  In this paper, we develop a system identification algorithm to identify a
model for unknown linear quantum systems driven by time-varying coherent
states, based on empirical single-shot continuous homodyne measurement data of
the system's output. The proposed algorithm identifies a model that satisfies
the physical realizability conditions for linear quantum systems, challenging
constraints not encountered in classical (non-quantum) linear system
identification. Numerical examples on a multiple-input multiple-output optical
cavity model are presented to illustrate an application of the identification
algorithm.
