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Author(s): H. Häffner (corresponding author) [1, 3]; W. Hänsel [1]; C. F. Roos [1, 3]; J. Benhelm [1, 3]; D. Chek-al-kar [1]; M. Chwalla [1]; T. Körber [1, 3]; U. [...]

Author(s): M. Riebe [1]; H. Häffner [1]; C. F. Roos [1]; W. Hänsel [1]; J. Benhelm [1]; G. P. T. Lancaster [1]; T. W. Körber [1]; C. Becher [1]; F. [...]

We report fluorescence investigations and Raman spectroscopy on colloidal nanodiamonds (NDs) obtained via bead assisted sonic disintegration (BASD) of a polycrystalline chemical vapor deposition film. The BASD NDs contain in situ created silicon vacancy (SiV) centers. Whereas many NDs exhibit emission from SiV ensembles, we also identify NDs featuring predominant emission from a single bright SiV center. We demonstrate oxidation of the NDs in air as a tool to optimize the crystalline quality of the NDs via removing damaged regions resulting in a reduced ensemble linewidth as well as single photon emission with increased purity. We furthermore investigate the temperature dependent zero-phonon-line fine-structure of a bright single SiV center as well as the polarization properties of its emission and absorption. [ABSTRACT FROM AUTHOR]

Nitrogen-vacancy (NV) centers feature outstanding properties such as a spin coherence time of up to 1 s as well as a level structure offering the possibility to initialize, coherently manipulate, and optically read-out the spin degree of freedom of the ground state. However, only about 3% of their photon emission is channeled into the zero phonon line (ZPL), limiting both the rate of indistinguishable single photons and the signal-to-noise ratio (SNR) of coherent spin-photon interfaces. We here report on the enhancement of the SNR of the optical spin read-out achieved by tuning the mode of a two-dimensional photonic crystal (PhC) cavity into resonance with the NV-ZPL. PhC cavities are fabricated by focused ion beam milling in thin reactive ion etched ultrapure single crystal diamond membranes featuring modes with Q-factors of up to 8250 at mode volumes below one cubic wavelength. NV centers are produced in the cavities in a controlled fashion by a high resolution atomic force microscope implantation technique. On cavity resonance, we observe a lifetime shortening from 9.0 ns to 8.0 ns as well as an enhancement of the ZPL emission by almost one order of magnitude. Although on resonance the collection efficiency of ZPL photons and the spin-dependent fluorescence contrast are reduced, the SNR of the optical spin read-out is almost tripled for the cavity-coupled NV centers. [ABSTRACT FROM AUTHOR]

Purpose: Outcome assessment is critical in evaluating the efficacy of orthopaedic procedures. The Foot and Ankle Outcome Score (FAOS) is a 42-item questionnaire divided into five subscales, which has been validated in several languages. Germany has no validated outcome score for general foot and ankle pathology. The aim of this study was to develop a German version of the FAOS and to investigate its psychometric properties. Materials and methods: Forward and backward translation was executed according to official guidelines. The final version of the FAOS was investigated in 150 patients with various foot and ankle disorders. All patients completed the FAOS, Short Form-36, numeric rating scales for pain and disability, and the Hannover questionnaire. The FAOS was re-administered after 1 week. Test-retest reliability, internal consistency, minimal detectable change, construct validity, and floor and ceiling effects were analyzed. Results: Test-retest reliability and internal consistency of each subscale were excellent (intraclass correlation coefficient, 0.88-0.95; Cronbach's α, 0.94-0.98). The minimal detectable changes of each subscale were 17.1-20.8 at the individual level and 2.0-2.4 at group level. There were moderate to strong correlations between FAOS subscales and physical outcomes and low to moderate correlations between FAOS subscales and mental outcomes. Floor and ceiling effects were not present. Conclusion: The German version of the FAOS is a reliable and valid instrument for use in foot and ankle patients. [ABSTRACT FROM AUTHOR]

Prostheses with single radius (SR) design were supposed to be as good as the physiological kinematic and stability of the knee. This in-vitro biomechanical study compared SR to a multiple radius (MR) design on the one hand and seven left human knee specimens were used. The SR and MR knee prosthesis where implanted with a navigation system. We measured varus/valgus deviation of the mechanical axis and the deviation of the joint-line to the epicondyle-line in different knee flexion degrees (0°, 30°, 45°, 60° and 90°) with and without 15 Nm of varus and valgus stress. Without varus/valgus-stress in all three groups (physiological knee, SR and MR prosthesis) the results were located on the varus-site. The variation of the SR was less than the MR, without being significant. Under varus and valgus stress varus/valgus axis deviation constantly grew. From 0-60° no significant deviation between the two prosthesis models was found. At 90° flexion varus/valgus deviation with the SR component was significantly (p ⩽ 0.05) smaller compared to the MR design. This in-vitro study showed that the SR prosthesis is significantly more stable in the coronal plane than the MR in higher flexion degrees. This could have an improved effect on biomechanical stability with a higher clinical function after SR-TKA. [ABSTRACT FROM AUTHOR]

The scheme of an ion trap quantum computer is described and the implementation of quantum gate operations with trapped Ca+ ions is discussed. Quantum information processing with Ca+ ions is exemplified with several recent experiments investigating entanglement of ions. PACS: 03.67.Lx, 03.67.Mn, 32.80.Pj [ABSTRACT FROM AUTHOR]

Teleportation of a quantum state encompasses the complete transfer of information from one particle to another. The complete specification of the quantum state of a system generally requires an infinite amount of information, even for simple two-level systems (qubits). Moreover, the principles of quantum mechanics dictate that any measurement on a system immediately alters its state, while yielding at most one bit of information. The transfer of a state from one system to another (by performing measurements on the first and operations on the second) might therefore appear impossible. However, it has been shown that the entangling properties of quantum mechanics, in combination with classical communication, allow quantum-state teleportation to be performed. Teleportation using pairs of entangled photons has been demonstrated, but such techniques are probabilistic, requiring post-selection of measured photons. Here, we report deterministic quantum-state teleportation between a pair of trapped calcium ions. Following closely the original proposal, we create a highly entangled pair of ions and perform a complete Bell-state measurement involving one ion from this pair and a third source ion. State reconstruction conditioned on this measurement is then performed on the other half of the entangled pair. The measured fidelity is 75%, demonstrating unequivocally the quantum nature of the process. [ABSTRACT FROM AUTHOR]