Quantum Inverse Scattering Transform*

Nonlinear differential equations are notoriously challenging to solve, given their importance to understand a wide range of phenomena. Quantum computing proposes a new paradigm for solving complex problems by leveraging quantum mechanical phenomena. In order to surpass the possibilities of classical computing, quantum algorithms must be carefully designed to exploit such phenomena, typically in highly non-trivial ways. In this work, we present a quantum algorithm to solve certain types of nonlinear partial differential equations by introducing a quantum version of the inverse scattering transform. This method provides an analytical framework to solve certain types of nonlinear equations by breaking the problem into linear subproblems, ultimately yielding the exact solution. Here, we work with the Korteweg-De Vries equation and show that adapting this method to the quantum setting leads not only to a quantum algorithm with exponential (quadratic) speedup in the time (spatial) domain, but also to a classical method that is asymptotically better than more traditional methods. We will then highlight how this quantum technique may be applied to solve other nonlinear differential equations that can be tackled with the inverse scattering technique, and its limitations.