Large-scale integrated quantum photonic technologies will require on-chip integration of identical photon sources with reconfigurable waveguide circuits. Relatively complex quantum circuits have been ...demonstrated already, but few studies acknowledge the pressing need to integrate photon sources and waveguide circuits together on-chip. A key step towards such large-scale quantum technologies is the integration of just two individual photon sources within a waveguide circuit, and the demonstration of high-visibility quantum interference between them. Here, we report a silicon-on-insulator device that combines two four-wave mixing sources in an interferometer with a reconfigurable phase shifter. We configured the device to create and manipulate two-colour (non-degenerate) or same-colour (degenerate) path-entangled or path-unentangled photon pairs. We observed up to 100.0 ± 0.4% visibility quantum interference on-chip, and up to 95 ± 4% off-chip. Our device removes the need for external photon sources, provides a path to increasing the complexity of quantum photonic circuits and is a first step towards fully integrated quantum technologies.
Intersubband transition (ISBT) in GaN quantum wells (QWs) was investigated from the viewpoint of application to ultrafast all-optical switches. The effect of crystalline quality on the absorption ...saturation characteristics was examined and reduction of edge dislocations was found to be a crucial factor in decreasing operation energy. Then, the switching performance was investigated for devices with improved crystalline quality. Modulation of signal pulses with a pulse interval of less than 1 ps was confirmed. Another device displayed gate-switch operation with an extinction ratio of greater than 10 dB. Comparison of the absorption recovery process in both devices suggested that the process is strongly affected by the QW structure
Integrated quantum photonic waveguide circuits are a promising approach to realizing future photonic quantum technologies. Here, we present an integrated photonic quantum technology platform ...utilizing the silicon-on-insulator material system, where quantum interference and the manipulation of quantum states of light are demonstrated in components orders of magnitude smaller than previous implementations. Two-photon quantum interference is presented in a multi-mode interference coupler, and the manipulation of entanglement is demonstrated in a Mach-Zehnder interferometer, opening the way to an all-silicon photonic quantum technology platform.
A number of heating sources are available for minimally invasive thermal therapy of tumours. The purpose of this work was to compare, theoretically, the heating characteristics of interstitial ...microwave, laser and ultrasound sources in three tissue sites: breast, brain and liver. Using a numerical method, the heating patterns, temperature profiles and expected volumes of thermal damage were calculated during standard treatment times with the condition that tissue temperatures were not permitted to rise above 100 degrees C (to ensure tissue vaporization did not occur). Ideal spherical and cylindrical applicators (200 microm and 800 microm radii respectively) were modelled for each energy source to demonstrate the relative importance of geometry and energy attenuation in determining heating and thermal damage profiles. The theoretical model included the effects of the collapse of perfusion due to heating. Heating patterns were less dependent on the energy source when small spherical applicators were modelled than for larger cylindrical applicators due to the very rapid geometrical decrease in energy with distance for the spherical applicators. For larger cylindrical applicators, the energy source was of greater importance. In this case, the energy source with the lowest attenuation coefficient was predicted to produce the largest volume of thermally coagulated tissue, in each tissue site.
In a previous study, we showed that levels of cell-free DNA (cfDNA) were significantly higher in sera of patients with hepatocellular carcinoma (HCC) associated with hepatitis C virus (HCV) than in ...sera of non-HCC patients with HCV. To confirm this finding, we analysed serum cfDNA levels in a cohort of 96 patients with HCV-related HCC and in 100 HCV carriers without known HCC. Again we found that serum cfDNA levels were significantly higher in HCC patients than in HCV carriers (115.9+/-98.3 vs 34.4+/-40.4 ng ml(-1) (mean+/-s.d.), P<0.0001). Of 87 eligible patients who underwent curative hepatectomy, those with a high cfDNA level had a significantly shorter overall survival (OS) time than those in whom the cfDNA level was not high. Cox proportional hazards model showed the cfDNA level to be an independent prognostic factor for OS and cancer recurrence in distant organs. Our results suggest that the serum cfDNA level reflects the metastatic potential of HCV-related HCC and that it can be a useful predictive biomarker for distant metastasis after curative surgery.
A nonlinear mathematical model was developed and experimentally validated to investigate the effects of changes in optical properties during interstitial laser photocoagulation (ILP). The effects of ...dynamic optical properties were calculated using the Arrhenius damage model, resulting in a nonlinear optothermal response. This response was experimentally validated by measuring the temperature rise in albumen and polyacrylamide phantoms. A theoretical study of ILP in liver was conducted constraining the peak temperatures below the vaporization threshold. The temperature predictions varied considerably between the static and dynamic scenarios, and were confirmed experimentally in phantoms. This suggests that the Arrhenius model can be used to predict dynamic changes in optical and thermal fields. An increase in temperature rise due to a decrease in light penetration within the coagulated region during ILP of the liver was also demonstrated. The kinetics of ILP are complex and nonlinear due to coagulation, which changes the tissue properties during treatment. These complex effects can be adequately modelled using an Arrhenius damage formulation.
Using oligonucleotide microarray data of 45 hepatocellular carcinoma (HCC) samples, we evaluated gene expression in hepatitis B virus-positive and hepatitis C virus-positive HCCs (HBV- and HCV-HCCs) ...for an association with liver cirrhosis (LC). In all, 89 genes were expressed differentially between HBV-HCCs associated with LC and those not associated with LC. Among them, tumors from LC patients showed significantly lower expression levels of 72 genes and significantly higher levels of 17 genes than the levels found in tumors from non-LC patients. The former included genes responsible for signal transduction, transcription, metabolism, and cell growth. The latter included a tumor suppressor gene and a cell-growth-related gene. Only eight genes were expressed differentially between HCV-HCCs associated with and without LC. Our findings provide as a framework for clarifying the role of LC in HBV- and HCV-related hepatocarcinogenesis.
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