Atomic-scale authentication using resonant tunnelling diodes

The rapid development of technology has provided a wealth of resources enabling the trust of everyday interactions to be undermined. Authentication schemes aim to address this challenge by providing proof of identity. This can be achieved by using devices that, when challenged, give unique but reproducible responses. At present, these distinct signatures are commonly generated by physically unclonable functions, or PUFs. These devices provide a straightforward measurement of a physical characteristic of their structure that has inherent randomness, due to imperfections in the manufacturing process. These hard-to-predict physical responses can generate a unique identity that can be used for authentication without relying on the secrecy of stored data. However, the classical design of these devices limits both their size and security. Here we show that the extensively studied problematic fluctuations in the current-voltage measurements of resonant tunnelling diodes (RTDs) provide an uncomplicated, robust measurement that can function as a PUF without conventional resource limitations. This is possible due to quantum tunnelling within the RTD, and on account of these room temperature quantum effects, we term such devices QUFs - quantum unclonable functions. As a result of the current-voltage spectra being dependent on the atomic structure and composition of the nanostructure within the RTD, each device provides a high degree of uniqueness, whilst being impossible to clone or simulate, even with state-of-the-art technology. We have thus created PUF-like devices requiring the fewest resources which make use of quantum phenomena in a highly manufacturable electronic device operating at room temperature. Conventional spectral analysis techniques, when applied to our QUFs, will enable reliable generation of unpredictable unique identities which can be employed in advanced authentication systems

Electron-paramagnetic-resonance identification of silver centers in silicon

©19xx American Physical Societ

High levels of soluble TNF superfamily receptors in patients with hepatitis C virus infection and lymphoproliferative disorders.

BACKGROUND: Chronic hepatitis C virus (HCV) infection is associated with a variety of extrahepatic disorders that may relate to direct or indirect effects of virus infection. Increased levels of soluble forms of tumor necrosis factor (TNF) receptors I and II, found in lymphoproliferative and infectious diseases, can interfere with TNF induced apoptotic cell death. The aim of the present study was to evaluate soluble TNF family receptors levels in lymphoproliferative disorders associated with HCV infection. METHODS: One hundred and forty-nine subjects were studied, including 120 anti-HCV positive patients (60 without lymphoproliferative manifestations, 47 with type II cryoglobulinemia and 13 with low-grade B-cell non-Hodgkin's lymphoma (B-NHL)) and 29 anti-HCV negative subjects (19 with low-grade B-NHLs and ten normal controls). RESULTS: Soluble forms of TNF receptor I, TNF receptor II and Fas were significantly higher in HCV positive patients compared with normal controls. The highest levels were found in patients affected by type II cryoglobulinemia or HCV positive lymphoplasmacytoid lymphomas (LP-NHLs), while HCV positive patients without type II cryoglobulinemia or with other B-NHLs had lower values (P < 0.01). CONCLUSIONS: Among HCV infected individuals, very high levels of soluble TNF receptors are significantly associated with type II cryoglobulinemia and LP-NHLs, suggesting that they may be involved in these proliferative disorders

Enhancement of efficiency of InGaN-based light emitting diodes through strain and piezoelectric field management

We report calculations of the strain dependence of the piezoelectric field within InGaN multi-quantum wells light emitting diodes. Such fields are well known to be a strong limiting factor of the device performance. By taking into account the nonlinear piezoelectric coefficients, which in particular cases predict opposite trends compared to the commonly used linear coefficients, a significant improvement of the spontaneous emission rate can be achieved as a result of a reduction of the internal field. We propose that such reduction of the field can be obtained by including a metamorphic InGaN layer below the multiple quantum well active region. © 2013 AIP Publishing LLC