Experimental study on the principle of minimal work fluctuations

The central quantity in the celebrated quantum Jarzynski equality is e-beta W, where W is work and beta is the inverse temperature. The impact of quantum randomness on the fluctuations of e-beta 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 the two-point measurement of nonequilibrium work with single-shot readouts, we have conducted a direct experimental investigation of the relationship between the fluctuations of e-beta W and adiabaticity of nonequilibrium work protocols. It is observed that adiabatic processes minimize the variance of e-beta 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-beta 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.