Incoherent Noise and Quantum Information Processing

Incoherence in the controlled Hamiltonian is an important limitation on the precision of coherent control in quantum information processing. Incoherence can typically be modelled as a distribution of unitary processes arising from slowly varying experimental parameters. We show how it introduces artifacts in quantum process tomography and we explain how the resulting estimate of the superoperator may not be completely positive. We then go on to attack the inverse problem of extracting an effective distribution of unitaries that characterizes the incoherence via a perturbation theory analysis of the superoperator eigenvalue spectra.Comment: 15 pages, 5 figures, replaced with future JCP published versio

Transient shivering during Wada test provides insight into human thermoregulation

Some patients with pharmacoresistant epilepsy undergoing the Wada test experience transient shivering. The purpose of this study was to investigate various clinical and radiographic characteristics of these individuals to delineate underlying mechanisms of this phenomenon.A systematic review of prospectively collected information on patients undergoing the Wada test was performed. All demographic, clinical, and radiographic information was obtained and reviewed by the appropriate expert in the field; statistical analysis was performed to determine the predictors of transient shivering.A total of 120 consecutive carotid artery injections in 59 patients were included in the study. Shivering was observed in 46% of the patients, and it was not significantly affected by gender, age, location of epileptogenic zone, brain lesion on magnetic resonance imaging (MRI), side of the first injection, duration of the hemiparesis, or excess slow wave activity on electroencephalography (EEG). However, shivering was more likely to follow sodium amobarbital injection if there was no filling of the posterior circulation on cerebral angiogram.Transient shivering during the Wada test is common. A transient but selective functional lesion of the anterior hypothalamus produced by the effects of sodium amobarbital may result in disinhibition of the posterior hypothalamus and other brainstem thermoregulatory centers, thereby inducing transient shivering.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78595/1/j.1528-1167.2009.02398.x.pd

Experimental Implementation of a Concatenated Quantum Error-Correcting Code

Concatenated coding provides a general strategy to achieve the desired level of noise protection in quantum information storage and transmission. We report the implementation of a concatenated quantum error-correcting code able to correct against phase errors with a strong correlated component. The experiment was performed using liquid-state nuclear magnetic resonance techniques on a four spin subsystem of labeled crotonic acid. Our results show that concatenation between active and passive quantum error-correcting codes offers a practical tool to handle realistic noise contributed by both independent and correlated errors.Comment: 4 pages, 2 encapsulated eps figures. REVTeX4 styl

Characterization of a two-transmon processor with individual single-shot qubit readout

We report the characterization of a two-qubit processor implemented with two capacitively coupled tunable superconducting qubits of the transmon type, each qubit having its own non-destructive single-shot readout. The fixed capacitive coupling yields the \sqrt{iSWAP} two-qubit gate for a suitable interaction time. We reconstruct by state tomography the coherent dynamics of the two-bit register as a function of the interaction time, observe a violation of the Bell inequality by 22 standard deviations after correcting readout errors, and measure by quantum process tomography a gate fidelity of 90%

Franck Beaupérin (dir.), L’armistice du 11 novembre 1918. Objets, documents et souvenirs du patrimoine militaire

Dans la masse de toutes les publications éditées à l’occasion du 90e anniversaire de l’Armistice, on aura plaisir à mentionner cet agréable ouvrage destiné à mettre en valeur les objets et les documents iconographiques conservés, au sein du ministère de la Défense, par les musées (Armée, Marine, Air et Espace, Service de santé des armées), l’Établissement de communication et de production audiovisuelle et le Service historique. Publié sous la direction du lieutenant Franck Beaupérin, préfacé ..

Arlette Jouanna, La Saint-Barthélemy. Les mystères d’un crime d’État (24 août 1572)

Traumatisme majeur de l’histoire de France, le massacre de la Saint-Barthélemy a suscité chez les historiens nombre de controverses et d’interprétations, notamment celle d’une volonté de Charles IX d’éradiquer la religion réformée. Dans le prolongement des travaux conduits par Jean-Louis Bourgeon, Denis Crouzet et Janine Garrisson, Arlette Jouanna propose une nouvelle lecture de l’événement, notamment à la lumière des archives de Simancas. Elle démontre la volonté du roi « d’affirmer la toute..

Rémi Monaque, Suffren. Un destin inachevé

En choisissant de consacrer une étude à Pierre-André de Suffren, l’amiral Monaque a relevé le pari de proposer une nouvelle biographie de celui qui demeure l’une des plus grandes personnalités de l’histoire de la marine européenne. Le défi était d’autant plus difficile que le personnage possède une personnalité fort complexe qui n’a cessé de susciter des controverses, essentiellement pour ce qui concerne ses méthodes de commandement. Fort de sa propre expérience – ayant lui-même servi dans la..