Time-dependent quantum transport behavior through T-shaped double quantumdots

Abstract

The time-dependent current flowing through a T-shaped double quantum dot istheoretically studied via nonequilibrium Green’s function methods. Quantum coherentringing or beats can appear in the transient current after a bias voltage is turned on or off,and their periods can be tuned by the pulse bias or the interdot coupling strength. In theweak interdot coupling case no quantum beat is observed and only quantumringing appears in the current, the frequency of which depends on the pulse bias.In the strong interdot coupling case, quantum beats appear in the current andtheir frequency depends on the interdot coupling strength. Quantum beats aresuppressed greatly by the large energy difference between the two quantum dots. Inaddition, quantum ringing and beats tend to disappear with increasing temperature.