Frequency to power conversion by an electron turnstile

Direct frequency to power conversion (FPC), to be presented here, links both quantities through a known energy, like single-electron transport relates an operation frequency f to the emitted current I through the electron charge e as I = ef [1–6]. FPC is a natural candidate for a power standard resorting to the most basic definition of the watt, comprising a simple and elegant way to realize it [7]. In this spirit, single-photon emission and detection at known rates have been proposed and experimented as radiometric standard [8–15]. However, nowadays power standards are only traceable to electrical units with no alternative proposals in sight [7, 16–18]. In this letter, we demonstrate the feasibility of solid-state direct FPC using a SINIS (S = superconductor, N = normal metal, I = insulator) single-electron transistor (SET) accurately injecting N (integer) quasiparticles (qps) per cycle to both leads with discrete energies close to their superconducting gap ∆, even at zero drain-source voltage. Furthermore, the bias voltage plays an important role in the distribution of the power among the two leads, allowing for an almost equal injection N∆f to the two. We estimate that under appropriate conditions errors can be well below 1%.