  If a measurement process is regarded as an irreversible process, then by
Second law of thermodynamics the entropy should increase after any measurement
process. By the same spirit a quantum system undergoing repeated measurement
should show strong irreversibility leading to entropy production. On the
contrary we show that in quantum Zeno effect setting the entropy of a quantum
system decreases and goes to zero after a large number of measurements. We
discuss the entropy change under continuous measurement model and show that
entropy can decrease if we use a more accurate measuring apparatus.
