The Influence of Permafrost Soil Structure on Microbial Community Diversity and Abundance

Soil structure plays a critical role in shaping soil microbial communities, who directly influence biogeochemical cycling1–4. Although well-studied in temperate systems, the importance of physical structure on soil microbial community diversity, function, and overall activity in permafrost soils is largely unknown. I hypothesized that (1) decreases in pore connectivity would increase microbial diversity based on an expected inverse relationship between diversity and connectivity; (2) soil with an increased abundance of larger pores (\u3e 75 µm), which are uninhabitable because they are too large to sustain liquid water, will exhibit lower bacterial and archaeal abundance and (3) the surface area of ice inclusions, which represents potentially habitable space in the form of brine channels, will be positively correlated with the abundance of active microbes. To test these hypotheses, I analyzed eight permafrost cores from three distinct sites in Alaska. Fine scale heterogeneity in soil physical and biological characteristics was captured from triplicate subsamples per core. To quantify soil ice inclusions and pore architecture, I scanned permafrost at -10 ºC using X-ray Computed Tomography to maintain its structure. Following scanning, both DNA and RNA were extracted from the permafrost and analyzed via amplicon sequencing and quantitative PCR of the 16S region. I analyzed the total and active microbial community diversity, and abundance. I found that at a scanning resolution of 20 µm only macro-scale features (\u3e75 µm) could be quantified. Despite the limitation to the resolution, permafrost soil appears to share characteristics with temperate soils like the dominant pore size class (75-100 µm) and the positive relationship between total porosity and pore connectivity. I also found a negative relationship between macroporosity and microbial diversity, indicating that dispersal limitation in permafrost and past soil conditions may contribute to the spatial structure of microbial community diversity currently seen in permafrost. Additionally, soil structure did not influence the abundance of the active microbial community, indicating. I require finer scale structural and microbial data to disentangle any existing relationships. Gaining these insights could help us understand how soil physical structure acts to influence community structure in this extreme environment

Tunable joint measurements in the dispersive regime of cavity QED

Joint measurements of multiple qubits have been shown to open new possibilities for quantum information processing. Here, we present an approach based on homodyne detection to realize such measurements in the dispersive regime of cavity/circuit QED. By changing details of the measurement, the readout can be tuned from extracting only single-qubit to only multi-qubit properties. We obtain a reduced stochastic master equation describing this measurement and its effect on the qubits. As an example, we present results showing parity measurements of two qubits. In this situation, measurement of an initially unentangled state can yield with near unit probability a state of significant concurrence.Comment: 4 pages, 4 figure

Heisenberg-limited qubit readout with two-mode squeezed light

We show how to use two-mode squeezed light to exponentially enhance cavity-based dispersive qubit measurement. Our scheme enables true Heisenberg-limited scaling of the measurement, and crucially, is not restricted to small dispersive couplings or unrealistically long measurement times. It involves coupling a qubit dispersively to two cavities, and making use of a symmetry in the dynamics of joint cavity quadratures (a so-called quantum-mechanics-free subsystem). We discuss the basic scaling of the scheme and its robustness against imperfections, as well as a realistic implementation in circuit quantum electrodynamics.Comment: 5 pages, 4 figures, Supplemental Materia

Multiplexed Readout of Transmon Qubits with Josephson Bifurcation Amplifiers

Achieving individual qubit readout is a major challenge in the development of scalable superconducting quantum processors. We have implemented the multiplexed readout of a four transmon qubit circuit using non-linear resonators operated as Josephson bifurcation amplifiers. We demonstrate the simultaneous measurement of Rabi oscillations of the four transmons. We find that multiplexed Josephson bifurcation is a high-fidelity readout method, the scalability of which is not limited by the need of a large bandwidth nearly quantum-limited amplifier as is the case with linear readout resonators.Comment: 7 pages, 6 figures, and 31 reference

Le traitement des eaux usées

L'article présente brièvement l'état de l'épuration des effluents des collectivités en France et au Québec. Il souligne ensuite quelques changements importants intervenus depuis dix ans dans le monde grâce aux progrès de la recherche et qui pourraient marquer l'avenir.En France, 95 % des agglomérations de plus de 10 000 équivalents-habitants disposent d'une station d'épuration. Le rythme de construction a atteint 730 installations nouvelles dans l'année 1976 mais il est redescendu à moins de 300/an. Sur les 11 310 stations de plus de 200 équivalents-habitants recensées, 5 % réalisent seulement un traitement primaire et la moitié en nombre, représentant plus de 60 % de la capacité de traitement utilisent le procédé des boues activées.Les investissements à réaliser entre 1994 et 2005 pour satisfaire aux exigences de la directive européenne du 21 mai 1991 sont évalués à environ 36 milliards de francs français, correspondant à la création de capacités de traitement supplémentaires de 17 millions d'équivalents-habitants et à des améliorations plus ou moins importantes d'un grand nombre de stations existantes.Au Québec, la construction des stations d'épuration s'est faite essentiellement dans les années 80 et 90. Aujourd'hui, près de 80 % de la population est desservie par des installations d'épuration, soit environ 4,9 millions d'habitants pour un débit hydraulique de 5,3 millions de m3/j.Parmi les 450 ouvrages municipaux ceux des Communautés Urbaines de Montréal et de Québec représentent, à eux seuls, près de 60 % de la capacité installée.Les stations physico-chimiques, bien que peu nombreuses, sont les plus importantes (6 stations pour 2,28 millions d'habitants) suivies par les boues activées (40 stations pour 0,69 million d'habitants) et la biofiltration (9 stations pour 0,75 million d'habitants). Environ 320 stations, de dimension plus modeste utilisent des étangs aérés, desservant en moyenne une population de 3 500 habitants.Sur le plan de l'évolution des techniques, la décennie écoulée a vu apparaître ou se confirmer des évolutions qui marqueront sans doute profondément la conception et l'exploitation des stations d'épuration dans les années à venir : - l'objectif maintenant presque généralisé d'éliminer les nutriments azote et phosphore et le développement rapide des techniques correspondantes;- la prise de conscience de l'importance des flux polluants véhiculés par les eaux pluviales et un début d'adaptation des stations d'épuration;- le développement limité mais réel des traitements anaérobies qui ont survécu à la démobilisation des surlendemains de la crise énergétique;- le fort développement des systèmes d'épuration biologique à culture fixée et notamment des biofiltres;- l'apparition prometteuse des membranes dans les systèmes d'épuration biologique permettant d'envisager de nouveaux objectifs de traitement;- la prise en compte de la fiabilité des systèmes d'épuration avec un poids de plus en plus important par rapport aux performances de pointe- une vision plus intégrée de la prévention des pollutions tant dans l'industrie (technologies propres) que dans les agglomérations (gestion intégrée de l'ensemble réseau-station d'épuration).This paper provides a brief discussion of the state of municipal wastewater treatment in France and Quebec. It then presents some important changes that have developed over the last ten years in the world and their potential influence on the future.In France, 95% of towns of more than 10 000 residents have a wastewater treatment plant. Construction of new plants reached 730 installations in 1976, but has since declined to less than 300/year. Among 11 310 sites of more of 200 inhabitants, 5 % utilize only primary treatment and 50 % utilize the activated sludge process which represents 60 % of the treatment capacity.In order to satisfy the European directive of May 21st 1991, approximately 36 billion French Francs should be invested between 1994 and 2005. This investment represents new wastewater treatment facilities for 17 million people.In Quebec, construction of wastewater treatment plants occurred mainly during the 80's and 90's. Today, nearly 80 % of the population is served by wastewater treatment plants, which represent approximately 4,9 million residents. This accounts for a flow rate of 5,3 million cubic meters per day.Among 450 municipal treatment plants, those of the urban communities of Montreal and Quebec represent nearly 60 % of the total wastewater treatment capacity of Quebec.Physico-chemical treatment plants are the most significant (6 plants for 2,28 million residents) followed by activated sludge process plants (40 plants for 0,69 million residents) and plants using biofilter technologies (9 plants for 0,75 million residents). A total of approximately 320 small treatment plants, serving an average of 3 500 residents, use the aerated lagoon treatment.Over the past decade technological developments have resulted in an evolution that will modify the design and operation of wastewater treatment plants in the future:- the more widespread use of techniques developed for the elimination of nitrogen and phosphorus; - the realization of the importance of polluting charges transported by pluvial waters; the beginning of the resultant wastewater treatment plant adaptations; - the limited development of anaerobic treatments that have survived the energy crisis; - the valuable development of biological fixed-culture systems for wastewater treatment and most notably, the biofilters; - the appearance of promising membrane technology in wastewater treatment systems, which could facilitate the definition of new treatment objectives; - the consideration the global reliability of the wastewater treatment systems instead of only peak performance; - a more integrated vision for the prevention of pollution in industry (clean technologies) as well as in the domestic environment (integrated management of sewerage system and wastewater treatment plant

First-order sidebands in circuit QED using qubit frequency modulation

Sideband transitions have been shown to generate controllable interaction between superconducting qubits and microwave resonators. Up to now, these transitions have been implemented with voltage drives on the qubit or the resonator, with the significant disadvantage that such implementations only lead to second-order sideband transitions. Here we propose an approach to achieve first-order sideband transitions by relying on controlled oscillations of the qubit frequency using a flux-bias line. Not only can first-order transitions be significantly faster, but the same technique can be employed to implement other tunable qubit-resonator and qubit-qubit interactions. We discuss in detail how such first-order sideband transitions can be used to implement a high fidelity controlled-NOT operation between two transmons coupled to the same resonator.Comment: 15 pages, 5 figure

Quantum Heating of a nonlinear resonator probed by a superconducting qubit

We measure the quantum fluctuations of a pumped nonlinear resonator, using a superconducting artificial atom as an in-situ probe. The qubit excitation spectrum gives access to the frequency and temperature of the intracavity field fluctuations. These are found to be in agreement with theoretical predictions; in particular we experimentally observe the phenomenon of quantum heating

Quantum walks on circles in phase space via superconducting circuit quantum electrodynamics

We show how a quantum walk can be implemented for the first time in a quantum quincunx created via superconducting circuit quantum electrodynamics (QED), and how interpolation from quantum to random walk is implemented by controllable decoherence using a two resonator system. Direct control over the coin qubit is difficult to achieve in either cavity or circuit QED, but we show that a Hadamard coin flip can be effected via direct driving of the cavity, with the result that the walker jumps between circles in phase space but still exhibits quantum walk behavior over 15 steps.Comment: 8 pages, 4 figures, 2 table