An Overview of Josephson Junctions Based QPUs

Quantum processing units (QPUs) based on superconducting Josephson junctions promise significant advances in quantum computing. However, they face critical challenges. Decoherence, scalability limitations, and error correction overhead hinder practical, fault-tolerant implementations. This paper investigates these issues by exploring both fundamental quantum phenomena and practical engineering challenges. We analyze key quantum mechanical principles such as superposition, entanglement, and decoherence that govern the behavior of superconducting qubits. We also discuss quantum tunneling, Cooper pair formation, and the operational mechanics of Josephson junctions in detail. Additionally, we present a comparative analysis with alternative architectures, including ion trap and photonic systems. This comparison highlights the unique advantages and trade-offs of Josephson junction-based QPUs. Our findings emphasize the critical role of material innovations and optimized control techniques. These advances are essential for mitigating noise and decoherence and for realizing robust, scalable quantum computing.