  The Jarzynski equality (JE), which connects the equilibrium free energy with
non-equilibrium work statistics, plays a crucial role in quantum
thermodynamics. Although practical quantum systems are usually multi-level
systems, most tests of the JE were executed in two-level systems. A rigorous
test of the JE by directly measuring the work distribution of a physical
process in a high-dimensional quantum system remains elusive. Here, we report
an experimental test of the JE in a single spin-1 system. We realized
nondemolition projective measurement of this three-level system via cascading
high-fidelity single-shot readouts and directly measured the work distribution
utilizing the two-point measurement protocol. The validity of the JE was
verified from the non-adiabatic to adiabatic zone and under different effective
temperatures. Our work puts the JE on a solid experimental foundation and makes
the NV center system a mature toolbox to perform advanced experiments of
stochastic quantum thermodynamics.
