Solid-state electron spin lifetime limited by phononic vacuum modes.

Longitudinal relaxation is the process by which an excited spin ensemble decays into its thermal equilibrium with the environment. In solid-state spin systems, relaxation into the phonon bath usually dominates over the coupling to the electromagnetic vacuum1-9. In the quantum limit, the spin lifetime is determined by phononic vacuum fluctuations 10 . However, this limit was not observed in previous studies due to thermal phonon contributions11-13 or phonon-bottleneck processes10, 14,15. Here we use a dispersive detection scheme16,17 based on cavity quantum electrodynamics18-21 to observe this quantum limit of spin relaxation of the negatively charged nitrogen vacancy (NV-) centre 22 in diamond. Diamond possesses high thermal conductivity even at low temperatures 23 , which eliminates phonon-bottleneck processes. We observe exceptionally long longitudinal relaxation times T1 of up to 8 h. To understand the fundamental mechanism of spin-phonon coupling in this system we develop a theoretical model and calculate the relaxation time ab initio. The calculations confirm that the low phononic density of states at the NV- transition frequency enables the spin polarization to survive over macroscopic timescales.

Coherent Coupling of Remote Spin Ensembles via a Cavity Bus.

We report coherent coupling between two macroscopically separated nitrogen-vacancy electron spin ensembles in a cavity quantum electrodynamics system. The coherent interaction between the distant ensembles is directly detected in the cavity transmission spectrum by observing bright and dark collective multiensemble states and an increase of the coupling strength to the cavity mode. Additionally, in the dispersive limit we show transverse ensemble-ensemble coupling via virtual photons.

Outcomes of endoscopic ethmoidectomy performed on a day-case basis: a prospective bi-centric study.

Evaluation of endoscopic ethmoidectomy performed as a day-case in terms of security, quality, and satisfaction of the patient. This prospective observatory bi-centric study over 1 year included 74 patients undergoing an ethmoidectomy respecting the eligibility criteria of ambulatory care. We recorded patients' demographic data, operative details, satisfaction, postoperative course, and follow-up results. Nasal symptoms were evaluated by SNOT-22 on preoperative appointment and postoperatively at D30. No non-absorbable nasal packing was used, eventually in the case of preoperative-bleeding absorbable gelatine packing. The postoperative follow-up took place at D1 by phone call and at D10 and D30 to assess complications, Visual Analogue Scale, and state of ethmoidal corridors by endoscopic exam. Patients benefited of bilateral ethmoidectomy in 82.4 % cases associated with septoplasty in 42 %. The majority (95 %) was discharged on the same day. Only one patient had bleeding at D0 and was kept in standard hospitalization, such as three other patients for medical or organizational reasons not related to surgery. At D1, 23 % described postoperative light bleeding but needed no revisit and pain was estimated at 1.3 (VAS). No readmission was observed, and no major complication was noted. SNOT-22 decreased successfully by 56 %, statistically related to postoperative treatment of corticosteroids and in the case of Samter triad. 97 % of patients were satisfied of the ambulatory care. These results suggest that within an experienced and dedicated day-case medical and paramedical team, ethmoidectomy can be safely performed on a day-case basis with high quality of taking care and satisfaction of patients.

Demonstration of two-qubit algorithms with a superconducting quantum processor.

Quantum computers, which harness the superposition and entanglement of physical states, could outperform their classical counterparts in solving problems with technological impact-such as factoring large numbers and searching databases. A quantum processor executes algorithms by applying a programmable sequence of gates to an initialized register of qubits, which coherently evolves into a final state containing the result of the computation. Building a quantum processor is challenging because of the need to meet simultaneously requirements that are in conflict: state preparation, long coherence times, universal gate operations and qubit readout. Processors based on a few qubits have been demonstrated using nuclear magnetic resonance, cold ion trap and optical systems, but a solid-state realization has remained an outstanding challenge. Here we demonstrate a two-qubit superconducting processor and the implementation of the Grover search and Deutsch-Jozsa quantum algorithms. We use a two-qubit interaction, tunable in strength by two orders of magnitude on nanosecond timescales, which is mediated by a cavity bus in a circuit quantum electrodynamics architecture. This interaction allows the generation of highly entangled states with concurrence up to 94 per cent. Although this processor constitutes an important step in quantum computing with integrated circuits, continuing efforts to increase qubit coherence times, gate performance and register size will be required to fulfil the promise of a scalable technology.

Implementation of the Dicke lattice model in hybrid quantum system arrays.

Generalized Dicke models can be implemented in hybrid quantum systems built from ensembles of nitrogen-vacancy (NV) centers in diamond coupled to superconducting microwave cavities. By engineering cavity assisted Raman transitions between two spin states of the NV defect, a fully tunable model for collective light-matter interactions in the ultrastrong coupling limit can be obtained. Our analysis of the resulting nonequilibrium phases for a single cavity and for coupled cavity arrays shows that different superradiant phase transitions can be observed using existing experimental technologies, even in the presence of large inhomogeneous broadening of the spin ensemble. The phase diagram of the Dicke lattice model displays distinct features induced by dissipation, which can serve as a genuine experimental signature for phase transitions in driven open quantum systems.

[Retrospective evaluation of short tympanostomy tubes efficacy in case of recurrent acute otitis media on an infant population]. / Evaluation rétrospective de l'efficacité des aérateurs trans-tympaniques courts en cas d'otites moyennes aiguës récidivantes chez le nourrisson.

INTRODUCTION: The aim of this study is to appreciate the results of short-tympanostomy tubes (ST) in case of recurrent acute otitis media (AOM), and to appreciate the risk factors of recurrent AOM. METHODS: This retrospective chart study concerns infants who had STT placement surgery forrecurrent AOM, between 2007 and 2011. Demographic data, anamnesis, efficacy and postoperative follow-up were analyzed. RESULTS: Forty-nine children were included in the study (30 boys, 19 girls; 7 months to 2 years-old, median age 1.4 year). Two-thirds attended a day-care center, one third was an onlychild. One quarter had an anemia. Anti-Haemophilus and anti-pneumococcus vaccinations were up-to-date in 87.5%. After STT placement, 20 children (40.8%) did not present any new episode of AOM. This result did not vary with adenoidectomy. Among the ones that relapsed AOM after STT, 48.3% presented with only one episode. For two thirds of the patients, no general antibiotic treatment was necessary as long as the STT were in place. Half STT have been spontaneously expulsed between 6 and 12 months. Thirteen infants (37.1%) had new episodes of AOM after STT expulsion and 5 (38.5%) needed new tube placement. CONCLUSION: This study confirms that day care and siblings are risk factors of recurrent AOM, but does not confirm potential role of the anemia. STT placement decreased effectively AOM recurrences, their severity and the need for antibiotics prescriptions. No residual perforation was encountered in this study.

Resolving photon number states in a superconducting circuit.

Electromagnetic signals are always composed of photons, although in the circuit domain those signals are carried as voltages and currents on wires, and the discreteness of the photon's energy is usually not evident. However, by coupling a superconducting quantum bit (qubit) to signals on a microwave transmission line, it is possible to construct an integrated circuit in which the presence or absence of even a single photon can have a dramatic effect. Such a system can be described by circuit quantum electrodynamics (QED)-the circuit equivalent of cavity QED, where photons interact with atoms or quantum dots. Previously, circuit QED devices were shown to reach the resonant strong coupling regime, where a single qubit could absorb and re-emit a single photon many times. Here we report a circuit QED experiment in the strong dispersive limit, a new regime where a single photon has a large effect on the qubit without ever being absorbed. The hallmark of this strong dispersive regime is that the qubit transition energy can be resolved into a separate spectral line for each photon number state of the microwave field. The strength of each line is a measure of the probability of finding the corresponding photon number in the cavity. This effect is used to distinguish between coherent and thermal fields, and could be used to create a photon statistics analyser. As no photons are absorbed by this process, it should be possible to generate non-classical states of light by measurement and perform qubit-photon conditional logic, the basis of a logic bus for a quantum computer.

Generating single microwave photons in a circuit.

Microwaves have widespread use in classical communication technologies, from long-distance broadcasts to short-distance signals within a computer chip. Like all forms of light, microwaves, even those guided by the wires of an integrated circuit, consist of discrete photons. To enable quantum communication between distant parts of a quantum computer, the signals must also be quantum, consisting of single photons, for example. However, conventional sources can generate only classical light, not single photons. One way to realize a single-photon source is to collect the fluorescence of a single atom. Early experiments measured the quantum nature of continuous radiation, and further advances allowed triggered sources of photons on demand. To allow efficient photon collection, emitters are typically placed inside optical or microwave cavities, but these sources are difficult to employ for quantum communication on wires within an integrated circuit. Here we demonstrate an on-chip, on-demand single-photon source, where the microwave photons are injected into a wire with high efficiency and spectral purity. This is accomplished in a circuit quantum electrodynamics architecture, with a microwave transmission line cavity that enhances the spontaneous emission of a single superconducting qubit. When the qubit spontaneously emits, the generated photon acts as a flying qubit, transmitting the quantum information across a chip. We perform tomography of both the qubit and the emitted photons, clearly showing that both the quantum phase and amplitude are transferred during the emission. Both the average power and voltage of the photon source are characterized to verify performance of the system. This single-photon source is an important addition to a rapidly growing toolbox for quantum optics on a chip.

Coupling superconducting qubits via a cavity bus.

Superconducting circuits are promising candidates for constructing quantum bits (qubits) in a quantum computer; single-qubit operations are now routine, and several examples of two-qubit interactions and gates have been demonstrated. These experiments show that two nearby qubits can be readily coupled with local interactions. Performing gate operations between an arbitrary pair of distant qubits is highly desirable for any quantum computer architecture, but has not yet been demonstrated. An efficient way to achieve this goal is to couple the qubits to a 'quantum bus', which distributes quantum information among the qubits. Here we show the implementation of such a quantum bus, using microwave photons confined in a transmission line cavity, to couple two superconducting qubits on opposite sides of a chip. The interaction is mediated by the exchange of virtual rather than real photons, avoiding cavity-induced loss. Using fast control of the qubits to switch the coupling effectively on and off, we demonstrate coherent transfer of quantum states between the qubits. The cavity is also used to perform multiplexed control and measurement of the qubit states. This approach can be expanded to more than two qubits, and is an attractive architecture for quantum information processing on a chip.

A horizontally polarizing liquid trap enhances the tabanid-capturing efficiency of the classic canopy trap.

Host-seeking female tabanid flies, that need mammalian blood for the development of their eggs, can be captured by the classic canopy trap with an elevated shiny black sphere as a luring visual target. The design of more efficient tabanid traps is important for stock-breeders to control tabanids, since these blood-sucking insects can cause severe problems for livestock, especially for horse- and cattle-keepers: reduced meat/milk production in cattle farms, horses cannot be ridden, decreased quality of hides due to biting scars. We show here that male and female tabanids can be caught by a novel, weather-proof liquid-filled black tray laid on the ground, because the strongly and horizontally polarized light reflected from the black liquid surface attracts water-seeking polarotactic tabanids. We performed field experiments to reveal the ideal elevation of the liquid trap and to compare the tabanid-capturing efficiency of three different traps: (1) the classic canopy trap, (2) the new polarization liquid trap, and (3) the combination of the two traps. In field tests, we showed that the combined trap captures 2.4-8.2 times more tabanids than the canopy trap alone. The reason for the larger efficiency of the combined trap is that it captures simultaneously the host-seeking female and the water-seeking male and female tabanids. We suggest supplementing the traditional canopy trap with the new liquid trap in order to enhance the tabanid-capturing efficiency.

Cavity QED with magnetically coupled collective spin states.

We report strong coupling between an ensemble of nitrogen-vacancy center electron spins in diamond and a superconducting microwave coplanar waveguide resonator. The characteristic scaling of the collective coupling strength with the square root of the number of emitters is observed directly. Additionally, we measure hyperfine coupling to (13)C nuclear spins, which is a first step towards a nuclear ensemble quantum memory. Using the dispersive shift of the cavity resonance frequency, we measure the relaxation time of the NV center at millikelvin temperatures in a nondestructive way.

Responses to immunization in the thymus of the adult mouse.

The rate of synthesis of RNA in the thymus glands of adult mice increased after immunization with sheep red blood cells (SRBC). The specific activity of some fractions of RNA, separated first by density gradient centrifugation and then by polyacrylamide gel electrophoresis, was 16-fold higher on day 3 after immunization than control mice not injected. RNA synthesis in the thymus was inhibited by rabbit anti-mouse thymus serum, injected along with antigen. A material was found in RNA extracts from the thymus glands of mice immunized with SRBC which converted a small proportion of either spleen cells or peritoneal cells from nonimmunized mice to form sheep cell hemolysins. Neither extracts from the glands of nonimmunized mice nor the livers of immunized mice were active. Extracts from the thymus glands of mice immunized with rabbit red blood cells (RRBC) were inactive and activity was destroyed by ribonudease. The residual antigen content was not determined. Biologically active extracts from the thymus had a different electrophoretic mobility from active extracts from the spleen.

Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics.

The interaction of matter and light is one of the fundamental processes occurring in nature, and its most elementary form is realized when a single atom interacts with a single photon. Reaching this regime has been a major focus of research in atomic physics and quantum optics for several decades and has generated the field of cavity quantum electrodynamics. Here we perform an experiment in which a superconducting two-level system, playing the role of an artificial atom, is coupled to an on-chip cavity consisting of a superconducting transmission line resonator. We show that the strong coupling regime can be attained in a solid-state system, and we experimentally observe the coherent interaction of a superconducting two-level system with a single microwave photon. The concept of circuit quantum electrodynamics opens many new possibilities for studying the strong interaction of light and matter. This system can also be exploited for quantum information processing and quantum communication and may lead to new approaches for single photon generation and detection.

A scalable architecture for quantum computation with molecular nanomagnets.

A proposal for a magnetic quantum processor that consists of individual molecular spins coupled to superconducting coplanar resonators and transmission lines is carefully examined. We derive a simple magnetic quantum electrodynamics Hamiltonian to describe the underlying physics. It is shown that these hybrid devices can perform arbitrary operations on each spin qubit and induce tunable interactions between any pair of them. The combination of these two operations ensures that the processor can perform universal quantum computations. The feasibility of this proposal is critically discussed using the results of realistic calculations, based on parameters of existing devices and molecular qubits. These results show that the proposal is feasible, provided that molecules with sufficiently long coherence times can be developed and accurately integrated into specific areas of the device. This architecture has an enormous potential for scaling up quantum computation thanks to the microscopic nature of the individual constituents, the molecules, and the possibility of using their internal spin degrees of freedom.

1-(3'-O-acyl)-beta-glucosyl-N-dihydroxypentatriacontadienoylsphingosine, a major component of the glucosylceramides of pig and human epidermis.

The least polar of four chromatographically distinct glucosylceramides in both pig and human epidermis, was identified from its infrared spectrum and degradation products as O-acylglucosylceramide. Permethylation studies indicated that the acyl group was attached predominantly (80%) to the C-3 of glucose in the pig and only to the C-3 glucose in the human O-acylglucosylceramide. Octadecadienoic acid was the major acid esterified to glucose in both pig and human O-acylglucosylceramides and sphingenine, sphinganine and heptadecasphinganine accounted for most of the long chain bases (87% in pig, 80% in human). Chromatographic and chemical-evidence suggested that a single, unknown unsaturated dihydroxy fatty acid with more than 30 carbon atoms was attached through the amide link to the sphingosines. This was confirmed by mass spectrometry. Precise mass measurements indicated that the acid had a relative molecular mass of 550.496115 (C35H66O4) and was a dihydroxy acid with two double bonds. Other mass spectrometric data suggested that the hydroxyl groups and double bonds were confined to the region between C-16 and C-20. The evidence indicated that the O-acylglucosylceramide in pig epidermis and, by the close similarity of its properties, probably that in human epidermis also was 1-(3'-O-acyl)-beta-glucosyl-N-dihydroxypentatriacontadienoylsphingosine.

Comparison between tsetse fly synthetic diet and bovine blood on reproduction and survivorship in Tabanus nigrovittatus (Diptera: Tabanidae).

A synthetic diet, developed for tsetse flies and fed to Tabanus nigrovittatus Macquart before the 2nd gonotrophic cycle, supported complete egg maturation. T. nigrovittatus is autogenous only during the 1st cycle. Overall, 52% of females fed bovine blood and 46% fed the synthetic diet produced mature, stage 10 follicles. Of these, 76% of the blood-fed females and 65% of those fed the synthetic diet laid egg masses, all of which hatched. The median adult survivorship was 9 d for blood-fed and 8 d for those fed the synthetic diet.

Mass spectrometry of volatile mercury salts.

The integrated ion current method is applied to the determination of mug quantities of mercury(II) chloride. The mass spectra of both mercury(I) and (II) chlorides indicate that the analytical reagent grade chemicals contain traces of mercury(II) bromide and iodide.

Mass spectrometric analysis of carbon monoxide-nitrogen mixtures.

A method for the analysis of gas mixtures containing both carbon monoxide and nitrogen, by using a single-focussing mass spectrometer, is described. It involves measurement of the mass spectrum of a gas sample before and after conversion of the carbon monoxide present into carbon dioxide by means of the Schütze catalyst.

Analytical mass spectrometry.

A review is made of the basic theory, instrumentation and application of mass spectrometry, with special reference to the development of the equipment and its impact on the scope of application.

Absorption spectrophotometry.

A review is given of the development of spectrophotometers from the earliest models to the latest microprocessor instruments with photodiode detection systems.