Superradiance in the breath of a virus

Room-temperature superradiance in hybrid biocompatible, virus-derived nanoparticles promises to surpass state-of-the-art coherent light sources for bioimaging. Recently, RT SR was observed from an icosahedral virus covalently labeled with hundreds of molecular chromophores in aqueous solution. Here, we investigate how the viral scaffold suppresses dephasing and sustains RT SR. By encapsulating a gold nanoparticle inside the virus, we use transient absorption spectroscopy to probe virus capsid acoustic phonons via the nanoparticle’s breathing mode. In addition to the gold vibration, we detect a reproducible feature at ~1 cm^-1 that was also observed as a slow modulation of the electronic-excited state population decay of the dye-decorated particles. Guided by modeling, we attribute this modulation in the SR virus to a long-lived ℓ=2 acoustic phonon of the capsid. This mode can act as a common bath that prevents faster decoherence and suppression of the SR transition. It may also help synchronize the emitters. Beyond introducing a new measurement method of the  acoustic phonon modes of viruses, this work highlights how long-lived global motions can be harnessed to design quantum biomaterials.