Flying-Qubit Control of Path Integrals

The flying-qubit control is crucial for quantum information science and technology, and holds significant research importance. This article presents a model for controlling extendable multichannel multiphoton flying qubits when driven simultaneously by non-vacuum inputs and classical fields. The model can be used to describe the generation, reception, conversion, routing, feedback, measurement, and networking of flying qubits with arbitrary wave packets. Unlike traditional approaches that utilize auxiliary systems to represent equivalent non-vacuum inputs, this model is based only on temporal photon number state vectors and quantum stochastic differential equations. Compared with existing relevant conclusions, this model is analogous to path integrals and possesses transient analysis and scalability, which are very useful for understanding and applying quantum control.