  When an atom is in an excited state, after some amount of time, it will decay
to a lower energy state emitting a photon in the process. This is known as
spontaneous emission. It is one of the three elementary light-matter
interactions. If it has not decayed at time $t$, then the probability that it
does so in the next infinitesimal time step $[t, t+\delta t]$, is
$t$-independent. So there is no preferred time at which to decay -- in this
sense it is a random process. Here we show, by carefully engineering this
light-matter interaction, that we can associate it with a clock, where the
matter constitutes the clockwork and the spontaneous emission constitutes the
ticking of the clock. In particular, we show how to realise the quasi-ideal
clock. Said clock has been proven -- in an abstract and theoretic sense -- to
be the most accurate clock permissible by quantum theory, with a polynomial
enhancement in precision over the best stochastic clock of the same size. Our
results thus demonstrate that the seemingly random process of spontaneous
emission can in actual fact, under the right circumstances, be the most regular
one permissible by quantum theory. To achieve this we use geometric features
and flux-loop insertions to induce symmetry and Berry phases into the
light-matter coupling. We also study the entropy the clock produces per tick
and show that it also possesses a quantum advantage over that generated from
the previously known semi-classical clocks in the literature.
