L'electrodynamique quantique en cavite (EDQC) etudie l'interaction matiere rayonnement a son niveau le plus fondamental, ie lorque la matiere est bien decrite par un systeme a deux niveaux, et la lumiere par un mode unique du champ electromagnetique. Les premiers eets d'EDQC ont ete observes dans le debut des annees 80 pour des systemes de physique atomique. Avec le developpement des techniques de micro et nano-fabrication, l'eet Purcell, puis le couplage fort, ont egalement pu etre observes pour des atomes articiels couples a des cavites semiconductrices. Ces systemes presentent les avantages d'etre potentiellement integrables sur un circuit et realisables a grande echelle. Dans ce contexte, les boites quantiques semiconductrices (BQ) sont des candidats particulierement prometteurs. Cependant, a cause de la presence d'une matrice environnante, source intrinseque de decoherence, ces systemes s'ecartent du paradigme de la physique atomique. Dans le cas des BQs en particulier, ce couplage peut etre important et modier les observations de maniere singuliere. On se propose ici d'etudier la mesure du facteur de Purcell, qui est un des facteurs de me- rite de l'EDQC, pour une BQ dans une cavite de type micropilier. Dierentes approches seront presentees et comparees entre elles, qui tiennent compte de la specicite des BQ, et montrent que l'utilisation d'un modele plus n est necessaire pour interpreter les resultats obtenus. En- n, le dernier chapitre est consacre a une application interessante de ce type de systeme, qui consiste a utiliser la saturation de la boite quantique pour realiser une non-linearite optique a l'echelle du photon unique.
Nitrogen-Vacancy centers in diamond possess an electronic spin resonance that strongly depends on temperature, which makes them efficient temperature sensor with a sensitivity down to a few mK/$\sqrt{\rm Hz}$. However, the high thermal conductivity of the host diamond may strongly damp any temperature variations, leading to invasive measurements when probing local temperature distributions. In view of determining possible and optimal configurations for diamond-based wide-field thermal imaging, we here investigate, both experimentally and numerically, the effect of the presence of diamond on microscale temperature distributions. Three geometrical configurations are studied: a bulk diamond substrate, a thin diamond layer bonded on quartz and diamond nanoparticles dispersed on quartz. We show that the use of bulk diamond substrates for thermal imaging is highly invasive, in the sense that it prevents any substantial temperature increase. Conversely, thin diamond layers partly solve this issue and could provide a possible alternative for microscale thermal imaging. Dispersions of diamond nanoparticles throughout the sample appear as the most relevant approach as they do not affect the temperature distribution, although NV centers in nanodiamonds yield lower temperature sensitivities compared to bulk diamond.
Nitrogen-vacancy centers in diamonds possess an electronic spin resonance that strongly depends on temperature, which makes them efficient temperature sensors with sensitivity down to a few mK/Hz. However, the high thermal conductivity of the host diamond may strongly damp any temperature variations, leading to invasive measurements when probing local temperature distributions. In the view of determining possible and optimal configurations for diamond-based wide-field thermal imaging, here, we investigate both experimentally and numerically the effect of the presence of diamonds on microscale temperature distributions. Three geometrical configurations are studied: a bulk diamond substrate, a thin diamond layer bonded on quartz, and diamond nanoparticles dispersed on quartz. We show that the use of bulk diamond substrates for thermal imaging is highly invasive in the sense that it prevents any substantial temperature increase. Conversely, thin diamond layers partly solve this issue and could provide a possible alternative for microscale thermal imaging. Dispersions of diamond nanoparticles throughout the sample appear as the most relevant approach as they do not affect the temperature distribution, although NV centers in nanodiamonds yield lower temperature sensitivities than bulk diamonds.
Photonic information processing requires giant optical non-linearities to implement logic gates between photons and optical switches at the single photon level. A very promising non-linear medium is a "one dimensional atom", that is a directional high-finesse cavity containing a resonant two-level system in the Purcell regime. We aim at experimentally demonstrating this effect using a single quantum dot in a symmetric micropillar, the directionality of the micropillar ensuring the one-dimensionality of the problem.
Abstract Magnetic random access memory (MRAM) is a leading emergent memory technology that is poised to replace current non-volatile memory technologies such as eFlash. However, controlling and improving distributions of device properties becomes a key enabler of new applications at this stage of technology development. Here, we introduce a non-contact metrology technique deploying scanning NV magnetometry (SNVM) to investigate MRAM performance at the individual bit level. We demonstrate magnetic reversal characterization in individual, <60 nm-sized bits, to extract key magnetic properties, thermal stability, and switching statistics, and thereby gauge bit-to-bit uniformity. We showcase the performance of our method by benchmarking two distinct bit etching processes immediately after pattern formation. In contrast to ensemble averaging methods such as perpendicular magneto-optical Kerr effect, we show that it is possible to identify out of distribution (tail-bits) bits that seem associated to the edges of the array, enabling failure analysis of tail bits. Our findings highlight the potential of nanoscale quantum sensing of MRAM devices for early-stage screening in the processing line, paving the way for future incorporation of this nanoscale characterization tool in the semiconductor industry.
Efficient coupling between a localized quantum emitter and a well defined optical channel represents a powerful route to realize single-photon sources and spin-photon interfaces. The tailored fiber-like photonic nanowire embedding a single quantum dot has recently demonstrated an appealing potential. However, the device requires a delicate, sharp needle-like taper with performance sensitive to minute geometrical details. To overcome this limitation we demonstrate the photonic trumpet, exploiting an opposite tapering strategy. The trumpet features a strongly Gaussian far-field emission. A first implementation of this strategy has lead to an ultra-bright single-photon source with a first-lens external efficiency of 0.75 ± 0.1 and a predicted coupling to a Gaussian beam of 0.61 ± 0.08.
Efficient coupling between a localized quantum emitter and a well defined optical channel represents a powerful route to realize single-photon sources and spin-photon interfaces. The tailored fiber-like photonic nanowire embedding a single quantum dot has recently demonstrated an appealing potential. However, the device requires a delicate, sharp needle-like taper with performance sensitive to minute geometrical details. To overcome this limitation we demonstrate the photonic trumpet, exploiting an opposite tapering strategy. The trumpet features a strongly Gaussian far-field emission. A first implementation of this strategy has lead to an ultra-bright single-photon source with a first-lens external efficiency of 0.75 ± 0.1 and a predicted coupling to a Gaussian beam of 0.61 ± 0.08.
