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A mesoscopic capacitor connected via a single spin polarized channel to a metallic contact exhibits a capacitance dominated by the sample specific level spectrum but exhibits a charge relaxation resistance that is universal and quantized at half a resistance quantum [1]. Together with the capacitance the charge relaxation resistance determines the RC-time of the capacitor. An experiment by Gabelli et al. [2] investigated in detail the capacitance and demonstrated the quantization of the charge relaxation resistance at half the resistance quantum. We demonstrate that the charge relaxation resistance is quantized not only in RPA but also if interactions [3] are treated in Hartree-Fock. On the other hand the charge relaxation resistance is very sensitive to dephasing [4]. Recently Fève et al. [5] demonstrated that a quantum coherent capacitor subject to pulse cycles with amplitudes as large as an effective level separation and with a duration longer than the RC-time can be made to emit and reabsorb exactly one electron in each half cycle. This experiment [5] demonstrated quantized currents with pulse cycles in the GHz range. We provide theoretical predictions of the accuracy of the quantization and investigate the noise of this very fast single electron source [6]. Our results are important for future scientific and possible metrological applications of this source.
[1] M. Buttiker, H.Thomas, A. Prêtre, Phys. Lett. A 180, 364 (1993). [2] J. Gabelli et al., Science 313, 499 (2006). [3] S. E. Nigg, R. Lopez and M. Buttiker, Phys. Rev. Lett. 97, 206804 (2006). [4] S. E. Nigg and M. Buttiker, cond-mat/0709.3956 [5] G. Fève et al., Science 316, 1169 (2007). [6] M. Moskalets, P. Samuelsson and M. Buttiker, cond-mat/0707.1927 |
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