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Superconducting Contacts beyond the Tunneling Limit
Published in Andrei D. Zaikin, Dmitry S. Golubev, Dissipative Quantum Mechanics of Nanostructures, 2019
Andrei D. Zaikin, Dmitry S. Golubev
Finally, we observe that Eq. (17.85), up to a numerical factor of order one, coincides with the corresponding results for τφ already derived in Chapters 14–16 from the analysis of the Andreev conductance of NS structures and of the weak localization correction to the conductance of normal metals. This agreement again illustrates the universality of the phenomenon of low-temperature quantum decoherence by electron–electron interactions, which can be observed in a variety of normal and hybrid NS structures. An important peculiar feature of our present situation is that unlike in Chapters 14–16, here we address non-dissipative electron transport demonstrating that quantum dephasing of Cooper pairs may occur exactly in the equilibrium ground state.
Counteracting quantum decoherence with optimized disorder in discrete-time quantum walks
Published in Journal of Modern Optics, 2019
Quantum state decoherence occurs as the wavefunction of a quantum system is collapsed, either entirely or partially, by energy dissipation into the environment or by the disclosure of its state information. Typical examples of quantum decoherence include the spontaneous decay in two-level systems and the scattering loss during the propagation of entangled photons (1). On the other hand, disorder describes the disturbance of the system's wavefunction by the chaotic external degrees of freedom it is coupled to, such as inhomogeneous chemical potential in a photosynthetic network (2). While corresponding to different mechanisms, both decoherence and disorder deteriorate the performance of quantum systems. In light of their prevalence in practice, there have been extensive efforts to address each of them, e.g. by applying high magnetic fields and error correction (3,4).