We have investigated coherent time evolution of pseudo-molecular states of an
isolated (leadless) silicon double quantum-dot, where operations are carried
out via capacitively-coupled elements. Manipulation is performed by short
pulses applied to a nearby gate, and measurement is performed by a
single-electron transistor. The electrical isolation of this qubit results in a
significantly longer coherence time than previous reports for semiconductor
charge qubits realized in artificial molecules.Comment: 4 journal pages, 4 figures, Lette