Developer's Guide to Quantum Computing: Qubits, Bloch Sphere, and Python Code

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A developer-focused tutorial series on quantum computing continues with Part 2, building on foundational concepts introduced in Part 1. The article explains qubits using the Bloch Sphere model, describing how a qubit can exist in any state on a conceptual globe, unlike classical bits restricted to two fixed poles. It introduces the Hadamard Gate as the key quantum operation that places a qubit into pure superposition, giving equal probability of measuring 0 or 1. The guide connects these concepts to real-world applications, specifically Quantum Key Distribution, where quantum states are used to generate theoretically unhackable encryption keys. Practical Python implementation is demonstrated using an open-source library called qkdpy, which simulates the BB84 quantum security protocol.

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