The results of investigations of Er3+ ions at an optical transition with a telecommunication wavelength (λ~1530 nm) in a YPO4 crystal by using photon echo and high-resolution laser spectroscopy in magnetic fields up to 4 T are presented. The maximum coherence time (T2) was 113 μs in a magnetic field of 4 T when it is oriented along the optical axis c of the crystal. The main sources of decoherence are discussed.

quantum memory protocol has been implemented on the basis of the revival of silenced echo (ROSE) in the 167 Er 3+ :Y 2 SiO 5 crystal at the telecommunication wavelength for input light fields with a small number of photons. An efficiency of storage of 44% has been reached at a storage time of 40 μs. The input pulse contains ~340 photons on average, the reconstructed echo signal includes ~150 photons, and the signal-to-noise ratio is 4. It has been shown that the main source of noise is the spontaneous emission of atoms remaining in the excited state because the parameters of two rephasing pulses are imperfect. Methods of increasing the signal-to-noise ratio for the implementation of the efficient quantum memory for single-photon fields have been discussed.

A quantum memory protocol has been implemented on the basis of the revival of silenced echo (ROSE) in the 167Er3+:Y2SiO5 crystal at the telecommunication wavelength for input light fields with a small number of photons. An efficiency of storage of 44% has been reached at a storage time of 40 μs. The input pulse contains ~340 photons on average, the reconstructed echo signal includes ~150 photons, and the signal-to-noise ratio is 4. It has been shown that the main source of noise is the spontaneous emission of atoms remaining in the excited state because the parameters of two rephasing pulses are imperfect. Methods of increasing the signal-to-noise ratio for the implementation of the efficient quantum memory for single-photon fields have been discussed.

Впервые применен метод томографии квантовых процессов на основе критериев адекватности полноты и точности к характеризации однокубитной оптической квантовой памяти в протоколе фотонного эха на атомной частотной гребенке. Построена адекватная модель квантового процесса, учитывающая основные физические неидеальности. В результате полученная матрица квантового процесса с точностью до 96 % совпала с идеальным единичным преобразованием.