Quantum Computing 101: From Zero to Your First Circuit
Dr. Donovan
bloch sphere
1 course · 9 tutorials
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- intermediate
- 16 min read
Measurement, Decoherence and What the Bloch Sphere Cannot Show You
The Bloch sphere is a map with edges. This final part covers what measurement does to the arrow, why real qubits drift inside the ball, and why an entangled qubit has no arrow at all.
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- intermediate
- 15 min read
Rx, Ry and Rz: Reaching Any Point on the Bloch Sphere
Give a rotation a dial instead of a fixed angle and you can steer a qubit anywhere on the Bloch sphere with two gates. This is the Euler decomposition, and it is what your transpiler does to every circuit you run.
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- beginner
- 14 min read
Hadamard, S and T on the Bloch Sphere
The Hadamard gate is a half-turn about a diagonal axis, and S and T are partial twists about the vertical one. Seen on a live Bloch sphere, the H, S and T gates stop being matrices and start being furniture-moving.
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- beginner
- 13 min read
Pauli Gates as Rotations: X, Y and Z on the Bloch Sphere
Watch the X, Y and Z gates run on a live Bloch sphere. All three are half-turns around an axis, which explains why X flips a qubit, why Z appears to do nothing, and why applying any of them twice gets you back where you started.
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- beginner
- 12 min read
How to Read the Bloch Sphere
A guided tour of the Bloch sphere using a live simulator: what the poles, the equator and the two angles actually mean, and why two states with identical measurement odds can sit on opposite sides of the ball.
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- beginner
- 15 min
Qubits vs Classical Bits: The Key Differences
A side-by-side comparison of classical bits and qubits: what makes a qubit fundamentally different, what it can and cannot do, and common misconceptions.
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- beginner
- 11 min read
Visualizing Quantum Circuits and States in Qiskit
How to visualize quantum circuits, measurement histograms, statevectors, and Bloch sphere representations using Qiskit's built-in tools.
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- beginner
- 10 min read
What is a Qubit?
A plain-English explanation of qubits, what makes them different from classical bits and why that matters for computing.
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- intermediate
- 25 min read
Bloch Sphere Math: State Vectors to Rotations
The mathematics behind the Bloch sphere: how the angles θ and φ map to quantum state vectors, why single-qubit gates are rotations, and how to read any single-qubit state geometrically.