A major challenge for quantum cryptography is the ____________ problem, which deals with maintaining coherence of quantum states in a practical computing environment.

The major challenge in quantum cryptography is the Decoherence problem. Decoherence refers to the loss of coherence of quantum states in a practical computing environment. Maintaining the delicate quantum states is challenging due to interactions with the external environment, leading to errors and loss of quantum information. Addressing the decoherence problem is critical for the development and practical implementation of quantum cryptographic systems.__________________________________________________