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Quantum random number generator

As explained in Real-World Cryptography

A quantum random number generator is a device or system that obtains unpredictable random values from quantum measurement outcomes.

A quantum random number generator (QRNG) obtains random values by measuring quantum states. A particle such as a photon is placed in superposition, where possible states coexist, and measurement randomly produces one observed state. section 14.1.1

The basic idea follows three steps:

  • Set particles such as photons into a superposed state. section 14.1.1
  • Measure the particles; measurement forces an outcome rather than leaving the state unresolved. section 14.1.1
  • Use the randomly observed outcomes as random numbers, giving cryptographers a physical source of unpredictability. section 14.1.1

Why the idea feels strange

The Schrödinger’s cat thought experiment gives an everyday-scale analogy: a system is described as having multiple possible states until observation. QRNGs use the smaller-scale quantum behavior itself rather than a cat or a thought experiment. section 14.1.1

How Real-World Cryptography covers it

How deep it goes
Explains superposition, measurement, and photon-based operation, but does not detail device engineering or post-processing.
Examples
Uses photons as operating particles and Schrödinger’s cat as an analogy for unresolved quantum states.
What it assumes
Introduces qubits and superposition by contrasting them with ordinary bits.
What you can do after
Understand how quantum superposition and measurement can supply unpredictable random values.
How it connects
Connects quantum mechanics with qubits, superposition, measurement, and cryptography.
Cover of Real-World Cryptography
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.