Waveguide-integrated silicon T centres.

The performance of modular, networked quantum technologies will be strongly dependent upon the quality of their quantum light-matter interconnects. Solid-state colour centres, and in particular T centres in silicon, offer competitive technological and commercial advantages as the basis for quantum networking technologies and distributed quantum computing. These newly rediscovered silicon defects offer direct telecommunications-band photonic emission, long-lived electron and nuclear spin qubits, and proven native integration into industry-standard, CMOS-compatible, silicon-on-insulator (SOI) photonic chips at scale. Here we demonstrate further levels of integration by characterizing T centre spin ensembles in single-mode waveguides in SOI. In addition to measuring long spin T1 times, we report on the integrated centres' optical properties. We find that the narrow homogeneous linewidth of these waveguide-integrated emitters is already sufficiently low to predict the future success of remote spin-entangling protocols with only modest cavity Purcell enhancements. We show that further improvements may still be possible by measuring nearly lifetime-limited homogeneous linewidths in isotopically pure bulk crystals. In each case the measured linewidths are more than an order of magnitude lower than previously reported and further support the view that high-performance, large-scale distributed quantum technologies based upon T centres in silicon may be attainable in the near term.

Inductive measurement of optically hyperpolarized phosphorous donor nuclei in an isotopically enriched silicon-28 crystal.

We experimentally demonstrate the first inductive readout of optically hyperpolarized phosphorus-31 donor nuclear spins in an isotopically enriched silicon-28 crystal. The concentration of phosphorus donors in the crystal was 1.5×10(15) cm(-3), 3 orders of magnitude lower than has previously been detected via direct inductive detection. The signal-to-noise ratio measured in a single free induction decay from a 1 cm(3) sample (≈10(15) spins) was 113. By transferring the sample to an X-band ESR spectrometer, we were able to obtain a lower bound for the nuclear spin polarization at 1.7 K of ∼64%. The (31)P-T2 measured with a Hahn echo sequence was 420 ms at 1.7 K, which was extended to 1.2 s with a Carr Purcell cycle. The T1 of the (31)P nuclear spins at 1.7 K is extremely long and could not be determined, as no decay was observed even on a time scale of 4.5 h. Optical excitation was performed with a 1047 nm laser, which provided above-band-gap excitation of the silicon. The buildup of the hyperpolarization at 4.2 K followed a single exponential with a characteristic time of 577 s, while the buildup at 1.7 K showed biexponential behavior with characteristic time constants of 578 and 5670 s.

Quantum information storage for over 180 s using donor spins in a 28Si "semiconductor vacuum".

A quantum computer requires systems that are isolated from their environment, but can be integrated into devices, and whose states can be measured with high accuracy. Nuclear spins in solids promise long coherence lifetimes, but they are difficult to initialize into known states and to detect with high sensitivity. We show how the distinctive optical properties of enriched (28)Si enable the use of hyperfine-resolved optical transitions, as previously applied to great effect for isolated atoms and ions in vacuum. Together with efficient Auger photoionization, these resolved hyperfine transitions permit rapid nuclear hyperpolarization and electrical spin-readout. We combine these techniques to detect nuclear magnetic resonance from dilute (31)P in the purest available sample of (28)Si, at concentrations inaccessible to conventional measurements, measuring a solid-state coherence time of over 180 seconds.

[Pressure-related dysphonia, recurring pneumonia and supraglottic tumor]. / Belastungsabhängige Dysphonie, rezidivierende Pleuropneumonie und supraglottische Raumforderung.

Urbach-Wiethe syndrome (hyalinosis cutis et mucosae) is an autosomal-recessive inherited disease. It often presents with typical symptoms such as skin lesions (especially in the face and neck area), dyspnea, and maldigestion. Hoarseness is a leading symptom in young children. These manifestations are caused by the assimilation of glycoproteins in mesenchymal tissue. Our case report shows that hoarseness does not necessarily appear only in children, but can also appear later. Furthermore, the assimilation of glycoproteins in the supraglottic area may also cause dysphonia. Due to the varied features of this disease, interdisciplinary check-ups are necessary at regular intervals.

Simultaneous subsecond hyperpolarization of the nuclear and electron spins of phosphorus in silicon by optical pumping of exciton transitions.

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

Reduction of the linewidths of deep luminescence centers in 28Si reveals fingerprints of the isotope constituents.

Dramatic reductions of the linewidths of well-known deep centers in 28Si reveal "isotopic fingerprints" of the constituents. The approximately 1014 meV Cu center, thought to be either a Cu pair or an isolated Cu, is shown to contain four Cu atoms, and the approximately 780 meV Ag center is shown to contain four Ag. The approximately 944 meV ;{*}Cu center, thought to be a different configuration of a Cu pair, in fact contains three Cu and one Ag, and a new two-Cu two-Ag center is found. The approximately 735 meV center, previously assigned to Fe, actually contains Au and three Cu. This suggests a family of four-atom (Cu, Ag, Au) centers.

Optical detection and ionization of donors in specific electronic and nuclear spin States.

We resolve the remarkably sharp bound exciton transitions of highly enriched 28Si using a single-frequency laser and photoluminescence excitation spectroscopy, as well as photocurrent spectroscopy. Well-resolved doublets in the spectrum of the 31P donor reflect the hyperfine coupling of the electronic and nuclear donor spins. The optical detection of the nuclear spin state, and selective pumping and ionization of donors in specific electronic and nuclear spin states, suggests a number of new possibilities which could be useful for the realization of silicon-based quantum computers.

[PET/CT imaging in head and neck tumors]. / PET-CT-Bildgebung bei Kopf-Hals-Tumoren.

AIM: To evaluate the usefulness of combined PET/CT examinations for detection of malignant tumors and their metastases in head and neck oncology. METHODS: 51 patients received whole body scans on a dual modality PET/CT system. CT was performed without i.v. contrast. The results were compared concerning the diagnostic impact of native CT scan on FDG-PET images and the additional value of fused imaging. RESULTS: From 153 lesions were 97 classified as malignant on CT and 136 on FDG/PET images, as suspicious for malignancy in 33 on CT and 7 on FDG-PET and as benign in 23 on CT and 10 on FDG-PET. With combined PET/CT all primary and recurrent tumors could be found, the detection rate in patients with unknown primary tumors was 45%. Compared to PET or CT alone the sensitivity, specifity and accuracy could be significantly improved by means of combined PET/CT. CONCLUSION: Fused PET/CT imaging with [F18]-FDG and native CT-scanning enables accurate diagnosis in 93% of lesions and 90% of patients with head and neck oncology.

Photoluminescence of isotopically purified silicon: how sharp are bound exciton transitions?

We report the first high resolution photoluminescence studies of isotopically pure Si (99.896% (28)Si). New information is obtained on isotopic effects on the indirect band gap energy, phonon energies, and phonon broadenings, which is in good agreement with calculations and previous results obtained in Ge and diamond. Remarkably, the linewidths of the no-phonon boron and phosphorus bound exciton transitions in the (28)Si sample are much narrower than in natural Si and are not well resolved at our maximum instrumental resolution of approximately 0.014 cm(-1). The removal of the dominant broadening resulting from isotopic randomness in natural Si reveals new fine structure in the boron bound exciton luminescence.

Craniometaphyseal dysplasia as a rare cause of a severe neonatal nasal obstruction.

We report on a 2-year-9-month-old boy with the typical features of craniometaphyseal dysplasia with hyperostosis and sclerosis of the cranial vault and mild splaying of the metaphyses. The boy already presented during the neonatal period with the unusual clinical picture of breathing and feeding problems due to severely enlarged and ossified inferior nasal conchae causing obstruction of the nasal lumen.

[Ultrasonic diagnosis of goiter of the tongue base]. / Die sonographische Diagnose von Zungengrundstrumen.

Lingual goitre was found in two adolescents suffering from mild dysphagia. Since there were typical changes in lingual sonomorphology, sonographic evaluation was easy to perform. Lingual thyroid was less echogenic than normal thyroid tissue. Ultrasound may support the decision of the initial treatment and is useful to guide further therapy.

[A difficult intubation in a case of endolaryngeal paraganglioma]. / Erschwerte Intubation bei endolaryngealem Paragangliom.

In a female patient aged 71, a tumor of unknown histology almost completely occupied the whole of the supraglottic space. Because of the valve-like behaviour of the tumor, the patient could not be ventilated by mask. Therefore, preoxygenation and preservation of spontaneous breathing were essential. Anaesthesia was induced by titration of etomidate, and no muscle relaxant or opioid was administered. The patient was successfully intubated by means of direct laryngoscopy. In all probability the blind nasal technique or the use of a fiberoptic device would not have been helpful, because the tumor had to be luxated before the endotracheal tube could be placed. Figure 1 shows the tumor (a) with a diameter of approximately 3 cm, which has displaced the epiglottis (b) to the left. A part of the endotracheal tube is visible at the bottom left. The spiral tube had to be replaced by a tube suitable for laser surgery. After resection (see Fig. 2) the coagulated tumor base (a) and the right vocal cord (b) can be seen with the laser tube still in place. Postoperatively extubation was possible. The histological examination revealed a paraganglioma without signs of malignancy. Apart from occlusion of the upper airway, the main danger stems from the considerable vascularization of such a paraganglioma. Not only the surgical procedure, but also minor manipulations during the endotracheal intubation may cause significant blood loss. In a small percentage of cases hormone-mediated cardiocirculatory complications may occur. If a difficult intubation is expected because of an endolaryngeal tumor, management should be based on the diagnostic findings and the planned surgical procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

[High-resolution computed tomography in diseases of the inner ear]. / Hochauflösende Computertomographie bei Erkrankungen des Innenohres.

High-resolution CT of the petrous bone was carried out in 259 patients with clinically diagnosed abnormalities of the inner ear; in some the lesions were bilateral. In 62 patients (approximately 20%), the scans showed findings which related to the signs and symptoms. Patients with hearing loss and vestibular neuronitis showed no abnormalities. Amongst the remaining patients, the most common findings were acoustic neuromas (17 cases), cochlear otospongiosis (14 cases), malformations (13 cases) and tumours or cholesteatomas of the labyrinth (13 cases) as well as single rare isolated lesions.

[Chondroma of the larynx--case report and differential diagnosis in CT]. / Chondrom des Larynx--Falldarstellung und Differentialdiagnose in der CT.

The characteristic features of chondroma and chondrosarcoma of the larynx (less than 1% of laryngeal tumors) are discussed in a case report. Laryngoscopy (rounded, smooth tumor, covered by normal mucous membrane) and HR-CT of the larynx (swelling of the cartilages, calcifications in 80% of cases) give a characteristic view of the tumor, so that, by synopsis of both, a definite diagnostic statement concerning the kind of tumor is possible. However, carcinoma of the larynx with invasion of the cartilage, laryngeal manifestation of multiple chondromatosis and calcification after severe trauma have to be differentiated from cartilaginous tumors of the larynx. The adequate therapy of chondroma and low-grade chondrosarcoma consists of partial laryngectomy and reconstruction of the air passages. High-grade chondrosarcoma should be treated with radical laryngectomy.

[Computed tomography in the preoperative diagnosis of malignant laryngeal tumors]. / Die Computertomographie in der präoperativen Diagnostik von malignen Larynxtumoren.

The pre-operative laryngoscopic and CT findings in the larynx in 50 patients with malignant laryngeal tumours were compared. Laryngoscopy showed an accuracy for T-staging of 78.6% and CT an accuracy of 80%. In addition, CT complemented the endoscopic findings by demonstrating the depth of tumour invasion. The changes in individual anatomical portions of the larynx were compared, using both methods. CT and palpation showed equal specificity for lymph node staging, but CT is markedly superior in sensitivity.

[Dacryocystography in the digital subtraction technic]. / Dakryozystographie in digitaler Subtraktionstechnik.

Dacryocystorhinostomy is well established as a common surgical approach to the treatment of obstructive epiphora. The importance of a radiological procedure for pre-operative diagnosis and postoperative follow-up is emphasised. Routine imaging (dacryocystography) of the nasolacrimal system is made difficult by the high contrast between bone and air in the sinuses and pharynx, by overlapping structures, and by the very small size of those structures that are of interest. Digital subtraction technique provides significantly improved visualisation even of poorly contrasted structures of the lacrimal system (i.e. canaliculi lacrimales), overcoming limitations imposed by inherently high object contrast. Representative case reports such as pre- and postsaccal stenosis and functional obstruction are presented. Digital subtraction dacryocystography is an important nonvascular application of digital imaging technology.

[Radiation therapy of nasopharyngeal carcinoma. Retrospective study for the assessment of long-term results]. / Strahlentherapie des Nasopharynxkarzinoms. Folgestudie zur Beurteilung der Langzeitergebnisse.

During the years from 1967 to 1986, 90 patients with nasopharyngeal carcinomas were irradiated at the Radiologic Hospital of Bonn University. The median overall survival time was 4.3 years which corresponded to 23% of the statistical life expectancy of the patients. 66% were still alive after two years and 46.5% after five years. Compared to the overall group, the prognosis was significantly worse in case of highly differentiated, keratinizing squamous cell carcinomas, penetration of the primary tumor into the base of the skull, or certain symptoms as ophthalmo-neurologic troubles, headaches, loss of body weight, night sweat, or fever. After partial tumor excision performed prior to irradiation or complete remission following to radiotherapy, the therapy results were better than the average with median survival times of about eleven years.

[High-resolution computed tomography in malformations of the cochlear and vestibular organs]. / Hochauflösende Computertomographie bei Missbildungen des Gehör- und Gleichgewichtsorganes.

Twenty-one patients with congenital deformities of the petrous bones were examined by high resolution computed tomography. This allows an accurate description of the extent of the malformation in all parts of the cochlear and vestibular organs; only localised changes in the auditory ossicles, such as fixation of the stapes and changes in the soft tissue portions of the labyrinth, cannot be shown. Improved demonstration of soft tissues while using less radiation makes high resolution CT preferable to conventional polytomography. It is also easier to perform and provides axial projections which are essential for the elucidation of malformations of the middle and inner ear.

[Malignant tumors of the mouth and pharynx--MR tomography with surface coils]. / Malignome der Mundhöhle und des Pharynx--MR-Tomographie mit Oberflächenspulen.

The place of MRT, using surface coils, has been evaluated retrospectively in 27 patients with clinically confirmed malignant tumours of the mouth and pharynx. The extent of the tumour and its relationship to neighbouring structures is well demonstrated. The resolution obtainable by using surface coils is almost as good as that of CT. Soft tissue contrast is better in showing the spread and size of the tumour. A disadvantage of MRT is the inability in most cases to demonstrate bone destruction. Differentiation between residual tumour, recurrence and scarring is possible only occasionally. Quantitative MRT may be expected to lead to improved diagnosis during the course of following up.