Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 5: Transporteigenschaften

HL 5.7: Vortrag

Montag, 8. März 2004, 11:45–12:00, H14

Quantum Dots as Quantum Bits — •Daniel Schröer¹, Andreas K. Hüttel¹, Stefan Ludwig¹, Werner Wegscheider², and Jörg Kotthaus¹ — ¹CeNS und Sektion Physik der LMU München — ²Institut für Angewandte und Experimentelle Physik der Universität Regensburg

We create lateral quantum dots by depleting the two-dimensional electron system of an AlGaAs/GaAs heterostructure with lithographically defined Schottky gates. The advantage of this lateral approach is the flexibility in number and orientation of leads and gates. Multiple quantum dots can be coupled capacitively or via tunnel barriers. The coupling strengths and the number of free charge carriers per dot are tuned by means of gate voltages. A double quantum dot is often regarded as an artificial molecule, as the discrete states of both dots split into molecular bonding and antibonding states. These form a two-level system that is applicable as a qubit for quantum information processing. The complexity of the molecular states increases with the number of free electrons per dot. Hence, we aim to reduce the dot sizes and integrate suitable tools to read out the number of charge carriers (e.g. a quantum point contact). The molecular states are probed by analysing the charging diagram of the system. In addition we will attempt to couple more than two quantum dots to study the interaction of several qubits. First results will be presented.