Ultrafast melting and recovery of collective order in the excitonic insulator Ta2NiSe5

The layered chalcogenide Ta_{2}iSe_{5}has been proposed to host an excitonic condensate in its ground state, a phase that could offer a unique platform to study and manipulate many-body states at room temperature. However, identifying the dominant microscopic contribution to the observed spontaneous symmetry breaking remains challenging, perpetuating the debate over the ground state properties. Here, using broadband ultrafast spectroscopy...