Quantum computing is an innovative and novel approach to performing computations using physical properties of quantum mechanics, namely superposition and entanglement than classical systems. Quantum computing for blockchain provides stronger security and efficiency for distributed systems with the help of quantum-immune cryptographic methods. In this book chapter, the author presents the fundamental understanding of quantum computing and blockchain in the context of security in post-quantum environments, and how the two technologies can be adopted to address the challenge. It draws the weakness of classical cryptography and the quantum honest verifier model; moreover, it also introduces quantum communication like Quantum Key Distribution (QKD) to enhance the blockchain networks. This chapter also briefs on a post-quantum cryptographic algorithm that guarantees the protection of data besides ensuring system security. Proposed quantum protocols supplementary to consensus algorithms and safe smart contacts are described to demonstrate their possibilities for improving blockchain technologies. Moreover, this chapter discusses the limitations of adopting quantum technologies, including scalability and implementation issues, as well as emerging prospects for advancement. Thus, the presented chapter acts as an orientation to the concepts that underlie the employment of quantum protocols in construction of the safe, progressive blockchain networks.