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We performed microwave spectroscopy of an InAs nanowire between superconducting contacts implementing a finite-length, multi-channel Josephson weak link. Certain features in the spectra, such as the splitting by spin-orbit interactions of the transition lines among Andreev states, have been already understood in terms of non-interacting models. However, we identify here additional transitions, which evidence the presence of Coulomb interactions. By combining experimental measurements and model calculations, we reach a qualitative understanding of these very rich Andreev spectra., Comment: (6+8) pages, (4+10) figures; added figure in SM

We present a superconductor-semiconductor materials system that is both scalable and monolithically integrated on a silicon substrate. It uses selective-area growth of $\mathrm{Al}$-$\mathrm{In}\mathrm{As}$ hybrid structures on a planar III-V buffer layer, grown directly on a high-resistivity silicon substrate. We characterize the electrical properties of this materials system at millikelvin temperatures and observe a high average field-effect mobility of $\ensuremath{\mu}\ensuremath{\approx}3200\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{2}\mathrm{/Vs}$ for the $\mathrm{In}\mathrm{As}$ channel and a hard induced superconducting gap. Josephson junctions exhibit a high interface transmission, $\mathcal{T}\ensuremath{\approx}0.75$, a gate-voltage-tunable switching current with a product of critical current and normal state resistance, ${I}_{C}{R}_{N}\ensuremath{\approx}83\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{V}$, and signatures of multiple Andreev reflections. These results pave the way for scalable and high-coherence gate-voltage-tunable transmon devices and other superconductor-semiconductor hybrids fabricated directly on silicon.

The paper describes a digital low-frequency ac voltage source with amplitude stability better than 10⁻⁶ V/V per hour. It was developed to be used as a transfer standard for calibrations with ac Josephson systems and fast synchronous ac-dc transfer measurements. Its low-distortion and superb phase adjustment resolution makes it suitable for impedance measurements as well., Conference on Precision Electromagnetic Measurements (CPEM 2020), August 24-28, 2020, Denver, Colorado [Held Virtually]

A gas junction In superconductors, electrons form a macroscopic wave function that has a definite phase. If two superconductors with different wave function phases are placed in contact with each other through an insulating link, a current will flow through this so-called Josephson's junction without any external voltage. Luick et al. and Kwon et al. observed an analogous phenomenon in a setup that involved two reservoirs of superfluid Fermi gases. Both groups measured the so-called current-phase relation: the dependence of the magnitude of the current on the relative phase. By tuning an external magnetic field, they were able to study how the interactions between fermions affected the nature of the superfluid state. Science , this issue p. 89 , p. 84

En esta tesis se aborda la dinámica de un condensado de Bose-Einstein confinado en una red óptica con simetría de anillo. Trabajamos con un modelo multimodal efectivo en 3D que corrige inconvenientes de los modelos previos para este tipo de configuraciones, como la subestimación de los períodos de oscilación y el desbalance poblacional crítico que separa los regímenes de Josephson y auto-atrapado cuántico. Mediante simulaciones 3D de la ecuación de Gross-Pitaevskii confirmamos estas mejoras en distintas trampas. En primera instancia, en esta tesis se profundiza en la dinámica de un condensado confinado en un doble pozo. Se encuentra un expresión integral cerrada del período de oscilación válida para ambos regímenes y que contiene todos los parámetros presentes del modelo. Para configuraciones más complejas con mayor número de pozos, se encuentra una manera práctica de ordenar los diversos regímenes presentes cuando el número de pozos es par y se analizan los tiempos característicos cuando las órbitas no son periódicas. Se investiga la dinámica particular de estados no estacionarios con número de ocupación constante en el tiempo y fases no triviales. Por último, formulamos un modelo multimodal efectivo aplicable a condensados confinados en trampas rotantes. En este caso los parámetros de salto son números complejos. Encontramos un vínculo entre el perfil del campo de velocidades inducido y la forma de la densidad de los condensados. En particular cuando esta última tiene simetría circular, el campo de velocidades es homogéneo y establecemos una relación analítica entre la fase de Peierls de los parámetros de salto y el momento angular del estado fundamental. In this thesis the dynamics of a Bose-Einstein condensate confined in a optical lattice with ring symmetry is addressed. We work with an effective multimode model in 3D that corrects drawbacks of previous models for this type of configuration, such as underestimated oscillation periods and critical imbalances that separates the Josephson and self-trapping regimes. Through 3D Gross-Pitaevskii simulations we confirm these improvements for several traps. In the first part of the thesis, the dynamics of a condensate confined in two wells is reviewed. It is found a closed integral expression for the oscillation periods valid for both regimes and that contains all the parameters present in the model. For more complex configurations with higher number of wells, we find a practical way of ordering the various regimes when the number of wells is even. The characteristic times of the non periodic orbits are analyzed. The dynamics of particular non stationary states with fixed occupation number and non trivial phases is later investigated. Finally, we formulate an effective multimode model for rotating traps where the hopping parameters become complex numbers. We find a link between the induced velocity field and the condensate density. In particular, when the later has circular symmetry, the velocity field is homogeneous and we establish an analytical relation between the Peierls phase of the hopping parameters and the ground state angular moment. Fil: Nigro, Mauro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

In this paper, we demonstrate that the hybrid normal-superconducting-normal (NSN) structure has potential for a multifunctional thermal device which could serve for heat flux control and cooling of microstructures. By adopting the scattering matrix approach, we theoretically investigate thermal and electrical effects emerging in such structures due to the Cooper pair splitting (CPS) and elastic cotunneling phenomena. We show that a finite superconductor can, in principle, mediate heat flow between normal leads, and we further clarify special cases when this seems contradictory to the second law of thermodynamics. Among other things, we demonstrate that the CPS phenomenon can appear even in the simple case of a ballistic NSN structure., Comment: 10 pages, 5 figures

We present a single-electron device for the manipulation of charge states via quantum interference in nanostructured electrodes. Via self-inductance effects, we induce two independent magnetic fluxes in the electrodes and we demonstrate sensitivity to single charge states and magnetic field at variable temperature. Moreover, our approach allows us to demonstrate local and independent control of the single-particle conductance between nano-engineered tunnel junctions in a fully-Superconducting Quantum Interference Single-Electron Transistor (SQUISET), thereby increasing the flexibility of our single-electron transistors. Our devices show a robust modulation of the current-to-flux transfer function via control currents, while exploiting the single-electron filling of a mesoscopic superconducting island. Further applications of the device concept to single-charge manipulation and magnetic-flux sensing are also discussed., Comment: 7 pages, 4 figures

Josephson junctions are the building blocks of superconducting electronics. They are made of two superconductors separated by an insulating barrier. In this thesis, we present two experiments where the insulating barrier is replaced by a semiconductor.In the first one, we study nanowires in the regime of Coulomb blockade, where the number of electrons can be controlled, one by one, until a metal-insulator transition is induced. Across this transition, we observed that a single electronic spin behaves like a magnetic impurity and leads to the formation of discrete electronic states between the superconducting electrodes. The understanding of such devices is crucial for the development of superconducting nanoelectronics. In the second experiment, we study the Josephson effect in thin films where the electron motion is coupled to its spin. This spin-orbit interaction is essential in a wide number of theoretical works aiming at discover new phases of matter. We demonstrate that spin-orbit coupling can be probed by phase sensitive measurements of the Josephson current., Les jonctions Josephson sont les briques de base des circuits supraconducteurs. Elles sont constituées de deux supraconducteurs séparés par une barrière isolante. Dans cette thèse, nous présentons deux expériences où la barrière isolante est remplacée par un semi-conducteur. Dans la première, nous étudions des nanofils dans le régime du blocage de Coulomb, où le nombre d’électrons peut être controlé, un par un, jusqu’à induire une transition entre un régime métallique et un régime isolant. A travers cette transition, nous avons observé qu’un spin électronique se comporte comme une impureté magnétique et donne lieu à la formation d’états électroniques discrets entre les électrodes supraconductrices. La compréhension de ces dispositifs est essentielle pour le développement de la nanoélectronique à base de supraconducteur.Dans la seconde expérience, nous étudions l’effet Josephson dans des couches minces où le mouvement des électrons dépend de leur orientation de spin. Ce couplage spin-orbite est essentiel dans un grand nombres de travaux théoriques visant à découvrir des nouvelles phases de la matière. Nous démontrons par cette expérience que le couplage spin-orbite peut être sondé par des mesures sensibles à la différence de phase entre les électrodes supraconductrices qui forment la jonction Josephson.

We propose a superconducting thermal memory device that exploits the thermal hysteresis in a flux-controlled, temperature-biased superconducting quantum-interference device (SQUID). This system reveals a flux-controllable temperature bistability, which can be used to define two well-distinguishable thermal logic states. We discuss a suitable writing-reading procedure for these memory states. The time of the memory writing operation is expected to be on the order of ~0.2 ns, for a Nb-based SQUID in thermal contact with a phonon bath at 4:2 K. We suggest a non-invasive readout scheme for the memory states based on the measurement of the effective resonance frequency of a tank circuit inductively coupled to the SQUID. The proposed device paves the way for a practical implementation of thermal logic and computation. The advantage of this proposal is that it represents also an example of harvesting thermal energy in superconducting circuits., 10 pages, 7 figures

Dissertation, RWTH Aachen University, 2018; Aachen, 124 S. (2018). = Dissertation, RWTH Aachen University, 2018, This work presents the setup of a novel 400 mK-14 T-UHV scanning tunneling and atomic force microscopy system using complete UHV-technology also for the cryostat. This allows a more compact system exhibiting a height of only 2.9 m. Key performance indicators of the system are a holding time of 10 days, more than any other published 3He cryostat for SPM, a noise level of ~1pm in vertical displacement measured in open-loop configuration, an energy resolution compatible with an electron temperature of 450 mK, a voltage noise of below 60 μVrms and the ability to map the atomic structure on InSb(110) down to 500 fA. These excellent performance indicators are achieved mainly by introducing a thermal switch between the 1K-pot and the sorption pumped 3He area leading to an effective mechanical decoupling and by careful low-pass filtering all cables entering the cryostat. The whole system including standard UHV preparation and analysis tools has been designed in the thesis of Dr. rer. nat. Stefan Becker in cooperation with Cryovac Tieftemperatur Inc. which provided the cryostat design to fit into the foreseen acoustic shielding room. The room-temperature UHV-components have partly already been assembled. Some modifications to the room temperature system were performed during this work to ameliorate the handling as well as the functionality. The central part of this work is the improvement of the cryostat’s prototype as well as the finalization of the 400 mK-insert. Improvements of the cryostat include modifications on the tanks such as added shields to reduce thermal radiation and filling the liquid nitrogen tank with copper wool to reduce noise by bubbling. A major modification was the change to thermal switches for precooling the 3He, which improved the handling of the insert as well as the thermal coupling significantly. After completion of the system, tests of its scanning probe and magnetotransport abilities have been performed down to low temperatures leading to the performance indicators mentioned above., Published by Aachen

We report an experimental and numerical study of magneto-transport properties of mesoscopic lateral S/N/S superconducting weak links where the N region is made of the same material as the S banks, though with strongly reduced critical temperature. Magnetoresistance oscillations and clear dc and ac Josephson effects are observed. Experimental results are analyzed in the framework of the time-dependent Ginzburg–Landau model for mesoscopic type II superconductors with an inhomogeneous critical temperature. The analysis suggests that dissipative branches of the current–voltage curve of the weak link in the presence of a magnetic field are accounted for by moving 'Josephson-like' vortices. These relatively fast excitations are anisotropic as per the ordinary Josephson vortex in tunnel junctions, but have a normal core like the ordinary Abrikosov vortex in plain superconducting strips. Moreover, unlike the vortex in tunneling junctions, in the lateral S/N/S weak link, the extension of the moving vortex is larger than the extension of the static one. Further, we report in some detail on the lateral proximity effect, and the deviations from the ideality of the current–phase relation of this kind of lateral weak link in the Josephson regime.

In this experimental thesis, we fabricated ferroelectric field-effect devices based on high-Tc superconductors. We grew high-quality epitaxial heterostructures consisting of an ultra-thin (2 to 6 unit cells) film of YBCO and a thin ferroelectric film (BFO-Mn). We fabricated transport measurement microbridges and used a CT-AFM tip to polarise the BFO-Mn outwards or towards the BFO-Mn/YBCO interface. Due to the ferroelectric field-effect, the superconducting properties of the underlying YBCO film were consequently modified. We then used this effect locally in order to design weak links within the microbridges: two regions where the superconducting properties are enhanced are separated by a narrow region where they are depressed. We explored the conditions of existence of a Josephson coupling across this weak link. In parallel, we fabricated ferroelectric junctions. The barrier is an ultra-thin BFO-Mn film sandwiched between a high-Tc superconducting YBCO bottom electrode and a low-Tc superconducting top electrode. Both at room temperature and at low temperature, we characterised the transport properties across the barrier and the resistive switching resulting from the polarisation of the ferroelectric barrier., Les supraconducteurs à haute température critique (HTS) sont des systèmes fortement corrélés. Dans ces matériaux, une petite modification du nombre de porteurs peut avoir de grandes conséquences sur leurs propriétés physiques. C'est le cas lorsqu'un matériau ferroélectrique est à proximité immédiate d'un HTS : de manière locale et rémanente, la polarisation ferroélectrique modifie par effet de champ électrostatique le nombre d'électrons dans le HTS, au voisinage de l'interface avec le ferroélectrique. Cet effet peut être exploité dans le but de définir des structures à géométrie variable : dans un premier cas, des jonctions qui consistent en deux électrodes supraconductrices, séparées par une zone où la supraconductivité a été affaiblie par effet de champ. Dans un second cas, des jonctions tunnel ferroélectriques - à nouveau avec des électrodes supraconductrices - où l'épaisseur de la barrière est modulable par effet de champ ferroélectrique. Les travaux menés au cours de cette thèse visent à développer les matériaux et les technologies de lithographie pour fabriquer de telles structures, et à caractériser les propriétés de transport de ces dernières.

We discuss heat transport in a thermally-biased SQUID in the presence of an external magnetic flux, when a non-negligible inductance of the SQUID ring is taken into account. A properly sweeping driving flux causes the thermal current to modulate and behave hysteretically. The response of this device is analysed as a function of both the hysteresis parameter and degree of asymmetry of the SQUID, highlighting the parameter range over which hysteretic behavior is observable. Markedly, also the temperature of the SQUID shows hysteretic evolution, with sharp transitions characterized by temperature jumps up to, e.g., ~ 38mK for a realistic Al-based setup. In view of these results, the proposed device can effectively find application as a temperature-based superconducting memory element, working even at GHz frequencies by suitably choosing the superconductor on which the device is based., Comment: 9 pages, 10 figures

High critical temperature superconductors (HTS) based devices can have impact in the study of the phase dynamics of Josephson junctions (JJs) thanks to the wide range of junction parameters they offer and to their unconventional properties. Measurements of current-voltage characteristics and of switching current distributions constitute a direct way to classify different regimes of the phase dynamics and of the transport, also in nontrivial case of the moderately damped regime (MDR). MDR is going to be more and more common in JJs with advances in nanopatterning superconductors and synthesizing novel hybrid systems. Distinctive signatures of macroscopic quantum tunneling and of thermal activation in presence of different tunable levels of dissipation have been detected in YBCO grain boundary JJs. Experimental data are supported by Monte Carlo simulations of the phase dynamics, in a wide range of temperatures and dissipation levels. This allows us to quantify dissipation in the MDR and partially reconstruct a phase diagram as guideline for a wide range of moderately damped systems. (C) 2014 Elsevier B.V. All rights reserved.

Combining ferromagnetism and superconductivity can lead to the development of a completely new generation of technology, with unique and powerful characteristics, called superconducting spintronics. The task of developing this, however, is challenging because at the microscopic level the superconducting and ferromagnetic states are intrinsically incompatible. Under certain conditions, however, the conventional (singlet) superconducting state can be converted into the triplet one, with the spins of the electrons forming the Cooper pairs aligned parallel. The triplet state can coexist with ferromagnetism and is very interesting both for applications and from a fundamental point of view. In this thesis we study the electrical properties of small hybrid devices that mainly consist of superconducting and ferromagnetic layers. By measuring the electrical resistance of these devices as a function of parameters such as the temperature or the applied magnetic field, it is possible to indirectly infer important information about the state of the (super)conductivity in the different layers. We investigate different types of devices (multilayers, triplet spin valves and Josephson junctions), in order to address different aspects related to the generation of the triplet state, for a better and better control of the process.

2014 - 2015 In questa Tesi di Dottorato, io e il mio supervisor, il Prof. Roberto De Luca, abbiamo analizzato alcuni particolari dispositivi superconduttori, le giunzioni Josephson e gli SQUIDs (Superconducting Quantum Interference Devices), da un punto di vista semi-classico e quantistico. Con la collaborazione di alcuni professori russi, i Professori Larisa Zherikhina e Andrej Tshovrebov del Lebedev Institute of RAS (Russian Academy of Sciences), a Mosca, Russia and il Prof. George Izmailov del Moscow Aviation Institute (MAI), anche a Mosca. Applicazioni di questi dispositivi (in particolare degli SQUIDs) come rivelatori di Materia Oscura sono state considerate. Noi dapprima descriviamo la nostra attività teorica sulle giunzioni Josephson e gli SQUIDs, e poi sottolineiamo il ruolo degli SQUID come rivelatori di Materia Oscura. Iniziamo con l’analisi microscopica di una catena lineare di N superconduttori, per cui abbiamo considerato interazioni solo tra primi vicini. Nel particolare caso di N = 2 superconduttori accoppiati, così che essi formano una giunzione Josephson, abbiamo ottenuto le stesse relazioni caratterizzanti il modello di Feynman, che descrive, da un punto di vista quantistico, questo sistema. I risultati confermano la validità del modello semiclassico di Ohta, che rappresenta l’estensione del modello di Feynman a una giunzione Josephson connessa a una sorgente di f.e.m. Abbiamo poi analizzato le proprietà teoriche delle giunzioni Josephson a doppia barriera e a tripla barriera (DBJJ e TBJJ rispettivamente). Per la DBJJ, che è un sistema superconduttivo a tre elettrodi, in cui l’elettrodo intermedio è considerato come un puro sistema quantistico, abbiamo ipotizzato accoppiamenti non omogenei tra gli elettrodi superconduttivi 1-2 e 2-3. La costante di accoppiamento tra gli elettrodi 1-3 si prende piccola in confronto alle precedenti. Per la TBJJ, un sistema superconduttivo a quattro elettrodi, in cui gli elettrodi più interni sono trattati come un puro sistema quantistico, le costanti di accoppiamento tra i layers 1-2, 2-3 e 3-4 sono diverse, così anche in questo caso non abbiamo accoppiamenti omogenei, e le costanti di accoppiamento tra 1-3 e 2-4 sono considerate minori di quelle precedenti. Per scopo di semplicità, prendiamo la differenza di fase superconduttiva degli elettrodi più interni 2 e 3 uguali a zero. Sotto queste ipotesi, usando il modello semi-classico di Ohta, abbiamo ottenuto la relazione corrente-fase (CPR) per questi sistemi. Si nota che questa relazione è diversa da quella sinusoidale, che caratterizza la semplice giunzione Josephson (SJJ), ed è in buon accordo sia con i risultati teorici ottenuti da Brinkmann, basati su un approccio microscopico, e anche con i risultati sperimentali trovati da Nevirkovets et al. Gli ultimi risultati sono basati sull’osservazione dei passi di Shapiro, e l’analisi delle loro ampiezze in funzione della d.d.p. applicata... [a cura dell'autore] XIV n.s.

We consider a model for a single molecule with a large frozen spin sandwiched in between two BCS superconductors at equilibrium, and show that this system has a $\pi$ junction behavior at low temperature. The $\pi$ shift can be reversed by varying the other parameters of the system, e.g., temperature or the position of the quantum dot level, implying a controllable $\pi$ junction with novel application as a Josephson current switch. We show that the mechanism leading to the $\pi$ shift can be explained simply in terms of the contributions of the Andreev bound states and of the continuum of states above the superconducting gap. The free energy for certain configuration of parameters shows a bistable nature, which is a necessary pre-condition for achievement of a qubit.

Made available in DSpace on 2018-08-01T22:30:02Z (GMT). No. of bitstreams: 1 tese_8945_Tese Final Marcio de Sousa Bolzan.pdf: 9785147 bytes, checksum: 365b1d8e3f862206cc9c3c65adf93c4d (MD5) Previous issue date: 2015-05-15 O espalhamento da corrente supercondutora na passagem entre grãos numa cerâmica policristalina tem sido estudado por vários pesquisadores, em especial nestes últimos 20 anos. Neste trabalho utilizamos o conhecimento da estrutura entre os grãos encontrada nas cerâmicas supercondutoras a base de mercúrio, cuidadosamente produzidas na UFES, associado a uma modelagem de interferência quântica macroscópica para descrever o comportamento da corrente crítica, quando a amostra é submetida à presença de campos magnéticos. Associando a energia de aprisionamento dos vórtices (pinning) a uma modelagem mais detalhada do contorno de grão conseguimos descrever teoricamente o comportamento observado da corrente crítica. O modelo proposto adiciona uma nova visão sobre a correlação entre a corrente crítica e a descrição do contorno de grão, evidenciando o papel de parâmetros importantes oriundos da distribuição de tamanhos de junções entre grãos e do potencial de aprisionamento de vórtices na descrição correta dos valores medidos da corrente crítica em função do campo aplicado. Portanto, concluímos neste trabalho a proposta de um modelo de junção S1S2𝐼𝑆2S1 associado a um modelagem estatística que descreve com boa qualidade de previsão o comportamento da corrente crítica em amostras cerâmicas policristalinas a base de mercúrio, quando a amostra é submetida a um campo magnético externo.

We study the relation between Josephson dynamics and topological excitations in a dilute Bose-Einstein condensate confined in a double-well trap. We show that the phase slips responsible for the self-trapping regime are created by vortex rings entering and annihilating inside the weak-link region or created at the center of the barrier and expanding outside the system. Large amplitude oscillations just before the onset of self-trapping are also strictly connected with the dynamics of vortex rings at the edges of the inter-well barrier. Our results extend and analyze the dynamics of the vortex-induced phase slippages suggested a few decades ago in relation to the "ac" Josephson effect of superconducting and superfluid helium systems., 6 pages, 5 figures

A 10 V programmable Josephson voltage standard system has been installed at the National Research Council Canada. The current margins for the first Josephson step at either current polarity are greater than 1 mA. A preliminary direct comparison of this programmable system with a hysteretic Josephson voltage standard is performed at 10 V., 29th Conference on Precision Electromagnetic Measurements, CPEM 2014, August 24-29, 2014, Series: CPEM Digest

Ce mémoire présente ma contribution à l'avènement des circuits supraconducteurs comme composant de base des systèmes d'information quantique. Les variables macroscopiques des circuits électriques, telles que la tension et le courant, obéissent aux lois de la mécanique quantique tant qu'elles sont suffisamment découplées de leur environnement. Depuis que les premiers qubits supraconducteurs ont été réalisés il y a 15 ans, leurs temps de cohérence ont augmenté de 5 ordres de grandeur grâce à un meilleur contrôle de l'environnement électromagnétique des jonctions Josephson. Sur ces systèmes remarquables, nous avons réalisé des expériences qui illustrent quelques uns des aspects les plus non classiques de l'information quantique. - Les variables quantiques fluctuent même à température nulle. Ces fluctuations de point zéro imposent à un détecteur d'ajouter au moins un minimum de bruit. Nous explorons les limites quantiques de l'amplification pour des signaux microonde itinérants, et décrivons un circuit supraconducteur concret, le mixeur Josephson, capable d'atteindre cette limite. - Contrairement à l'information classique, l'information quantique peut être stockée de manière délocalisée dans l'espace grâce à l'intrication. Nous décrivons le premier circuit capable d'intriquer deux modes de champ microonde itinérants à différentes fréquences et sur des lignes de transmission séparées. Nous présentons aussi un dispositif capable de stocker un champ microonde intriqué avec un champ propageant. - La mesure d'un système quantique conduit à une réaction sur son état sans équivalent classique. Nous présentons une expérience où la trajectoire de l'état qubit est protégée de la décohérence par rétroaction basée sur la mesure. Cette expérience illustre le rôle central de la réaction d'une mesure quantique pour le contrôle par rétroaction et donc pour la correction quantique d'erreur. - Les mesures faibles fournissent une information partielle sur un système. Comme les mesures quantiques modifient l'état du système, les règles classiques de Bayes doivent être modifiées pour prédire la probabilité de trouver un résultat donné sachant qu'un certain résultat sera trouvé dans une autre mesure future. Nous décrivons une expérience où la fluorescence émise par un qubit est enregistrée dans le temps, ce qui peut être interprété comme une mesure faible et continue du qubit. L'influence de conditions sur les mesures passées et futures est explorée.