Generalized measurements may allow the control of its invasiveness on the
quantum system interpolating from a very weak to strong projective action. Such
a measurement can fuel a quantum heat engine or extract work depending on the
system-meter interaction. Here, we performed a proof-of-concept experiment
using Nuclear Magnetic Resonance techniques to investigate a spin quantum heat
engine driven by non-selective generalized (weak) measurements without feedback
control. Our prototype of a quantum thermal device operates with a measurement
protocol and a single heat bath. The protocol is composed of two non-selective
measurement channels with variable measurement strengths, one dedicated to
fueling the device (analogous to a hot heat source) and the other committed to
work extraction. The experimental results highlight that this kind of quantum
thermal device can reach unit efficiency with maximum extracted power by
fine-tuning of the measurement strengths.Comment: 8 pages, 6 figure