Dilated Spatial Generative Adversarial Networks for Ergodic Image Generation

Generative models have recently received renewed attention as a result of adversarial learning. Generative adversarial networks consist of samples generation model and a discrimination model able to distinguish between genuine and synthetic samples. In combination with convolutional (for the discriminator) and de-convolutional (for the generator) layers, they are particularly suitable for image generation, especially of natural scenes. However, the presence of fully connected layers adds global dependencies in the generated images. This may lead to high and global variations in the generated sample for small local variations in the input noise. In this work we propose to use architec-tures based on fully convolutional networks (including among others dilated layers), architectures specifically designed to generate globally ergodic images, that is images without global dependencies. Conducted experiments reveal that these architectures are well suited for generating natural textures such as geologic structures

Circuit QED with a Nonlinear Resonator : ac-Stark Shift and Dephasing

We have performed spectroscopic measurements of a superconducting qubit dispersively coupled to a nonlinear resonator driven by a pump microwave field. Measurements of the qubit frequency shift provide a sensitive probe of the intracavity field, yielding a precise characterization of the resonator nonlinearity. The qubit linewidth has a complex dependence on the pump frequency and amplitude, which is correlated with the gain of the nonlinear resonator operated as a small-signal amplifier. The corresponding dephasing rate is found to be close to the quantum limit in the low-gain limit of the amplifier.Comment: Paper : 4 pages, 3 figures; Supplementary material : 1 page, 1 figur

Addressing the clumsiness loophole in a Leggett-Garg test of macrorealism

The rise of quantum information theory has lent new relevance to experimental tests for non-classicality, particularly in controversial cases such as adiabatic quantum computing superconducting circuits. The Leggett-Garg inequality is a "Bell inequality in time" designed to indicate whether a single quantum system behaves in a macrorealistic fashion. Unfortunately, a violation of the inequality can only show that the system is either (i) non-macrorealistic or (ii) macrorealistic but subjected to a measurement technique that happens to disturb the system. The "clumsiness" loophole (ii) provides reliable refuge for the stubborn macrorealist, who can invoke it to brand recent experimental and theoretical work on the Leggett-Garg test inconclusive. Here, we present a revised Leggett-Garg protocol that permits one to conclude that a system is either (i) non-macrorealistic or (ii) macrorealistic but with the property that two seemingly non-invasive measurements can somehow collude and strongly disturb the system. By providing an explicit check of the invasiveness of the measurements, the protocol replaces the clumsiness loophole with a significantly smaller "collusion" loophole.Comment: 7 pages, 3 figure

Tunable resonators for quantum circuits

We have designed, fabricated and measured high-Q $\lambda/2$ coplanar waveguide microwave resonators whose resonance frequency is made tunable with magnetic field by inserting a DC-SQUID array (including 1 or 7 SQUIDs) inside. Their tunability range is 30% of the zero field frequency. Their quality factor reaches up to 3$\times10^4$. We present a model based on thermal fluctuations that accounts for the dependance of the quality factor with magnetic field.Comment: subm. to JLTP (Proc. of LTD12 conference

Molecular epidemiology of foot and mouth disease virus (FMDV) in Chad

Foot and mouth disease (FMD) is a highly contagious viral disease affecting domestic and wild artiodactyl animals. Its causative agent is foot-and–mouth disease virus (FMDV: Aphtovirus, Picornaviridae). Seven immunologically distinct serotypes (O, A, C, Asia1, SAT 1, SAT 2 and SAT 3) and many subtypes are described worldwide. FMD is one of the most economically devastating diseases of livestock. It is enzootic in many parts of the world including sub-Saharan Africa. Most studies on FMD are carried out in countries where control measures are implemented. On the other hand, in regions such as sub-Saharan Africa, where FMD is endemic and new strains are likely to spread due to animal movements, there are very few published studies on FMDV molecular epidemiology. In Chad particularly, no studies have been conducted to investigate circulating FMDV strains. This work aims to understand the transmission process of FMDV in the pastoral area of Chad, based on a stratified sample of livestock herds (fig. 1). Susceptible animals (cattle, sheep, goats, and camels) were sampled according to the a priori risk of FMD spread in Chad, evaluated by a qualitative risk analysis combining the risks of its introduction and dissemination. In total, 2,195 sera and eight epithelium samples were collected from October to December 2016 in six districts (Batha-Ouest, Batha-Est, Ennedi-Ouest, Wadi-fira, Chari and Lac Wey). Five out of the eight samples tested positive by real-time RT-PCR targeting the FMDV IRES region or the FMDV 3D polymerase coding region. Further analyses targeting specifically the VP1 coding region showed SAT2 type for four samples out of these five FMDV positive samples. Finally amplification and sequencing of the VP1 coding region of these four SAT2 positive samples was carried out to characterize more precisely the strains. Preliminary results were obtained for one sample, confirming the presence of a SAT2 virus, closely related to FMDV SAT2 viruses isolated in Egypt in 2012. Serological analyses are pending. Filling the gap of knowledge concerning the FMDV strains circulating in Chad could both contribute to a better selection of vaccine strains but also to an update of the available molecular epidemiology data of FMD virus in sub-Saharan Africa in general. (Résumé d'auteur

Single-shot qubit readout in circuit Quantum Electrodynamics

The future development of quantum information using superconducting circuits requires Josephson qubits [1] with long coherence times combined to a high-fidelity readout. Major progress in the control of coherence has recently been achieved using circuit quantum electrodynamics (cQED) architectures [2, 3], where the qubit is embedded in a coplanar waveguide resonator (CPWR) which both provides a well controlled electromagnetic environment and serves as qubit readout. In particular a new qubit design, the transmon, yields reproducibly long coherence times [4, 5]. However, a high-fidelity single-shot readout of the transmon, highly desirable for running simple quantum algorithms or measur- ing quantum correlations in multi-qubit experiments, is still lacking. In this work, we demonstrate a new transmon circuit where the CPWR is turned into a sample-and-hold detector, namely a Josephson Bifurcation Amplifer (JBA) [6, 7], which allows both fast measurement and single-shot discrimination of the qubit states. We report Rabi oscillations with a high visibility of 94% together with dephasing and relaxation times longer than 0:5 \mu\s. By performing two subsequent measurements, we also demonstrate that this new readout does not induce extra qubit relaxation.Comment: 14 pages including 4 figures, preprint forma

Demonstration of quantum Zeno effect in a superconducting phase qubit

Quantum Zeno effect is a significant tool in quantum manipulating and computing. We propose its observation in superconducting phase qubit with two experimentally feasible measurement schemes. The conventional measurement method is used to achieve the proposed pulse and continuous readout of the qubit state, which are analyzed by projection assumption and Monte Carlo wave-function simulation, respectively. Our scheme gives a direct implementation of quantum Zeno effect in a superconducting phase qubit.Comment: 5 pages, 4 figure

Quantum information processing using quasiclassical electromagnetic interactions between qubits and electrical resonators

Electrical resonators are widely used in quantum information processing, by engineering an electromagnetic interaction with qubits based on real or virtual exchange of microwave photons. This interaction relies on strong coupling between the qubits' transition dipole moments and the vacuum fluctuations of the resonator in the same manner as cavity quantum electrodynamics (QED), and has consequently come to be called 'circuit QED' (cQED). Great strides in the control of quantum information have already been made experimentally using this idea. However, the central role played by photon exchange induced by quantum fluctuations in cQED does result in some characteristic limitations. In this paper, we discuss an alternative method for coupling qubits electromagnetically via a resonator, in which no photons are exchanged, and where the resonator need not have strong quantum fluctuations. Instead, the interaction can be viewed in terms of classical, effective 'forces' exerted by the qubits on the resonator, and the resulting resonator dynamics used to produce qubit entanglement are purely classical in nature. We show how this type of interaction is similar to that encountered in the manipulation of atomic ion qubits, and we exploit this analogy to construct two-qubit entangling operations that are largely insensitive to thermal or other noise in the resonator, and to its quality factor. These operations are also extensible to larger numbers of qubits, allowing interactions to be selectively generated among any desired subset of those coupled to a single resonator. Our proposal is potentially applicable to a variety of physical qubit modalities, including superconducting and semiconducting solid-state qubits, trapped molecular ions, and possibly even electron spins in solids.United States. Dept. of Defense. Assistant Secretary of Defense for Research & Engineering (United States. Air Force Contract FA8721-05-C-0002

Dancing Greek Antiquity in Private and Public: Isadora Duncan's Early Patronage in Paris

This paper maps Isadora Duncan’s navigation of public and private venues, audiences, and receptions of “Greek” dances from her early career in Paris. I explore Duncan's relationship with Paris’ lesbian communities and the proliferation of ancient Greek dance in both private and public venues. Through comparisons to her contemporaries I contend that Duncan was aware of her early audiences’ interest in exotic and erotic representations of antiquity, and that she realigned these aspects of her art in later writings to appeal to changing aesthetics and interpretations of antiquity