Rare-earth-doped laser materials show strong prospects for quantum information storage and processing, as well as for biological imaging, due to their high-Q 4f↔4f optical transitions. However, the inability to optically detect single rare-earth dopants has prevented these materials from reaching their full potential. Here we detect a single photostable Pr3+ ion in yttrium aluminium garnet nanocrystals with high contrast photon antibunching by using optical upconversion of the excited state population of the 4f↔4f optical transition into ultraviolet fluorescence. We also demonstrate on-demand creation of Pr3+ ions in a bulk yttrium aluminium garnet crystal by patterned ion implantation. Finally, we show generation of local nanophotonic structures and cell death due to photochemical effects caused by upconverted ultraviolet fluorescence of praseodymium-doped yttrium aluminium garnet in the surrounding environment. Our study demonstrates versatile use of rare-earth atomic-size ultraviolet emitters for nanoengineering and biotechnological applications. The optical transitions that occur in rare-earth-doped crystals offer promise for quantum information storage and processing. Kolesovet al.report the optical detection of a single praseodymium ion residing in a crystal host by using an excited-state absorption process to enhance its fluorescence yield.
Rare-Earth Quantum Device Project aims to develop quantum devices based on gallium nitride (GaN), which has high quality and advanced microfabrication and device technologies, and rare-earth ions (RE3+), which have excellent characteristics as qubits and single photon sources. RE:GaN quantum devices have the potential to realize "electrically controlled single photon sources (SPSs) in the optical communication wavelength band at room temperature," "on-chip quantum entangled light sources," and "real-time diagnostics inside GaN devices by quantum sensing," which have not been achieved to date. Currently, our project studies ion implantation and post thermal annealing for high efficiency optical activation of implanted RE ions in GaN, local atomic structure of implanted RE ions, development of quantum sensing using RE ions in GaN, and enhancement of spontaneous emission of implanted RE ions in GaN by coupling to photonic crystal.
The thesis is primarily concerned with rare earth ions doped into yttrium ortho silicate crystals, RE:YSO. It is considered to be an ambitious platform for the development of quantum computing schemes. One such scheme requires the detection of single cerium ions. The project was aimed at measuring the saturation intensity of cerium 5d-4f transition which is needed for the single ion detection. This work contains theoretical simulations as well as measurements of fluorescence from rare earth ions sitting inside of a crystal as a function of excitation power. For practical reasons the measurement could not be carried out on cerium, but praseodymium was used instead. By measuring the saturation intensity one can derive the homogeneous linewidth that contributes to the detection procedure. The major complication in this type of measurement is the power broadening. Therefore, the measurement was aided by a theoretical simulation. The data was then fit with simulated theoretical results. The measurement was inconclusive for several reasons that are discussed at the end. However, this work is a priceless reference for the future cerium saturation intensity measurement or another experiment that needs to consider power broadening effects.
Rare-earth ion ensembles doped in single crystals are a promising materials system with widespread applications in optical signal processing, lasing, and quantum information processing. Incorporating rare-earth ions into integrated photonic devices could enable compact lasers and modulators, as well as on-chip optical quantum memories for classical and quantum optical applications. To this end, a thin film single crystalline wafer structure that is compatible with planar fabrication of integrated photonic devices would be highly desirable. However, incorporating rare-earth ions into a thin film form-factor while preserving their optical properties has proven challenging. We demonstrate an integrated photonic platform for rare-earth ions doped in a single crystalline thin film lithium niobate on insulator. The thin film is composed of lithium niobate doped with Tm 3+ . The ions in the thin film exhibit optical lifetimes identical to those measured in bulk crystals. We show narrow spectral holes in a thin film waveguide that require up to 2 orders of magnitude lower power to generate than previously reported bulk waveguides. Our results pave the way for scalable on-chip lasers, optical signal processing devices, and integrated optical quantum memories.
Without using any trapping lasers, rare-earth (RE) ions can be doped into some nanofabricated materials in form of nanocrystals in a solid state matrix, thus rendering a natural trap for potential application as a quantum computing device. In particular, passive nuclear spin states of RE ions can be utilized as (i) optical quantum memory (with huge density as yielded from nanocrystals), (ii) qubits by encoding in ground hyperfine states and operated as (iii) two-qubit gate when transferring them to active magnetized electronic states. A feasible implementation of qubits is realised by using those doped RE ions whose open-shell (for inner highly shielded
4f shell electrons) energy levels and statevectors are well described by the crystal field (CF) interaction and hyperfine coupling in which the Hamiltonian is composed of various freeion interactions, the CF potential, electronic and nuclear Zeeman effects as well as the hyperfine interaction. For those qubit encoded in the two ground hyperfine states of RE ions, they can have fairly long lifetimes of days and coherence times (from 1.3s for
Er3+ to 6 hours for
Eu3+) due to the unique spectroscopic properties of RE ions. Because of the recent progress in optical single-ion detection for addressing individual qubits with a specific frequency channel, RE ions could be packed in a solid state 3D matrix at nanometer spacing, hence rendering very high qubit densities for quantum memories. Meanwhile, this configure also leads to strong dipole-dipole interactions (or high connectivity) between qubits which are not nearest neighbors. In this study, Kramers ions like
167Er and
171Yb doped in yttrium orthosilicate
Y2SiO5 (YSO) nanocrystals will be investigated as a promising system for quantum computing because of their weak spin bath and possibility for being directly milled in single nanocrystals as nano-resonators. By using the famous Wien2k package to carry out the first-principles calculations, we can obtain the CF parameters and hyperfine constants as well as various electronic properties like energy gap and band structure for those Kramers RE ions doped in YSO. We shall present some essential findings from first-principles calculations to obtain various properties of the ground and excited CF and hyperfine states for those RE ions with an aim to optimize RE ions doping in YSO nanocrystals for quantum memories and qubits, contributing to scalable quantum computing architectures.