  Spin-orbit coupling (SOC) can give rise to interesting physics, from spin
Hall to topological insulators, normally in condensed matter systems. Recently,
this topical area has extended into atomic quantum gases in searching for
artificial/synthetic gauge potentials. The prospects of tunable interaction and
quantum state control promote neutral atoms as nature's quantum emulators for
SOC. Y.-J. Lin {\it et al.} recently demonstrated a special form of the SOC
$k_x\sigma_y$: which they interpret as an equal superposition of Rashba and
Dresselhaus couplings, in bose condensed atoms [Nature (London) \textbf{471},
83 (2011)]. This work reports an idea capable of implementing arbitrary forms
of SOC by switching between two pairs of Raman laser pulses like that used by
Lin {\it et al.}. While one pair affects $k_x\sigma_y$ for some time, a second
pair creates $k_y\sigma_y$ over other times with Raman pulses from different
directions and a subsequent spin rotation into $\pm k_y\sigma_x$. With
sufficient many pulses, the effective actions from different durations are
small and accumulate in the same exponent despite that $k_x\sigma_y$ and $\pm
k_y\sigma_x$ do not commute. Our scheme involves no added complication, and can
be demonstrated within current experiments. It applies equally to bosonic or
fermionic atoms.
