We introduce an entanglement witness that identifies off-diagonal long-range order (ODLRO)—a distinctive form of entanglement—in systems containing both fermionic and bosonic particles. By analyzing the particle-hole reduced density matrices of each subsystem, the approach detects ODLRO independently in both fermionic and bosonic sectors and identifies when long-range order develops across the entire mixed-particle system. The witness also quantifies the magnitude of ODLRO within each particle type, revealing how fermionic and bosonic correlations combine to form the total entanglement of the system, including a bosonic condensation of particle-hole pairs driven by many-body correlations rather than particle statistics. Using the Lipkin-Meshkov-Glick spin model, we show how the transition from ODLRO localized to one particle type to ODLRO shared by both particle types captures the onset of collective entanglement in a mixed-particle environment, providing intriguing insight into systems where fermionic and bosonic correlations coexist.

Close

PrevNext

View figure in article

• Quantum entanglement
• Quasiparticles & collective excitations
• Density matrix methods