Advances in optical quantum networks, which transmit information by encoding data via the quantum state of photons, have been leading to breakthroughs in quantum photonics such as the recent demonstration of quantum communication in real-world conditions. However, because qubits are delicate, despite their ability to store vast amounts of information, a massive amount of effort is now being poured into the development of reliable, practical quantum memory schemes that might eventually be able to be scaled down to chip-sized quantum devices.
Recently, researchers at Caltech took some significant steps in this direction. The team created an optical quantum memory device over 1,000 times smaller than anything developed before. This device is even able to fit into on-chip devices and, according to their published results, it is also capable of on-demand retrieval of stored data.
The research team developed a nano-sized cavity containing light-trapping, rare-earth (or lanthanide), neodymium atoms which are trapped in a yttrium orthovanadate (YVO) crystal. The cavity, in turn, creates a crystal cavity which enhances interactions between neodymium and light at the level of single photons. This technology may take us closer to the quantum internet because it makes both on-demand retrieval and high-fidelity memory a reality.
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