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Cesium Clock
The ability to make precision measurements in a short amount of time has jumped enormously.
Evaporative Cooling
When Zwierlein applies a certain radio frequency to the trapped atoms, it shaves off the hotter atoms and leaves the cooler ones.
Frequency of Cesium Atoms
Cesium atoms run at a frequency of around 10 billion cycles per second, which corresponds to a microwave frequency.
Laser Cooling 1
The key to laser cooling is that in the process of absorbing a photon, an atom receives a small push in the direction away from the source of light.
Laser Cooling 2
As atoms continuously absorb photons coming from one direction, and re-emit photons in random directions, the net result is a loss of momentum.
Laser Cooling 3
The cooling inside the chamber takes place in several steps. The ultimate temperature they can reach is limited and they will need to be cooled further.
Mercury Trap
Removing the electron gives the ion an electrical charge, so it can be suspended in a trap by electric forces.
Photon as Electromagnetic Wave
A photon, a particle of light, can be thought of as an electromagnetic wave with a particular oscillation frequency.
Photon Frequency and Excitement of Atoms
The probability that the atoms will be excited out of their ground state reaches a peak when the photons are tuned to exactly the right frequency.


nobel prize winners 1997
1997 Nobel Prize Winners
Recipients of the 1997 Nobel Prize, for laser cooling and trapping of atoms.
Atoms in a MOT
Atoms trapped in a magneto-optical trap.
Neutral rubidium atoms in an optical lattice trap.
Atoms in an Optical Lattice
Neutral rubidium atoms in an optical lattice trap.
uncertainty apparatus
g-2 Experiment
Gerald Gabrielse (left) is shown with the apparatus he used to make some of the most precise measurements of a single electron.
photos of bust of Heisenberg and Scrodinger
Heisenberg and Schrödinger
Left: Werner Heisenberg; right: Erwin Schrödinger.
This furnace for melting glass behaves almost like a blackbody radiation source.
Industrial Furnace
This furnace for melting glass is nearly an ideal blackbody radiation source.
Laser of light
Next-Generation Clock
The heart of a next-generation optical clock.
Max Planck portrait
Planck, Max
Max Planck solved the blackbody problem by introducing quanta of energy.
Rabi, Isidor Isaac
Isidor Isaac Rabi pioneered atomic physics in the U.S. during the 1930s, invented magnetic resonance, and first suggested the possibility of an atomic clock.
ripples on a pond
Ripples on a Pond
A circular wave created by tossing a pebble in a pond.
single slit and two slit interference
Single and Two-Slit Interference
Diffraction of laser light through one (top) and two (bottom) small slits.
Trapped Ions
Thirty-two ions, fluorescing under illumination by laser light in an electrodynamic trap.
baseball with pitcher
Uncertainty in a Baseball
The effect of quantum mechanical jitter on a pitcher, fortunately, is too small to be observable.

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Atomic Fountain
Schematic diagram of an atomic fountain clock.
Black Hole Jet
This VLBI image of jets from a black hole could not have been produced without atomic clocks.
Model of the atom by Niels Bohr
Bohr's Model of the Atom
Model of the atom by Niels Bohr.
cosmic microwave background spectrum
Cosmic Microwave Background Spectrum
Spectrum of the cosmic microwave background radiation.
Diffraction of Atoms
This diffraction pattern appeared when a beam of sodium molecules encountered a series of small slits, showing their wave-like nature.
Doppler Cooling
Red-detuned lasers don't affect an atom at rest (left) but will slow an atom moving towards the light source (right).
Electromagnetic Spectrum from radio waves to gamma rays.
Electromagnetic Spectrum
The electromagnetic spectrum from radio waves to gamma rays.
Electron interference pattern
Electron Interference
An interference pattern builds up as individual electrons pass through two slits.
simple harmonic oscillator and energy diagram
Harmonic Oscillator
A simple harmonic oscillator (bottom) and its energy diagram (top).
harmonic oscillator energy levels
Harmonic Oscillator Energy Levels
Low-lying energy levels of a harmonic oscillator.
harmonic oscillator, n-40
Harmonic Oscillator, n=40
The wavefunction (left) and probability distribution (right) of a harmonic oscillator in the state n = 40.
Hydrogen Atom
The size of a hydrogen atom is determined by the uncertainty principle.
spectrum of atomic hydrogen
Hydrogen Spectrum
The spectrum of atomic hydrogen.
atomic fountain
NIST F1 Clock
This apparatus houses the NIST F1 cesium fountain clock, which is the primary time and frequency standard of the United States.
Optical Lattice
Atoms trapped in an optical lattice.
wave graphic
Particle in a Box
The first three allowed de Broglie wave modes for a particle in a box.
plane waves
Single-Slit Interference
Ripple tank picture of plane waves incident on a slit that is about two wavelengths wide.
standing wave graphic of three excited states
Standing Waves
Standing waves on a string between two fixed endpoints.
temperature scales in physics
Temperature Scale
Temperature scale in physics.
two circular waves crossing paths.
Two-Wave Interference
Two waves interfere as they cross paths.
Waves emerging from slits
Various Interference Effects
The two-slit interference pattern depends on the distance between the slits.
ground state harmonic oscillator
Wavefunction and Probability Distribution
The ground state wavefunction of a harmonic oscillator (left) and the corresponding probability distribution (right).
wavefunctions for a particle in a box
(a)-(d) Some wavefunctions for a particle in a box. Curve (e) is the sum of curves (a-d).