Abstract
The central quantity in the celebrated quantum Jarzynski equality is e^-β W, where W is work and β is the inverse temperature. The impact of quantum randomness on the fluctuations of e^-β W and hence on the predictive power of the Jarzynski estimator is an important problem. Working on a single nitrogen-vacancy center in diamond and riding on an implementation of two-point measurement of non-equilibrium work with single-shot readout, we have conducted a direct experimental investigation of the relationship between the fluctuations of e^-β W and adiabaticity of non-equilibrium work protocols. It is observed that adiabatic processes minimize the variance of e^-β W, thus verifying an early theoretical concept, the so-called principle of minimal work fluctuations. Furthermore, it is experimentally demonstrated that shortcuts-to-adiabaticity control can be exploited to minimize the variance of e^-β W in fast work protocols. Our work should stimulate further experimental studies of quantum effects on the bias and error in the estimates of free energy differences based on the Jarzynski equality.