| 1. |
- Alqedra, Mohammed K., et al.
(author)
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Optical coherence properties of Kramers' rare-earth ions at the nanoscale for quantum applications
- 2023
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In: Physical Review B. - 2469-9950. ; 108:7
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Journal article (peer-reviewed)abstract
- Rare Earth (RE) ion doped nanomaterials are promising candidates for a range of quantum technology applications. Among RE ions, the so-called Kramers' ions possess spin transitions in the GHz range at low magnetic fields, which allows for high-bandwidth multimode quantum storage, fast qubit operations as well as interfacing with superconducting circuits. They also present relevant optical transitions in the infrared. In particular, Er3+ has an optical transition in the telecom band, while Nd3+ presents a high-emission-rate transition close to 890 nm. In this paper, we measure spectroscopic properties that are of relevance to using these materials in quantum technology applications. We find the inhomogeneous linewidth to be 10.7 GHz for Er3+ and 8.2 GHz for Nd3+, and the excited state lifetime T1 to be 13.68 ms for Er3+ and 540μs for Nd3+. We study the dependence of homogeneous linewidth on temperature for both samples, with the narrowest linewidth being 379 kHz (T2=839 ns) for Er3+ measured at 3 K, and 62 kHz (T2=5.14μs) for Nd3+ measured at 1.6 K. Further, we investigate time-dependent homogeneous linewidth broadening due to spectral diffusion and the dependence of the homogeneous linewidth on magnetic field to get additional clarity of mechanisms that can influence the coherence time. In light of our results, we discuss two applications: single qubit-state readout and a Fourier-limited single photon source.
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| 2. |
- Bartholomew, John G., et al.
(author)
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High-resolution spectroscopic techniques for studying rare-earth ions in nanoparticles
- 2023
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In: Journal of Luminescence. - : Elsevier BV. - 0022-2313. ; 257
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Journal article (peer-reviewed)abstract
- Rare-earth doped nanoparticles can exhibit narrow optical and spin linewidths at low temperatures. These outstanding properties for nanomaterials make them attractive for quantum technologies based on optically addressable spins such as quantum memories and computers. Although accurate linewidth measurements have been reported using, for example, spectral hole burning or photon echo techniques, so far they have been mostly restricted to large ensembles of particles. Being able to extend linewidths measurements to few and single particles is particularly important in view of their integration in nanophotonic devices. In this paper, we present techniques for determining inhomogeneous and homogeneous linewidths of small ensembles of rare-earth ions in doped nanoparticles with high signal-to-noise ratios for convenient integration times. Using these techniques we have observed property variations for particles from the same synthesis, a first step towards their optimization for applications in quantum technologies.
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| 3. |
- Becher, Christoph, et al.
(author)
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2023 roadmap for materials for quantum technologies
- 2023
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In: Materials for Quantum Technology. - : IOP Publishing. - 2633-4356. ; 3:1
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Journal article (peer-reviewed)abstract
- Quantum technologies are poised to move the foundational principles of quantum physics to the forefront of applications. This roadmap identifies some of the key challenges and provides insights on material innovations underlying a range of exciting quantum technology frontiers. Over the past decades, hardware platforms enabling different quantum technologies have reached varying levels of maturity. This has allowed for first proof-of-principle demonstrations of quantum supremacy, for example quantum computers surpassing their classical counterparts, quantum communication with reliable security guaranteed by laws of quantum mechanics, and quantum sensors uniting the advantages of high sensitivity, high spatial resolution, and small footprints. In all cases, however, advancing these technologies to the next level of applications in relevant environments requires further development and innovations in the underlying materials. From a wealth of hardware platforms, we select representative and promising material systems in currently investigated quantum technologies. These include both the inherent quantum bit systems and materials playing supportive or enabling roles, and cover trapped ions, neutral atom arrays, rare earth ion systems, donors in silicon, color centers and defects in wide-band gap materials, two-dimensional materials and superconducting materials for single-photon detectors. Advancing these materials frontiers will require innovations from a diverse community of scientific expertise, and hence this roadmap will be of interest to a broad spectrum of disciplines.
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| 4. |
- Karlsson, Jenny, et al.
(author)
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High-resolution transient and permanent spectral hole burning in Ce3+ : Y2SiO5 at liquid helium temperatures
- 2016
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In: Physical Review B. - 1098-0121. ; 93:22
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Journal article (peer-reviewed)abstract
- We perform hole burning with a low-drift stabilized laser within the zero phonon line of the 4f-5d transition in Ce3+:Y2SiO5 at 2 K. The narrowest spectral holes appear for small applied magnetic fields and are 6±4 MHz wide (FWHM). This puts an upper bound on the homogeneous linewidth of the transition to 3±2 MHz, which is close to lifetime limited. The spin level relaxation time is measured to 72±21 ms with a magnetic field of 10 mT. A slow permanent hole burning mechanism is observed. If the excitation frequency is not changed the fluorescence intensity is reduced by more than 50% after a couple of minutes of continuous excitation. The spectral hole created by the permanent hole burning has a width in the tens of MHz range, which indicates that a trapping mechanism occurs via the 5d state.
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| 5. |
- Lovric, Marko, et al.
(author)
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Hyperfine characterization and spin coherence lifetime extension in Pr3+:La-2(WO4)(3)
- 2011
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 84:10
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Journal article (peer-reviewed)abstract
- Rare-earth ions in dielectric crystals are interesting candidates for storing quantum states of photons. A limiting factor on the optical density and thus the conversion efficiency is the distortion introduced in the crystal by doping elements of one type into a crystal matrix of another type. Here we investigate the system Pr3+:La-2(WO4)(3), where the similarity of the ionic radii of Pr and La minimizes distortions due to doping. We characterize the praseodymium hyperfine interaction of the ground-state (H-3(4)) and one excited state (D-1(2)) and determine the spin Hamiltonian parameters by numerical analysis of Raman-heterodyne spectra, which were collected for a range of static external magnetic-field strengths and orientations. On the basis of a crystal-field analysis, we discuss the physical origin of the experimentally determined quadrupole and Zeeman tensor characteristics. We show the potential for quantum memory applications by measuring the spin coherence lifetime in a magnetic field that is chosen such that additional magnetic fields do not shift the transition frequency in first order. Experimental results demonstrate a spin coherence lifetime of 158 ms - almost 3 orders of magnitude longer than in zero field.
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| 6. |
- Yan, Ying, et al.
(author)
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Measurement of linewidths and permanent electric dipole moment change of the Ce 4f-5d transition in Y2SiO5 for qubit readout scheme in rare-earth ion based quantum computing
- 2013
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 87:18
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Journal article (peer-reviewed)abstract
- In this work the inhomogeneous (zero-phonon line) and homogeneous linewidths and the permanent electric dipole moment change (averaged value of all dipole orientations) for the Ce 4f-5d transition in Y2SiO5 were measured in order to investigate the possibility for using Ce as a sensor to detect the hyperfine state of a spatially close-lying Pr or Eu ion. The experiments were carried out on Ce doped or Ce-Pr co-doped single Y2SiO5 crystals. The homogeneous linewidth is essentially limited by the excited state lifetime. Based on the linewidth measurements, the oscillator strength, absorption cross section, and saturation intensity were calculated to be about 6.2(+/- 1.7) x 10(-7), 4.5(+/- 1.3) x 10(-19) m(2), and 1.4(+/- 0.4) x 10(7) W/m(2), respectively. The difference in permanent dipole moment, Delta mu(Ce), between the ground and excited states of the Ce ion was measured as 9.6(+/- 5.3) x 10(-30) C m. These measurements indicate that Ce is a promising readout ion to probe a single-ion qubit state for the quantum computing scheme using rare-earth ions.
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