Glossary
Atomic spectrum
The set of discrete wavelengths emitted or absorbed by an element because electrons can move only between allowed quantum energy levels. The Atomic Spectrum experiment displays neon emission lines.
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.
Calibration
The mapping between detector position and physical wavelength. In the Atomic Spectrum experiment, a fixed two-point neon calibration converts horizontal camera position to wavelength.
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.
Detection sensitivity
The threshold setting used by the Atomic Spectrum line detector. Higher sensitivity admits weaker measured signals but also makes noise-related appearance and disappearance of detected lines more likely.
Detector
Hardware that produces a signal when a physical event or fluctuation is observed.
Device status
The connection state of physical experiment hardware. It reports whether the relevant detector, QRNG, or spectrometer is detected and connected; it is separate from whether an experiment is currently running.
Diffraction grating An optical element with many very closely spaced parallel lines or grooves. These cause different wavelengths of light to leave at different angles, separating the light into its component colors. In the Atomic Spectrum spectrometer, this separation allows different wavelengths to fall at different positions on the camera sensor.
Emission line
Light concentrated around a particular wavelength because an atom emitted a photon during a transition between allowed energy levels.
Energy level
An allowed quantum state of an atom or electron with a particular energy. Electrons in atoms cannot occupy arbitrary energies between these levels.
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.
Excited state
An atomic state with more energy than the ground state. In the neon lamp, collisions can raise electrons into excited states; when they return to lower levels, photons can be emitted.
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 or instrument. On the Atomic Spectrum page, the live data originate from light currently emitted by the continuously operating neon lamp and recorded by the spectrometer camera.
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.
Ne I
Spectroscopic notation for neutral neon atoms. The NIST reference lines on the Atomic Spectrum page are strong Ne I emission lines.
Neon
A noble-gas element with atomic number 10. A neutral neon atom has 10 protons and 10 electrons. Excited neon atoms emit a characteristic set of spectral lines.
NIST The National Institute of Standards and Technology, a U.S. scientific agency that publishes authoritative reference data.
NIST reference line
A neon wavelength taken from the National Institute of Standards and Technology reference table used for comparison on the Atomic Spectrum page. These lines are reference wavelengths, not measured intensities for the lamp used on this site.
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, a measurement outcome inside a quantum random number generator, or the emission of a photon during an atomic transition.
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.
Resolution
The smallest separation an instrument can meaningfully distinguish. The Atomic Spectrum spectrometer has a wavelength resolution of approximately 2–3 nm, so nearby spectral lines may blend and measured peak positions need not exactly match reference wavelengths.
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.
Spectral line
A narrow feature at a particular wavelength in a spectrum. In the Atomic Spectrum experiment, detected spectral lines arise from quantized transitions in neon atoms.
Spectrometer An instrument that separates light by wavelength. In the Atomic Spectrum experiment, light from the neon lamp passes through a narrow slit and is split into its component colors by a diffraction grating inside the spectrometer. Different wavelengths then fall at different positions on the camera sensor, producing the live spectrum used by the experiment.
Spectrum
The distribution of light across wavelength. A continuous spectrum contains a broad range of wavelengths; an atomic emission spectrum contains discrete spectral lines.
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.
Wavelength
The distance between the tops of two consecutive peaks of a wave ∿∿∿∿ For visible light this determines color and is commonly measured in nanometers (nm). In an atomic emission line, the photon wavelength is fixed by the energy difference between the two atomic levels involved in the transition.