Bistable dynamical systems are widely employed to robustly encode classical bits of information. However, they owe their robustness to inherent losses, making them unsuitable to encode quantum ...information. Surprisingly, there exists a loss mechanism, known as two-photon dissipation, that provides stability without inducing decoherence. An oscillator exchanging pairs of photons with its environment is expected to reach macroscopic bit-flip times between dynamical states containing only a handful of photons. However, previous implementations have observed bit-flip times saturating in the millisecond range. In this experiment, we design a superconducting resonator endowed with two-photon dissipation, and free of all suspected sources of instabilities and inessential ancillary systems. We attain bit-flip times exceeding 100 s in between states containing about 40 photons. Although a full quantum model is necessary to explain our data, the preparation of coherent superposition states remains inaccessible. This experiment demonstrates that macroscopic bit-flip times are attainable with mesoscopic photon numbers in a two-photon dissipative oscillator.
Current implementations of quantum bits (qubits) continue to undergo too many errors to be scaled into useful quantum machines. An emerging strategy is to encode quantum information in the two ...meta-stable pointer states of an oscillator exchanging pairs of photons with its environment, a mechanism shown to provide stability without inducing decoherence. Adding photons in these states increases their separation, and macroscopic bit-flip times are expected even for a handful of photons, a range suitable to implement a qubit. However, previous experimental realizations have saturated in the millisecond range. In this work, we aim for the maximum bit-flip time we could achieve in a two-photon dissipative oscillator. To this end, we design a Josephson circuit in a regime that circumvents all suspected dynamical instabilities, and employ a minimally invasive fluorescence detection tool, at the cost of a two-photon exchange rate dominated by single-photon loss. We attain bit-flip times of the order of 100 seconds for states pinned by two-photon dissipation and containing about 40 photons. This experiment lays a solid foundation from which the two-photon exchange rate can be gradually increased, thus gaining access to the preparation and measurement of quantum superposition states, and pursuing the route towards a logical qubit with built-in bit-flip protection.
The construction, mode of operation and performance of the first full-scale biological denitrification plant in France, at Eragny are described. The system operates at 80 m3 per h and is designed to ...produce treated water containing less than 25 mg per litre of nitrate from a raw water with a nitrate content of 62-67 mg per litre, ethanol being dosed at a rate of 33 g per m3 of the pure compound as a carbon source. Denitrification was followed by final treatment in a Biocarbon activated carbon filter which ensured adequate reaeration of the water and oxidation of traces of nitrite formed during the first stage. Rates of nitrate removal, backwash and cycle times, and backwash water consumption figures are reported, indicating how the efficiency of the process has been improved in the light of operating experience over almost 3 years. (Full translation 34 pounds sterling).
En 2001, la consommation d'énergie des établissements de l'industrie agroalimentaire atteint 5,1 millions de tonnes équivalent-pétrole (tep). Elle affiche ainsi un léger ralentissement par rapport à ...2000 (- 0,8 pour cent) qui rompt avec la progression antérieure de 2 à 3 pour cent l'an. Cette évolution résulte en grande partie du net recul de la consommation de combustibles (- 3 pour cent tandis que celle de l'électricité reste relativement stable (- 0,4 pour cent). Dans un contexte persistant de hausse des prix des produits pétroliers et du gaz, la facture énergétique de 2001 continue à s'alourdir (+ 4 pour cent par rapport à 2000) et atteint 1,5 milliards d'euros. Elle est, pour un peu plus de la moitié, consacrée aux achats de combustibles. L'autoproduction d'électricité, d'origine thermique, représente près de 12 pour cent de la consommation brute d'électricité des établissements de l'industrie agroalimentaire. La consommation d'électricité a pratiquement doublé en une quinzaine d'années. Elle représente près d'un tiers de la consommation totale en 2001. Celle des combustibles progresse plus lentement avec toutefois des évolutions différentes selon la nature du combustible considéré. L'utilisation du gaz en particulier continue de se répandre au détriment du fioul. En effet, tandis que la part du gaz dans la consommation totale d'énergie est passée de 26 pour cent en 1985 à 45 pour cent en 2001, celle du fioul dans le même temps a décru de 36 pour cent à 12 pour cent. Les industries du lait, du sucre, de la viande, des produits amylacés et celle des aliments pour animaux de ferme (à cause des déshydratateurs de fourrages) sont à l'origine des deux tiers de la consommation d'énergie dans les IAA
