Postgraduate @ Aalto University
Tuesday June 28 – 14.45 BST
An electron turnstile for frequency-to-power conversion
Nanometric normal-metal islands coupled to superconducting leads through insulating tunnel junctions are suitable as single-electron turnstiles, when its excess charge is periodically driven through a capacitively coupled gate electrode. The superconducting leads extend the stability zone along the whole gate-voltage parameter space making it possible to create single-electron currents by only allowing one tunnelling event per cycle per junction [1]. In this device, electric charge is carried by superconducting excitations which are injected into the leads in each tunnelling event. These excitations are created close to the superconducting gap edge. Consequently, the energy current, that is, power injected to the leads is given by a simple frequency-to-power conversion relation, namely the superconducting energy gap times the driving signal frequency $\left( P=\Delta f\right)$. Such a simple relation enables this device as a candidate for a power standard, analogue to the frequency-to-current conversion of single-electron turnstiles. This is experimentally demonstrated [2] as a first proof-of-concept. The power production is shown to be possible even in the absence of particle current. Moreover, the dynamics of power repartition among both junctions is studied. Further improvements in the accuracy of the power emission are proposed.
[1] Pekola, J. P. Vartiainen, J. J. Möttönen, M. Saira, O-P. Meschke, M. Averin, D. Hybrid single-electron transistor as a source of quantized electric current. Nat. Phys. 4, 2007.
[2] Marín-Suárez, M. Peltonen, J. T. Golubev, D. S. Pekola, J. P. An electron turnstile for frequency-to-power conversion. Nat. Nanotechnol., 2022.