Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 29: Transport: Quantum Dots, Wires, Point Contacts 3 (jointly with HL)

TT 29.5: Invited Talk

Tuesday, March 12, 2013, 10:30–11:00, H20

Nano-Conductors as Measurement Devices and Driving Sources — •Sigmund Kohler — Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain

The capacitive coupling between electrically isolated nano-circuits bears a wealth of novel transport effects. One prominent realization is the coupling of a quantum dot to a quantum point contact, where the latter acts as charge monitor. Most interesting is the backaction of the point contact to quantum superpositions in the measured system and the decoherence induced in this way. For example, it has been predicted that, despite decoherence, a charge monitor may be used for qubit phase readout with good fidelity [1]. Moreover, a point contact may act upon a double or triple quantum dot not only as detector or decoherence source, but may also impose useful non-equilibrium driving and thereby, e.g., induce a pump current. This effect leaves its fingerprints in the charging diagram of double quantum dots [2] and in the full-counting statistics [3]. If the point contact is replaced by a double quantum dot, coherent tunnel oscillations in the latter may induce phenomena known from ac-driven transport.
[1] C. Kreisbeck and S. Kohler, PRB 81, 125404 (2010)
[2] M. Stark and S. Kohler, EPL 91, 20007 (2010)
[3] R. Hussein and S. Kohler, PRB 86, 115452 (2012)