Glossary
Background radiation
Low-level ionizing radiation that is continually present in the environment from natural and human-made sources.
Byte
A group of eight bits. In the Quantum Randomness experiment, each byte is displayed as an integer value from 0 through 255.
Complete period
A day, week, or month that satisfies the measurement-coverage rules used for long-term averages. For Natural Radiation, a day requires at least 99% of its expected one-second live samples; a week or month requires every included day to be complete.
Conditioning
Processing applied to raw physical measurements to reduce bias and produce a more uniform random-bit stream. Conditioning does not create randomness; it reshapes data derived from the underlying physical source.
Count
One electrical pulse recorded by the radiation detector. A count indicates a detected interaction, not a direct measurement of radiation dose.
Counts per minute (CPM)
The number of detector counts recorded during one minute. CPM depends on the detector, its sensitivity, its surroundings, and the radiation field.
Decay time
The time at which a particular unstable nucleus decays. For an individual nucleus it is unpredictable; only the probability of decay over an interval can be specified. In the Schrödinger’s Cat experiment, this time is simulated from QRNG output.
Detector
Hardware that produces a signal when a physical event or fluctuation is observed.
Device status
The connection state of the physical experiment hardware. On the Quantum Randomness page, it refers specifically to whether the physical QRNG is detected and connected.
Entanglement
A quantum relationship in which the state of a combined system cannot be fully described as independent states of its parts. In Schrödinger’s thought experiment, the nucleus, detector, poison mechanism, and cat become linked to the same outcome.
Event
One recorded detection or signal sample, depending on the experiment.
Expected distribution
The theoretical proportions expected when an experiment is repeated many times. For Natural Radiation, the expected counts-per-minute distribution is a Poisson distribution calculated from the observed mean. For uniformly random bytes, each of the 256 possible values has an expected frequency of 1 / 256, or 0.390625%.
Experiment
A page that explains and exposes one physical measurement path.
Geiger-Müller tube
A gas-filled radiation detector. Ionizing radiation starts an electrical avalanche in the gas, producing a pulse that can be counted.
Half-life
The time over which an unstable nucleus has a 50% probability of decaying. It describes a probability, not the exact lifetime of an individual nucleus. The simulated rubidium-82 nucleus has a half-life of approximately 75 seconds.
Ionization
The removal or addition of an electron, leaving an atom or molecule electrically charged. In the Natural Radiation detector, radiation can eject an electron from a gas atom and initiate the measured pulse.
Live data
Measurements received from the connected physical detector.
Mean
The arithmetic average. In the Quantum Randomness experiment, it is the average of all processed byte values. A perfectly uniform distribution over 0 through 255 has a mean of 127.5.
Natural radiation
Ionizing radiation present in the environment, including radiation from the ground, building materials, air, food, cosmic rays, and other background sources.
Partial
A displayed total for a period with incomplete live-detector coverage. The value is the subtotal actually recorded; missing counts are not estimated.
Photon
A quantum of electromagnetic radiation, including light.
Photon shot noise
Unpredictable fluctuations in the number of photons emitted or detected during a sampling interval. It is the quantum source used by the QRNG described on this site.
Physical randomness
Unpredictability obtained from a measured physical process rather than generated solely by a deterministic software algorithm.
Poisson distribution
A statistical distribution for the number of independent events occurring in equal intervals when the average rate is approximately steady. The Natural Radiation page compares observed complete-minute counts with this distribution.
Pseudorandom
Produced by a deterministic algorithm in a way that appears random. A pseudorandom sequence is reproducible when its algorithm and starting state are known.
Quantum event
An individual physical interaction governed by quantum mechanics, such as ionization caused by radiation or a measurement outcome inside a quantum random number generator.
Quantum random number generator (QRNG)
A device that converts measured quantum fluctuations or outcomes into random data.
Quantum randomness
Randomness produced from quantum measurement outcomes, such as photon detections inside a quantum random number generator.
Radioactive decay
A spontaneous quantum process in which an unstable atomic nucleus changes state and emits radiation. The exact decay time of one nucleus cannot be predicted.
Rubidium-82
A radioactive isotope of rubidium with a half-life of approximately 75 seconds. The Schrödinger’s Cat experiment simulates the decay of one rubidium-82 nucleus; no rubidium-82 is physically present.
Schrödinger’s cat
A thought experiment that links the uncertain decay of a radioactive nucleus to the fate of a cat in a sealed box, illustrating the difficulty of applying quantum superposition to macroscopic objects.
Standard deviation
A measure of spread around an average or expected value. On the Quantum Randomness page, it summarizes how far the 256 observed byte percentages are spread around the expected percentage of 0.390625%.
Superposition
A quantum description in which multiple possible states are represented together until a measurement produces a definite outcome. In Schrödinger’s thought experiment, this leads to the idealized description of the cat as both alive and dead while the box is closed.
Unavailable data
A period or hardware value for which no usable numeric measurement exists. It is distinct from a recorded value of zero.