Finite-key interfering-or-not-interfering quantum key distribution without intensity modulation

incorporating a scheme without intensity modulation (IM), which circumvents the impulse correlation issue associated with IM. Based on the minimum smooth entropy, we derive the key rate for finite code lengths and estimate the phase bit error rate using a no-decoy state method. Simulation results show that the protocol achieves the maximum communication distance of 337 km with quantum bit error rate of approximately 0.36%. Moreover, the feasibility of using fewer phase plates (M = 6, 8) to realize discrete random phases in INI-QKD is also verified. Notably, the INI-QKD without IM exhibits significant advantages under polarization misalignment and phase mismatch conditions, reflecting greater adaptability to complex environments. By simplifying experimental setups and reducing the technical challenges, the INI-QKD without IM provides an alternative realization idea in the field of quantum communication.