Thermodynamics of the Ramsey Zone

We studied the thermodynamic properties such as the entropy, heat ([Formula: see text]), and work ([Formula: see text]) rates involved when an atom passes through a Ramsey zone, which consists of a mode field inside a low-quality factor cavity that behaves classically, promoting rotations on the atomic state. Focusing on the atom, we show that [Formula: see text] predominates when the atomic rotations are successful, maintaining its maximum purity as computed by the von Neumann entropy. Conversely, [Formula: see text] stands out when the atomic state ceases to be pure due to its entanglement with the cavity mode. With this, we interpret the quantum-to-classical transition in light of the heat and work rates. Besides, we show that, for the cavity mode to work as a Ramsey zone (classical field), several photons (of the order of [Formula: see text]) need to cross the cavity, which explains its classical behavior, even when the inside average number of photons is of the order of unity.