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Register a new userRecovery of a SINIS turnstile accuracy in a strongly non-equilibrium regime
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We perform a theoretical study of non-equilibrium effects in charge transport through a hybrid single-electron transistor based on a small normal metal (N) island with the gate-controlled number of electrons, tunnel-coupled to voltage-biased superconducting (S) electrodes (SINIS). Focusing on the turnstile mode of the transistor operation with the gate voltage driven periodically, and electrons on the island being out of equilibrium, we find that the current quantization accuracy is a non-monotonic function of the relaxation rate $Gamma_{mathcal{F}}$ of the distribution function $mathcal{F}(epsilon)$ on the island due to tunneling, as compared to the drive frequency $f$, electron-electron $1/tau_{ee}$ and electron-phonon $1/tau_{eph}$ relaxation rates. Surprisingly, in the strongly non-equilibrium regime, $fgg Gamma_{mathcal{F}}ggtau_{ee}^{-1},tau_{eph}^{-1}$, the turnstile current plateau is recovered, similarly to the ideal equilibrium regime, $tau_{eph}^{-1}gg Gamma_{mathcal{F}}$. The plateau is destroyed in the quasiequilibrium regime when the electron-electron relaxation is faster than tunneling.
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We consider a hybrid single-electron transistor (SET) constituted by a gate-controlled normal-metal island (N) connected to two voltage-biased superconducting leads (S) by means of two tunnel junctions (S-I-N-I-S), operated as a turnstile. We show that the exchange of photons between this system and the high-temperature electromagnetic environment where it is embedded enhances Andreev reflection, thereby limiting the single-electron tunneling accuracy.
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Quasiparticle (qp) poisoning is a major issue that impairs the operation of various superconducting devices. Even though these devices are often operated at temperatures well below the critical point where the number density of excitations is expected to be exponentially suppressed, their bare operation and stray microwave radiation excite the non-equilibrium qps. Here we use voltage-biased superconducting junctions to demonstrate and quantify qp extraction in the turnstile operation of a superconductor-insulator-normal metal-insulator-superconductor single-electron transistor. In this operation regime excitations are injected into the superconducting leads at a rate proportional to the driving frequency. We reach a reduction of density by an order of magnitude even for the highest injection rate of $2.4times 10^8$ qps per second when extraction is turned on.
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