  Reactions between pairs of atoms are ubiquitous processes in chemistry and
physics. Quantum scattering effects on reactions are only observed at extremely
ultracold temperatures, close to the $s$-wave regime, with a small number of
partial waves involved. At higher temperatures, the different phases associated
with the centrifugal barriers of different partial waves average-out quantum
interference to yield semi-classical reaction rates. Here we use quantum-logic
to experimentally study resonant charge-exchange reactions between single cold
pairs of neutral $^{87}$Rb atoms and optically-inaccessible $^{87}$Rb$^{+}$
ions far above the $s$-wave regime. We find that the measured charge-exchange
rate is greatly suppressed with respect to the semi-classical prediction. Our
results indicate for the first time that quantum interference persists and
effects reaction rates at very high temperatures, at least three orders of
magnitude higher than the ultracold $s$-wave regime.
