We analyze the shot noise in a voltage biased superconducting quantum point contact. Results are presented for the single channel case with arbitrary transmission. In the limit of very low transmission it is found that the effective charge, defined from the noise-current ratio, exhibits a steplike behavior as a function of voltage with well-defined plateaus at integer values of the electronic charge. This multiple charge corresponds to the transmitted charge in a multiple Andreev reflection (MAR) process. This effect gradually disappears for increasing transmission due to interference between different MAR processes.We analyze the shot noise in a voltage biased superconducting quantum point contact. Results are presented for the single channel case with arbitrary transmission. In the limit of very low transmission it is found that the effective charge, defined from the noise-current ratio, exhibits a steplike behavior as a function of voltage with well-defined plateaus at integer values of the electronic charge. This multiple charge corresponds to the transmitted charge in a multiple Andreev reflection (MAR) process. This effect gradually disappears for increasing transmission due to interference between different MAR processes.

arXiv:cond-mat/9812175Physical Review LettersMay 17, 1999102 citations

Quantum Noise and Mutiple Andreev Reflections in Superconducting Contacts

A. Martín‐Rodero, Juan Carlos Cuevas, A. Levy Yeyati +4 more

Springer eBooksJan 1, 20030 citations

Supercurrent Noise in Quantum Point Contacts

D. V. Averin, H. T. Imam

Spectral density of current fluctuations in a short ballistic superconducting quantum point contact is calculated for arbitrary bias voltages $V$ . Contrary to a commonly held view that the supercurrent flow in Josephson junctions is a coherent process without fluctuations, we find extremely large current noise that is caused by the supercurrent coherence. At finite voltages, this noise can be qualitatively understood as the shot noise of the large charge quanta of magnitude $2\ensuremath{\Delta}/V$ equal to the charge transferred through the contact during one period of the Josephson oscillations.Spectral density of current fluctuations in a short ballistic superconducting quantum point contact is calculated for arbitrary bias voltages $V$. Contrary to a commonly held view that the supercurrent flow in Josephson junctions is a coherent process without fluctuations, we find extremely large current noise that is caused by the supercurrent coherence. At finite voltages, this noise can be qualitatively understood as the shot noise of the large charge quanta of magnitude $2\ensuremath{\Delta}/V$ equal to the charge transferred through the contact during one period of the Josephson oscillations.

arXiv:cond-mat/9511128Physical Review LettersMay 13, 1996106 citations

Full counting statistics for superconducting quantum point contacts

Henning Soller

The calculation of the full counting statistics (FCS) for quantum mechanical systems has attracted much attention in recent years. In this thesis the FCS for superconducting quantum point contacts have been calculated. Such quantum point contacts frequently occur in modern microelectronic devices, which exploit the special features of superconductors. The FCS for normal metal-superconductor and superconductor-superconductor contacts have been calculated using a generalized Keldysh formalism and the results have been compared to both experimental and theoretical results. The calculation of the FCS allows a precise understanding of the physical nature of charge transfer. Particularly doubled shot noise due to Andreev reflections was explained and the behaviour of the Josephson current for long measurement times was calculated. The obtained results are also valuable for the understanding of transport through quantum dots with superconducting leads.The calculation of the full counting statistics (FCS) for quantum mechanical systems has attracted much attention in recent years. In this thesis the FCS for superconducting quantum point contacts have been calculated. Such quantum point contacts frequently occur in modern microelectronic devices, which exploit the special features of superconductors. The FCS for normal metal-superconductor and superconductor-superconductor contacts have been calculated using a generalized Keldysh formalism and the results have been compared to both experimental and theoretical results. The calculation of the FCS allows a precise understanding of the physical nature of charge transfer. Particularly doubled shot noise due to Andreev reflections was explained and the behaviour of the Josephson current for long measurement times was calculated. The obtained results are also valuable for the understanding of transport through quantum dots with superconducting leads.

AV Akademikerverlag eBooksOct 1, 20130 citations

Spectral density of current fluctuations in a short ballistic superconducting quantum point contact is calculated for arbitrary bias voltages

V

. Contrary to a commonly held view that the supercurrent flow in Josephson junctions is a coherent process without fluctuations, we find extremely large current noise that is caused by the supercurrent coherence. At finite voltages, this noise can be qualitatively understood as the shot noise of the large charge quanta of magnitude $2\ensuremath{\Delta}/V$ equal to the charge transferred through the contact during one period of the Josephson oscillations.