Nonequilibrium quasiparticles and 2e periodicity in single-Cooper-pair transistors.
نویسندگان
چکیده
We have fabricated single-Cooper-pair transistors in which the spatial profile of the superconducting gap energy was controlled by oxygen doping. The profile dramatically affects the switching current vs gate voltage curve of the transistor, changing its period from 1e to 2e. A model based on nonequilibrium quasiparticles in the leads explains our results, including the observation that even devices with a clean 2e period are "poisoned" by small numbers of these quasiparticles.
منابع مشابه
Charge transport in voltage-biased superconducting single-electron transistors.
Charge is transported through superconducting SSS single-electron transistors at finite bias voltages by a combination of coherent Cooper-pair tunneling and quasiparticle tunneling. At low transport voltages the effect of an “odd” quasiparticle in the island leads to a 2e-periodic dependence of the current on the gate charge. We evaluate the I − V characteristic in the framework of a model whic...
متن کاملControlled Single-Cooper-Pair Charging Effects in a Small Josephson Junction Array
We report on measurements of single-Cooper-pair charging effects in small Josephson junction arrays, and the experimental techniques that were used. We succeeded in having complete control over the array’s electrostatic parameters; offset charges were accurately compensated, and the poisoning of 2e-periodic effects by quasiparticles was circumvented. This allowed for a controlled study of the a...
متن کاملEffect of measurement on the periodicity of the Coulomb staircase of a superconducting box.
We report on the effect of the backaction of a single Cooper pair transistor electrometer (E) on the charge state of a superconducting box (B). The charge is e periodic in the gate bias of B when E is operated near voltages 2 Delta/e or 4 Delta/e. We show that this is due to quasiparticle poisoning of B at a rate proportional to the number of quasiparticle tunneling events in E per second. We a...
متن کاملac Josephson effect and resonant Cooper pair tunneling emission of a single Cooper pair transistor.
We measure the high-frequency emission of a single Cooper pair transistor (SCPT) in the regime where transport is only due to tunneling of Cooper pairs. This is achieved by coupling on chip the SCPT to a superconductor-insulator-superconductor junction and by measuring the photon assisted tunneling current of quasiparticles across the junction. This technique allows a direct detection of the ac...
متن کاملA ug 2 00 5 Quantum nano - electromechanics with electrons , quasiparticles and Cooper pairs : effective bath descriptions and strong feedback effects
Using a quantum noise approach, we discuss the physics of both normal metal and superconducting single electron transistors (SET) coupled to mechanical resonators. Particular attention is paid to the regime where transport occurs via incoherent Cooper-pair tunneling (either via the Josephson quasiparticle (JQP) or double Josephson quasiparticle (DJQP) process). We show that, surprisingly, the b...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Physical review letters
دوره 92 6 شماره
صفحات -
تاریخ انتشار 2004