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Register a new userSpectral hole lifetimes and spin population relaxation dynamics in neodymium-doped yttrium orthosilicate
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Emmanuel Zambrini Cruzeiro
Publication date
2016
fields
Physics
and research's language is
English
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We present a detailed study of the lifetime of optical spectral holes due to population storage in Zeeman sublevels of Nd$^{3+}$:Y$_2$SiO$_5$. The lifetime is measured as a function of magnetic field strength and orientation, temperature and Nd$^{3+}$ doping concentration. At the lowest temperature of 3 K we find a general trend where the lifetime is short at low field strengths, then increases to a maximum lifetime at a few hundreds of mT, and then finally decays rapidly for high field strengths. This behaviour can be modelled with a relaxation rate dominated by Nd$^{3+}$-Nd$^{3+}$ cross relaxation at low fields and spin lattice relaxation at high magnetic fields. The maximum lifetime depends strongly on both the field strength and orientation, due to the competition between these processes and their different angular dependencies. The cross relaxation limits the maximum lifetime for concentrations as low as 30 ppm of Nd$^{3+}$ ions. By decreasing the concentration to less than 1 ppm we could completely eliminate the cross relaxation, reaching a lifetime of 3.8 s at 3~K. At higher temperatures the spectral hole lifetime is limited by the magnetic-field independent Raman and Orbach processes. In addition we show that the cross relaxation rate can be strongly reduced by creating spectrally large holes of the order of the optical inhomogeneous broadening. Our results are important for the development and design of new rare-earth-ion doped crystals for quantum information processing and narrow-band spectral filtering for biological tissue imaging.
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We investigate the electron and nuclear spin coherence properties of ytterbium ($mathrm{Yb}^{3+}$) ions with non-zero nuclear spin, within an yttrium orthosilicate (Y$_2$SiO$_5$) crystal, with a view to their potential application in quantum memories or repeaters. We find electron spin-lattice relaxation times are maximised at low magnetic field ($<100$ mT) where $g~sim6$, reaching 5 s at 2.5 K, while coherence times are maximised when addressing ESR transitions at higher fields where $gsim0.7$ where a Hahn echo measurement yields $T_2$ up to 73 $mu$s. Dynamical decoupling (XY16) can be used to suppress spectral diffusion and extend the coherence lifetime to over 0.5 ms, close to the limit of instantaneous diffusion. Using Davies electron-nuclear-double-resonance (ENDOR), we performed coherent control of the $^{173}mathrm{Yb}^{3+}$ nuclear spin and studied its relaxation dynamics. At around 4.5 K we measure a nuclear spin $T_1$ and $T_2$ of 4 and 0.35 ms, respectively, about 4 and 14 times longer than the corresponding times for the electron spin.
Doping of substrates at desired locations is a key technology for spin-based quantum memory devices. Focused ion beam implantation is well-suited for this task due to its high spacial resolution. In this work, we investigate ion-beam implanted erbium ensembles in Yttrium Orthosilicate crystals by means of confocal photoluminescence spectroscopy. The sample temperature and the post-implantation annealing step strongly reverberate in the properties of the implanted ions. We find that hot implantation leads to a higher activation rate of the ions. At high enough fluences, the relation between the fluence and final concentration of ions becomes non-linear. Two models are developed explaining the observed behaviour.
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