  We develop a theoretical model to describe the dissipative dynamics of
singlet-triplet qubits in GaAs quantum dots. Using the concurrence
experimentally obtained [M. D. Shulman et al., Science 336, 202 (2012)] as a
guide, we found that each logical qubit fluctuates under the action of a random
telegraph noise (RTN) that simulates the $1/f^\alpha$ noise. We also study the
dynamics of concurrence as a function of the amplitude of the RTN, the
correlation time of the RTN, the preparation time of states, and the two-qubit
coupling. Furthermore, we show that the two-qubit coupling together with the
preparation time strongly affect the entanglement dissipative dynamics and both
physical quantities can be employed to enhance the entanglement between
singlet-triplet qubits.
