0000000000023538

AUTHOR

Jani Kivioja

showing 3 related works from this author

Turnstile behaviour of the Cooper-pair pump

2003

We have experimentally studied the behaviour of the so-called Cooper pair pump (CPP) with three Josephson junctions, in the limit of small Josephson coupling EJ < EC. These experiments show that the CPP can be operated as a traditional turnstile device yielding a gate-induced current 2ef in the direction of the bias voltage, by applying an RF-signal with frequency f to the two gates in phase, while residing at the degeneracy node of the gate plane. Accuracy of the CPP during this kind of operation was about 3% and the fundamental Landau-Zener limit was observed to lie above 20 MHz. We have also measured the current pumped through the array by rotating around the degeneracy node in the ga…

PhysicsJosephson effectCondensed matter physicsCondensed Matter - Mesoscale and Nanoscale PhysicsCondensed Matter - SuperconductivityPhase (waves)FOS: Physical sciencesBiasingCondensed Matter PhysicsCondensed Matter::Mesoscopic Systems and Quantum Hall EffectAtomic and Molecular Physics and OpticsSuperconductivity (cond-mat.supr-con)TurnstileNode (physics)Mesoscale and Nanoscale Physics (cond-mat.mes-hall)QuasiparticleGeneral Materials ScienceCooper pairDegeneracy (mathematics)
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Direct measurement of the electron‐phonon relaxation rate in thin copper films

2004

We have used normal metal-insulator-superconductor (NIS) tunnel junction pairs, known as SINIS structures, for ultrasensitive thermometry at sub-Kelvin temperatures. With the help of these thermometers, we have developed an ac-technique to measure the electron-phonon (e-p) scattering rate directly, without any other material or geometry dependent parameters, based on overheating the electron gas. The technique is based on Joule heating the electrons in the frequency range DC-10 MHz, and measuring the electron temperature in DC. Because of the nonlinearity of the electron-phonon coupling with respect to temperature, even the DC response will be affected, when the heating frequency reaches th…

PhysicsCondensed Matter - Mesoscale and Nanoscale PhysicsCondensed matter physicsCondensed Matter - SuperconductivityFOS: Physical scienceschemistry.chemical_element02 engineering and technologyElectron021001 nanoscience & nanotechnology01 natural sciencesCopperSuperconductivity (cond-mat.supr-con)chemistryTunnel junctionScattering rateMesoscale and Nanoscale Physics (cond-mat.mes-hall)0103 physical sciencesElectron temperature010306 general physics0210 nano-technologyJoule heatingFermi gasOverheating (electricity)physica status solidi (c)
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Response time of a thermometer based on normal metal–insulator–superconductor (NIS) tunnel junctions

2003

Abstract We have measured the thermal response of a superconductor–normal metal–superconductor (SINIS) tunnel junction structure at substrate temperature ∼60 mK by directly heating the electron system in the normal metal island. In our structure, we find the response time is determined by the electron–phonon coupling in the electron temperature range 300– 600 mK . By using AC heating, the cut-off frequency caused by this response time has been measured, showing that SINIS structures operate as a thermometer up to a few MHz in this temperature range.

SuperconductivityMaterials scienceCondensed matter physicsResponse timeSubstrate (electronics)Atmospheric temperature rangeCondensed Matter PhysicsAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsTunnel junctionCondensed Matter::SuperconductivityThermometerThermalElectron temperaturePhysica E: Low-dimensional Systems and Nanostructures
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