Superconductivity, in which electricity flows with zero resistance below some critical temperature, has a wide range of potential applications. Progress is hampered, however, by the need for impractically low temperatures. Cuprate superconductors, made from a type of copper oxide, hold the record for high superconducting temperature without the need for extreme pressure. Strong laser pulses can trigger transient superconductivity at even higher temperatures, though the underlying mechanism remains elusive. Using a new computational method, we explore what drives this phenomenon.

Tackling the theoretical side of this problem is challenging because of the strong correlations among electrons, coupling with phonons (quanta of lattice vibrations), as well as additional complications from the ultrafast laser. Our approach separates the electronic wave function, the phonon wave function, and the entanglement between them. This allows us to solve the dynamics of each component using different techniques and self-consistently evolve the entire wave function.

Consistent with recent experiments, our method finds that a pulse laser can enhance the strength of an unconventional pairing symmetry known as $d$-wave pairing, which manifests as an increase of electron Cooper pairs responsible for superconductivity. However, the pairing is not sustained over relatively long distances, indicating that the induced Cooper pairs are essentially local. Therefore, light-induced superconductivity may be of a fluctuating nature.

Our method will initiate various revolutionary opportunities in simulating nonequilibrium experiments, such as pump-probe and x-ray scattering, on strongly correlated materials. Our study also represents the first important step toward understanding ultrafast light-induced phenomena in correlated materials with evident lattice effects.