  Spin squeezed states are a class of entangled states of spins that have
practical applications to precision measurements. In recent years spin
squeezing with one-axis twisting (OAT) has been demonstrated experimentally
with spinor BECs with more than 10^3 atoms. Although the noise is below the
standard quantum limit, the OAT scheme cannot reduce the noise down to the
ultimate Heisenberg limit. Here we propose an experimentally feasible scheme
based on optimized quantum control to greatly enhance the performance of OAT to
approach the Heisenberg limit, requiring only an OAT Hamiltonian and the use of
several coherent driving pulses. The scheme is robust against technical noise
and can be readily implemented for spinor BECs or trapped ions with current
technology.
