Collective Charge of Bosons (CCB)

The concept of electric charge is traditionally associated with elementary fermionic particles such as electrons. In contrast, bosonic quasiparticles like photons, magnons, and phonons are usually regarded as electrically neutral. Here we propose that a macroscopic occupation of a bosonic mode can give rise to an emergent collective charge, denoted as Qm_collective. We formulate a theoretical framework based on the many-body wavefunction of a Bose–Einstein condensate and show that the collective charge can be expressed as the expectation value of the total charge operator over the condensate state. When the number of bosons in the condensate becomes large, the collective charge tends to a finite value even though each individual boson remains neutral. We discuss possible experimental platforms for observing this effect, including photon condensation in microcavities, polariton condensates in semiconductor microstructures, and acoustic phonon condensates in nanomechanical systems. The emergence of a collective charge in bosonic systems opens a new avenue for investigating quasiparticle interactions, non-linear optical phenomena, and the design of novel quantum devices with controllable charge properties.