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The quantum dots that emit on demand the pairs of entangled photons could be used in quantum communication networks
D. Huber and C. Schimpf / Johannes Kepler University
Communication protocols and quantum computing require sources of photons whose quantum states are strongly correlated or "entangled". Sources of photon pairs with exceptional degrees of entanglement do not exist. on demand. Now Daniel Huber of the Johannes Kepler University, Austria, and his colleagues have demonstrated a source of demand-interleaved photon pairs based on nanostructures of semiconductor materials known as quantum dots.
Advanced entangled photon sources on a process called parametric downconversion, which converts an input photon into a pair of entangled photons. Such sources, however, emit entangled photons at random times. In contrast, quantum dots can produce entangled photon pairs on demand. But usually the pairs that they produce are not perfectly entangled because of the decoherence of the quantum states of the point. A particularly detrimental decoherence mechanism is due to an effect known as fine-structure splitting, which spoils the entanglement by muddling the relative phase of the two photons emitted
Huber and others solved this problem with a piezoelectric device that, by applying a stress to a GaAs quantum dot, modifies the symmetry of the potential that confines the electrons and holes in the point, thus erasing the division of the fine structure. In experiments, the team found a level of entanglement between photons emitted 10% higher than the best sources of previously reported quantum dots and almost equal to that of parametric conversion sources. These new sources, which are enclosed in thin micrometric membranes, could easily be incorporated into integrated photonic circuits.
This research is published in Physical Review Letters .
-Mallory Pickett
Mallory Pickett is a freelance writer based in California
Quantum GaAs Strain-Adjustable Point: A source of Pairs Photons Entangled Almost Dephasing on Demand
Daniel Huber, Marcus Reindl, Saimon Filipe Covre da Silva, Christian Schimpf, Javier Martín-Sánchez, Huiying Huang, Giovanni Piredda, Johannes Edlinger, Armando Rastelli and Rinaldo Trotta
Phys. Rev. Lett. 121 033902 (2018)
Published July 18, 2018
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