Atom Interferometer Simulator

Atom Interferometer

Applied acceleration a 0.0 m/s²

Rotation rate Ω 0.0 rad/s

Pulse separation T 120 ms

Cloud size 700 atoms

Phase shift Δφ

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Fringe (cos Δφ)

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Port A pop.

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Port B pop.

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Fringe readout — P(port A) vs phase, last shots in orange

How it works

A cloud of laser-cooled atoms is hit by three light pulses spaced by time T. The first (π/2) puts each atom into a superposition of "stayed" and "absorbed a photon momentum kick", splitting its matter wave into two paths. The second (π) at time T swaps momentum states, bending the paths back toward each other. The third (π/2) at time 2T recombines them, and which output port an atom is detected in depends on the phase difference the two paths picked up along the way.

Δφ = k_eff·a·T² + κ·Ω·T²   (scaled units for visualization)
P(A) = (1 + cos Δφ)/2
P(B) = 1 − P(A)

Applied acceleration — shifts the phase quadratically with T; this is exactly the signal a cold-atom gravimeter reads to measure local gravity.
Rotation rate — the Sagnac-type term from the enclosed space-time area between the two paths; the basis of atom-interferometric gyroscopes.
Pulse separation T — longer free-fall time between pulses means more phase accumulates per unit of acceleration or rotation, but also more chance for the cloud to disperse.
The diamond-shaped path in the beam tube is the classic space-time diagram of a Mach-Zehnder atom interferometer, drawn here in real space instead of space-time.

Real-world relevance: this exact pulse sequence runs today in transportable atom gravimeters used for geodesy and resource surveying, and in atom-interferometric gyroscopes proposed for drift-free inertial navigation.

Path A — ground state Path B — recoil state Laser pulse plane

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