AQA ยท A level Physics

Quantum light chip and coherence challenge

Can you get 100%? Use a room-temperature patterned optical chip to test photon energy, coherence, interference and careful scientific claims.

Read how the chip controls quantum light

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Question

8 marks

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

1(a)

The chip is tested with light of wavelength 1550 nm. Calculate the photon energy. Use h = 6.63 x 10^-34 J s and c = 3.00 x 10^8 m s^-1.

[3 marks]

1(b)

Two optical paths recombine on the chip. Explain why stable interference requires coherence between the paths.

[2 marks]

1(c)

Researchers prepare several input light beams with known photon-count statistics. They measure the statistics after the light passes through the patterned chip and compare the results with an unpatterned control chip. Explain two comparisons needed to show that the patterned chip selectively changes photon statistics, and explain why this result does not mean that the researchers have built a room-temperature quantum computer.

[3 marks]

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