of a molecule when driven with a second narrow-band laser [1, 2]. We show that by modifying the spectral properties of the molecules either via external optical or static electric fields we control the optical response of a nanoguide. In addition to discussing subtleties of design and fabrication, we elaborate on future efforts towards the realization of on-chip polaritonic states [3] and the integration of further optical elements such as micoresonators [4].
Quantum photonics provides a powerful toolbox with vast applications ranging from quantum simulation, photonic information processing, all optical universal quantum computation, secure quantum internet as well as quantum enhanced sensing. Many of these applications require the integration of several complex optical elements and material systems which pose a challenge to scalability. It is essential to integrate linear and non-linear photonics on a chip to tackle this issue leading to more compact, high bandwidth devices. In this thesis we demonstrate a pathway to achieving several components in the quantum photonic toolbox on the same integrated photonic platform. We focus particularly on two of the more nontrivial components, a single photon source and an integrated quantum light-matter interface. We address the problem of a scalable, chip integrated, fast single photon source, by using atomically thin layers of 2D materials interfaced with plasmonic waveguides. We further embark on the challenge of creating a new material system by integrating rare earth ions with the emerging commercial platform of thin film lithium niobate on insulator. Rare earth ions have found widespread use in classical and quantum information processing. However, these are traditionally doped in bulk crystals which hinder their scalability. We demonstrate an integrated photonic interface for rare earth ions in thin film lithium niobate that preserves the optical and coherence properties of the ions. This combination of rare earth ions with the chip-scale active interface of thin film lithium niobate opens a plethora of opportunities for compact optoelectronic devices. As an immediate application we demonstrate an integrated optical quantum memory with a rare earth atomic ensemble in the thin film. The new light matter interface in thin film lithium niobate acts as a key enabler in an already rich optical platform representing a significant advancement in the field of integrated quantum photonics.
Single organic molecules make excellent single photon sources, emitting photons with high efficiency and at favourable wavelengths for coupling to other quantum systems, including alkali atoms. I will discuss techniques to create organic crystals containing single photon emitting molecules, and our recent results applying strain to these crystals to tune their emission wavelength. I will show that subsequent photons emitted by a single molecule can undergo quantum interference at a beam splitter, a vital tool in optical quantum computing and communication, and will discuss how discuss how to assess photon indistinguishability using both continuous and pulsed lasers. While molecular excitation and radiative emission is efficient, generated photons can be difficult to collect without the use of photonic structures. I will discuss our recent efforts in coupling single molecules to waveguides and nanophotonic cavities.
Over the past two decades, rapid progress in the development of quantum light sources has positioned quantum optics as a cornerstone of emerging quantum technologies. This thesis presents two entirely new and distinct advances in quantum optics, each introducing quantum light sources into unconventional environments. In the first part, nanoparticles of hexagonal boron nitride (hBN) with optically active color centers were successfully introduced into living cells, where they emitted light in the form of temporally isolated single photons. Unlike conventional light sources, each color center emits exactly one photon at a time — a fundamentally quantum mechanical phenomenon with no classical analogue. The emitters showed excellent single-photon purity, outstanding emission stability with no photobleaching or spectral drift over several hours, and negligible impact on cell health. Crucially, because different color centers emit at different wavelengths and with distinct spectral profiles, they can serve as unique optical fingerprints. Combining just a few per cell allows virtually unlimited numbers of cells to be uniquely tagged. Beyond labeling, the single-photon nature of these emitters opens a path toward quantum-limited sensing and imaging inside living tissue. In addition to single-photon emitters, we also investigated sources of entangled photon pairs. These have traditionally relied on solid-state nonlinear crystals, which are rigid, difficult to tune, and offer little flexibility once fabricated. To overcome these limitations, we turn to soft matter: we developed and investigated sources based on ferroelectric nematic liquid crystals (FNLCs), a newly discovered class of organic materials with exceptionally strong intrinsic electric polarization and optical nonlinearity, as a platform for generating entangled photon pairs through spontaneous parametric down-conversion (SPDC). The results presented here mark the first demonstration of photon-pair generation in organic matter via SPDC. By reorienting the liquid crystal molecules through sample geometry or applied electric fields, the intensity, polarization state, and degree of entanglement of the generated photon pairs can all be controlled — a level of tunability not available in conventional solid-state sources. Additionally, chiral FNLCs with a self-assembled helical structure were shown to produce photon-pair generation rates comparable to or exceeding those of the best solid-state platforms. By introducing scalable, efficient, and reconfigurable quantum light sources with functionalities beyond those of conventional solid-state platforms, this work opens new directions in quantum optics and related technologies.