Electronic transport in nanostructures Thomas Ihn ETH Zrich

Electronic transport in nanostructures Thomas Ihn ETH Zürich FS 17

After this lecture you know and understand… • … how decoherence comes about • … how and why decoherence is related to entanglement • … how and why decoherence is related to measurement and information retrieval • … how noise can cause decoherence

Reading Chapter 21. 3: Controlled decoherence Chapter 14. 7: Decoherence See also: Chapters 14. 3, 14. 8, 15. 2

Quantum Interference phenomena in nanostructures Aharonov–Bohm effect Universal Conductance fluctuations Weak localization

Temperature dependent phase coherence time

Thermal decoherence in an AB interferometer Thermal dedecoherence in an Aharonov-Bohm interferometer

Quantum Interference phenomena in nanostructures Mach-Zehnder interferometer

Quantum Interference phenomena in nanostructures Fabry-Perot interferometer (QDs)

Quantum Interference phenomena in nanostructures Fano-effect A. C. Johnson, Phys. Rev. Lett. 93, 106803 (2004).

Interferometer-Detector arrangement Buks et al. , Nature 391, 871 (1998) the QPC detects the charge state of the QD Idea: Controlled decoherence in an Aharonov-Bohm interferometer

Generic interferometer–detector setup

Quantum point contact shot noise

Different interferometer–detector setup

Decoherence by QPC detector Buks et al. , Nature 391, 871 (1998) Controlled decoherence in an Aharonov-Bohm interferometer

Decoherence by partitioned edge state Sprinzak et al. , Phys. Rev. Lett. 84, 5820 (2000)

Decoherence by partitioned edge state Rohrlich et al. , PRL 98, 096803 (2007) Controlled decoherence in a Fabry-Perot interferometer