Rare earth metals will help physicists to build larger quantum networks

American physicists have implemented a highly coherent control and readout of single ytterbium ions placed in an optical resonator. This experiment opens the way to the creation of large-scale quantum networks based on ions. The work presented in the journal Nature.

Distribution of quantum entanglement over large distances in optical quantum networks is one of the key protocols of quantum cryptography and distributed quantum computing. Solid-state sources of confusion associated with optical cavities are promising candidates for realization of scalable quantum networks. In particular, physicists have investigated systems such as quantum dots and defects in diamond or silicon carbide.

However, until now, the scaling of solid-state systems remains in question, the Central problem is to find systems with controlled coherent optical and spin transitions. Not so long ago it was discovered that rare earth metals in the crystal have enough coherence and, theoretically, may be associated with the optical resonator.

A group of American physicists under the direction of Professor Andrei Faraon (Andrei Faraon) used ions of ytterbium, made in crystal, to demonstrate the high coherence of spin States and fast-read state in the optical resonator.

As kubango state on the basis of which it was built, the confusion, the researchers used a coherent state of the electron with the core ion. The excitation of the qubit with help of microwave radiation, and the measurements were performed using an additional pulse is applied to the excited state of the qubit, which led to fluorescence of the iononly if the qubit was in the excited state. The measurements were carried out with a superconducting detector of the photons in the dissolution cryostat at the temperature of 40 millikelvin.

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