Quantum information and quantum phase transitions in atom–molecule conversion systems

Quantum phase transition is a fundamental physical phenomenon in a quantum many-body system. This work aims to explore the quantum phase transition in an atom–molecule conversion system through quantum information tools. We show that the ground state of the system undergoes significant changes in the quantum critical region, with both atomic number fluctuation and the quantum information embedded in the ground state exhibiting drastic alterations. As the rescaled phase transition parameter increases, the atomic state sharply transits into the molecular state in the critical region. Even for finite total number, the phase transition point can be accurately predicted through finite-size scaling laws. Our study confirms that the finite-size scaling analysis based on quantum coherence and quantum Fisher information is a reliable method for studying critical phenomena in the atom–molecule system from a quantum information perspective.