PHYSICS / FREQUENCY STANDARDS

Caesium fountain
atomic clock.

Explore the architecture behind the definition of a second.

01 / COMPLETE ASSEMBLYDRAG TO ROTATE · SCROLL TO ZOOM

LIVE INSTRUMENTATIONILLUSTRATIVE PHYSICS

APOGEE HEIGHT—m · ballistic

RAMSEY INTERVAL—s · between crossings

FRINGE WIDTH—Hz · idealised

QUALITY FACTOR—× 10⁹ · model

EXHIBIT CONTROL SYSTEM

Laboratory / 01

ACTIVE

Inspection mode

Assembly inspection

Subsystem SELECT TO INSPECT Explosion distance 0% Enclosure cutaway 0%

Educational callouts

Animate process

Experimental model

Launch velocity 4.3 m/s Microwave detuning +0.35 Hz

REFERENCE TRANSITION / TEXTBOOK9 192 631 770 Hz

IDEALISED STATE RESPONSE —

INDEPENDENT CHECK—Numerical trajectory vs. h = v² / (2g)

Assembly sequence

DEPENDENCY-ORDERED BUILD

Ready for guided assembly

Build the exhibit in a nine-stage dependency order.

Display & camera

Lighting rig Geometry detail

Structural chassis

Outer shielding

The science Equations & limitations

Real mechanism. Laser-cooled caesium-133 atoms are launched through the same microwave cavity on ascent and descent. The state populations detected after the flight support a frequency feedback loop.

Textbook constants. Gravitational acceleration g = 9.80665 m/s² (standard acceleration) and the SI defining caesium-133 hyperfine transition ν₀ = 9,192,631,770 Hz.

Illustrative equations. Ballistic height h = v₀²/(2g). Microwave-cavity crossing interval T = 2√(v₀² − 2gd)/g for a crossing plane d = 0.24 m above launch. Idealised Ramsey central-fringe width Δν ≈ 1/(2T). Derived frequency ratio Q = ν₀/Δν. Illustrative transition envelope P = cos²(πΔfT).

What is simplified. No velocity spread, finite microwave pulse duration, state-preparation imperfections, noise, atomic collisions, magnetic perturbations, or uncertainty budget. The displayed probability is not a validated quantum-processor prediction or real clock performance.

Visual classification. Two-pass microwave interrogation, six-axis cooling access and state-sensitive readout are genuine concepts. Frame spacing, pump routing, optical rack layout and materials are engineering-inspired. Glow, beams, atom packets and disassembly motion are scaled educational illustrations.

Illustrative design, not affiliated with any real institution or manufacturer.

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Caesium fountainatomic clock.

Caesium fountain
atomic clock.