Thread by @fgrosshans

Seated for Niraj Kumar PhD defense, on Design, analysis and implementation of advanced quantum communication protocols
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Niraj Kumar introduces the Simultaneous Message PAssing Model (SMP) (i.e. with a referee) to solve the Euclidean distance.
Classical complexity= Ω(√n)
Quantum Complexity=O(log n)
The quantum algorithm uses C-Swap to sample ½(1- |⟨x|y⟩|²

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Niraj Kumar: Controlled SWAP are not realistic in the near term. @ixfoduap and Lutkehaus in 20114 found a way to map it to sequential coherent pulses interaction on a 50:50 beamsplitter and single photon detectors.
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@ixfoduap Niraj Kumar: The gain in quantum transmitted information QTI (O(log n)) is preserved, but the one in quantum transmission time (QTT) disappears.
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@ixfoduap Niraj Kumar has attempted to demonstrate this advantage experimentally in arxiv.org/abs/1811.09154. He was limitted by the noise of InGaAs detectors, but better detectors should be enough to beat classical protocols.
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@ixfoduap Niraj Kumar moves on to sampling matching problems, a varaint of the hidden matching problem where the matching (k,l) is chosen at random.
Alice receives x, Bob outputs a matching, in the matching (k,l) and x_k⊕x_l.
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@ixfoduap Niraj Kumar: The quantum protocol is the same with two |±α⟩ states interfering on a beamsplitter, and the click gives the parity information.He implemented it in arXiv:1811.09154 arxiv.org/abs/1811.09154
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@ixfoduap Sorry, the experimental demonstration of the Euclidean distance is not on in said paper #wrongpaper #LTQI

@ixfoduap Niraj Kumar moves on to private key money schemes, where he propased a scheme based on sampling matching
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Niraj Kumar's comparison with other quantum money schemes #sorryforthebadphoto #LTQI

Niraj Kumar’s PhD last part is on Optimal Measurements. Optimal discrimination for single copy has been well studied. With one-sided error, the optimal measure is a control SWAP, or 50:50 beamsplitter for coherent states #LTQI

Niraj Kumar: look at the case wen we have a single test state, and M–1 reference states. He has a setum with M beamsplitters and log(M) detectors.
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Niraj Kumar's publication list (blue=work related to his thesis)
You can also check his Google scholar page scholar.google.com/citations?user…
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Congratulations to Dr Niraj Kumar!