Transient quantum device simulations and the Wigner distribution function

The time dependent Wigner distribution function has been discussed as a key tool for the design of quantum devices in complex systems, such as high-speed clocks. The issues that need to be addressed for this to be successful are the ones that have always faced those performing device simulations. These include, dissipation, the role of contacts/boundaries, the form of the external circuit/transmission line, noise, hysteresis, as well as peculiarities associated with differencing. Each of these issues is reviewed within the context of the transient response of barrier devices to repetitive time dependent voltage pulses. Additionally, since the response of a device to repetitive disturbances is a key measure of its speed, in that the internal device capacitance is a component of the computation, we are also able to assess those factors that affect device performance. In particular the device response to the amplitude of the excitation, as well as its mean value, are addressed.