AQA ยท A level Physics

Atom interferometer noise cancellation challenge

Can you get 100%? Use two atom interferometers to test phase, interference, common-mode noise cancellation and measurement sensitivity.

Read how the atom sensor cancels laser noise

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Question

8 marks

Answer all parts. Show your working and give units where appropriate.

1(a)

Two coherent matter-wave paths recombine with phase difference pi radians. State the type of interference expected and explain your answer.

[2 marks]

1(b)

During one measurement the phase readouts are 0.93 rad and 0.77 rad. Shared laser noise has added the same unknown phase to both readouts. Calculate the differential phase and explain why the shared noise cancels.

[3 marks]

1(c)

A future detector would search for a tiny signal that changes the relative phase of separated atom interferometers. Describe three checks needed to show that a measured differential phase is not an instrumental effect.

[3 marks]

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