Emergence of a long-lived collective state in multi-emitter systems via balanced cavity dissipation

Controlling atom–photon interactions is essential for exploring fundamental quantum light–matter physics and advancing quantum technologies. Since Dicke’s pioneering work, collective phenomena in quantum emitters have been widely studied. In particular, superradiance has been demonstrated across various platforms, including atomic, superconducting, and semiconductor systems. However, these bright collective states rapidly decay to the ground state, limiting their usefulness for quantum information processing. In contrast, long-lived subradiant states hold significant promise as quantum resources but have remained less explored due to their inherently dark-state nature.

Here, we demonstrate a long-lived subradiant state among multiple quantum emitters coupled to a directional low-Q cavity. In a tailored photonic environment that engineers cavity dissipation, emitter-field coupling strength, and incoherent pumping, we realize a steady-state subradiant population in two cavity-coupled quantum dots. While previous approaches relied on precise control of the phase of a laser or the distance of emitters in pulsed schemes, we achieve steady-state subradiance by optimizing incoherent, dissipative excitation and relaxation dynamics in an open quantum system.

The emergence of a long-lived collective state leads to remarkably large photon bunching (g⁽²⁾(0)>8). Such giant bunching has only been theoretically predicted and recognized as a key signature of steady-state subradiance. Our cavity dissipation-mediated approach provides a powerful route to generating and exploiting long-lived entangled states in quantum emitters, opening new possibilities for scalable quantum information technologies.