Journal
Long-form notes, Qiskit experiments, and applied optimization thinking.
A step-by-step distinction between coherence, decoherence and wavefunction collapse. Starting from a single electron with no definite pre-measurement path, the note shows how interaction with an environment creates entanglement, why orthogonal environmental states suppress interference, why decoherence does not select one outcome, and why this leads to the quantum measurement problem.
Read note →A key conceptual obstacle in understanding coherence is the assumption that because there is only one electron, it must always occupy one definite position and follow one definite path. Quantum mechanics separates these ideas: there can be one electron while its quantum state does not assign it one definite position before measurement.
Read note →Why does measuring which slit an electron passes through destroy interference? The answer is not human observation or the electron somehow noticing a detector. A physical interaction correlates the electron's paths with different detector states. The overlap between those detector states directly controls the surviving interference.
Read note →The double-slit experiment becomes genuinely quantum when electrons are sent one at a time. A spread of detector hits alone does not prove wave behavior; the crucial evidence is interference between probability amplitudes associated with alternative paths. This note follows the questions of what interferes, where negative phase comes from, whether one electron involves both paths, and what happens when we measure which slit it passes through.
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