International Workshop on Superconducting Nano-Electronics Devices: Sned Proceedings, Naples, Italy,

Thisvolumereportsthemajorpartofthescientificcontributionsofthefirstinternational workshoponSuperconductingNano-ElectronicsDevices(SNED)heldinNapoli, Italy, at theendofMay2001. Theaimoftheworkshopwastofocusonrecentexperimentalandtheoreticalresultsin thefieldofsuperconductingnano-electronicsdevices. Itcombinedphysicswithpresent andfuturetechnologicalapplications: bothfundamentalandappliedaspectswerecovered. SpecialemphasiswasgiventoquantumcoherenceandcomputationusingsmallJosephson junctions, noiseinultrasensitivenanodevicesandpossibilitiesofmakinguseofsupercon- ductivityinvariouson-chipdevices. Withtheseattributesandwithrecognizedinvited speakersintheirspecialtiestheworkshopmanagedtobringtogetheracollectionof scientistsfromnearbybutdistinctresearchcommunities. Thiswaytheatmosphereofthe workshopbecameveryopenanddiscussionswerelivelybothduringandoutsidethe sessions. Thisfreshdiscussionhopefullygaveeveryparticipantalotofnewideasfor furtherworkbackintheirhomeinstitutes. OneofthecentraltopicsintheworkshopwastheuseofdifferentJosephsonjunction configurationsasimplementationsofquantumbits. Atthetimeoftheworkshopwewere justwaitingforthesecondwaveofbreakthroughsinthisfield: theresultsemergingfrom theparticipatinglaboratoriesoftheworkshopjustatthetimeofthewritingofthispreface perhapsalsoprovetheusefulnessofourworkshop. Anotherfocuswasonvarioustopicsrelatedtoultrasensativedetectors. Theybring quantumlimitationstoapplications, andmanydeviceconceptsareresultsofunderstanding fundamentalandexcitingphenomenainsuperconductivity. Noiseandon-chipcooling wereexplicitlydiscussedinthedetectorsessionsaswell. ThechoiceofthelocationrecognizestheroleandthetraditionsofNapoliespeciallyin thefieldofmacroscopicquantumcoherence, oneofthemainissuesoftheworkshop. It furtherguaranteedtheparticipantsastimulatingatmosphereatthemeeting. Inconclusion, wewishtothanktheIstitutoItalianopergliStudiFilosofici, theIstituto diCiberneticadelConsiglioNazionaledelleRicerche, theUniversityofJyviiskylii, the IstitutoNazionalediFisicaNucleare, theIstitutoNazionalediFisicadellaMateria, the DipartimentoScienzeFisiche, andtheRettoratodell'UniversitadiNapoli"FedericoII" fortheirsupport. ThanksarealsoduetoAirLiquide, CRY, Nanoway, OxfordInstruments, andRaith. ThisinitiativeisintheframeoftheinternationalactivityofMQC2Association on"MacroscopicQuantumCoherenceandComputing. "WeareindebtedtoC. Granata v vi PREFACE and V. Coratoforscientificassistance, andtoF. Caiazzo, E. DeGrazia, andA. M. Mazzarellafortheirvaluableassistanceinallthetasksconnectedtotheorganizationofthe Workshop. WearealsogratefultoL. Longobardi, A. Monaco, S. Piscitelli, andS. Rombetto forhintsandhelpduringtheWorkshop. ThanksareduetoL. DeFelice, S. Luongo, and V. Sindonifortheorganizationofthesocialevent. J. Pekola B. Ruggiero P. Silvestrini CONTENTS QuantumNondemolitionMeasurementsofaQubit . D. V. Averin BayesianQuantumMeasurementofaSingle-Cooper-PairQubit 11 A. Korotkov lIfNoiseinJosephsonQubits 15 E. Paladino, L. Faoro, G. Falci, and R. Fazio SwitchingCurrentsandQuasi-ParticlePoisoningintheSuperconducting SingleElectronTransistor 25 P. Agren, J. Walter, V. Sch611mann, andD. B. Haviland JosephsonSystemsforQuantumCoherenceExperiments 33 V. Corato, C. Granata, L. Longobardi, M. Russo, B. Ruggiero, andP. Silvestrini SolidStateAnalogueofDoubleSlitInterferometer. . . . . . . . . . . . . . . . . . . . . . 43 K. Yu. Arutyunov, T. T. Hongisto, andJ. P. Pekola NoiseandMicrowavePropertiesofSET-Transistors. . . . . . . . . . . . . . . . . . . . . 53 M. Ejrnres, M. T. Sa