Circuit Knitting for Continuous-Variable Quantum States

Abstract: In finite-dimensional systems, circuit knitting can be used to simulate non-classical quantum operations using a limited set of resources. In this work, we extend circuit knitting techniques to infinite-dimensional quantum systems. We develop a general theoretical framework for simulating non-Gaussian states from the given set of available states. Also, we establish fundamental constraints with the no-go theorem on the circuit knitting of multi-mode Gaussian operations, by showing that the exact knitting with separable operations requires infinite sampling overhead. We further explore several applications of our theory, including simulation of approximate Fock states, GKP state generation, and cat-state amplification.