Computational advantage from quantum superposition of multiple temporal orders of photonic gates
| Autor: | Taddei, Márcio M., Cariñe, Jaime, Martínez, Daniel, García, Tania, Guerrero, Nayda, Abbott, Alastair A., Araújo, Mateus, Branciard, Cyril, Gómez, Esteban S., Walborn, Stephen P., Aolita, Leandro, Lima, Gustavo |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | PRX Quantum 2, 010320 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PRXQuantum.2.010320 |
| Popis: | Models for quantum computation with circuit connections subject to the quantum superposition principle have been recently proposed. There, a control quantum system can coherently determine the order in which a target quantum system undergoes $N$ gate operations. This process, known as the quantum $N$-switch, is a resource for several information-processing tasks. In particular, it provides a computational advantage -- over fixed-gate-order quantum circuits -- for phase-estimation problems involving $N$ unknown unitary gates. However, the corresponding algorithm requires an experimentally unfeasible target-system dimension (super)exponential in $N$. Here, we introduce a promise problem for which the quantum $N$-switch gives an equivalent computational speed-up with target-system dimension as small as 2 regardless of $N$. We use state-of-the-art multi-core optical-fiber technology to experimentally demonstrate the quantum $N$-switch with $N=4$ gates acting on a photonic-polarization qubit. This is the first observation of a quantum superposition of more than $N=2$ temporal orders, demonstrating its usefulness for efficient phase-estimation. Comment: Main text: 9 pages, 3 figures; total 15 pages, 5 figures |
| Databáze: | arXiv |
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