Check out our new preprint on the "Two-Photon Bandwidth of Hyper-Entangled Photons in Complex Media"! @RonenShekel @OhadLib @WFShaping @BrombergYaron
We show that the bandwidth of hyper-entangled photons is much larger than their classical counterpart. A thread 🧵.
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1/ Link: arxiv.org/abs/2512.09456
When coherent light propagates through a multimode fiber, the output speckle pattern is highly sensitive to wavelength. This "spectral correlation width" fundamentally limits the bandwidth for imaging and communication.
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2/We ask: What happens with hyper-entangled photons – pairs entangled in both space and frequency? We demonstrate a novel "modal dispersion cancellation" effect: the chromatic dispersion experienced by one photon is canceled to first order by its spectrally anti-correlated twin.
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4/ We show that while the geometric effect due to diffraction remains, the phase-wrapping effect is cancelled with hyper-entangled photons, resulting with a high contrast speckle on the optical axis.
Dec 11, 2025 · 12:12 PM UTC
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5/ We also look at blazed gratings – a cornerstone example of spatio-temporal effects. Also here there are two effects: a) The rainbow that appears at each diffraction order – a geometric effect due to diffraction. b) Leakage to other diffraction orders due to phase wrapping.
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6/ Once again, with hyper-entangled photons the phase-wrapping effect is cancelled, and all coincidence events occur at the m=2 diffraction order.
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7/Why does this matter? Control. A high-contrast pattern is the key prerequisite for wavefront shaping. We demonstrate numerically that this cancellation allows for broadband wavefront shaping of quantum states, overcoming the severe classical spectral limitations.
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8/ Interestingly, if the SLM is placed before the multimode fiber – the cancellation effect is ruined. To perform wavefront shaping we must place the SLM after the multimode fiber!
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9/ This brings us all the way back to our previous work on Fundamental bounds of wavefront shaping of spatially entangled photons: pubs.aip.org/aip/app/article…
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10/ Read the paper for full details: arxiv.org/abs/2512.09456
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