Provably-secure quantum randomness expansion with uncharacterised homodyne detection

Quantum random number generators (QRNGs) are able to generate numbers that are certifiably random, even to an agent who holds some side-information. Such systems typically require that the elements being used are precisely calibrated and validly certified for a credible security analysis. However, this can be experimentally challenging and result in potential side-channels which could compromise the security of the QRNG. In this work, we propose, design and experimentally demonstrate a QRNG protocol that completely removes the calibration requirement for the measurement device. Moreover, our protocol is secure against quantum side-information. We also take into account the finite-size effects and remove the independent and identically distributed requirement for the measurement side. More importantly, our QRNG scheme features a simple implementation which uses only standard optical components and are readily implementable on integrated-photonic platforms. To validate the feasibility and practicability of the protocol, we set up a fibre-optical experimental system with a home-made homodyne detector with an effective efficiency of 91.7% at 1550nm. The system works at a rate of 2.5MHz, and obtains a net randomness expansion rate of 4.98kbits/s at 1E10 rounds. Our results pave the way for an integrated QRNG with self-testing feature and provable security.Comment: This is a preliminary draft, comments and suggestions are welcomed

Reactive plasma cleaning and restoration of transition metal dichalcogenide monolayers

The cleaning of two-dimensional (2D) materials is an essential step in the fabrication of future devices, leveraging their unique physical, optical, and chemical properties. Part of these emerging 2D materials are transition metal dichalcogenides (TMDs). So far there is limited understanding of the cleaning of “monolayer” TMD materials. In this study, we report on the use of downstream H2 plasma to clean the surface of monolayer WS2 grown by MOCVD. We demonstrate that high-temperature processing is essential, allowing to maximize the removal rate of polymers and to mitigate damage caused to the WS2 in the form of sulfur vacancies. We show that low temperature in situ carbonyl sulfide (OCS) soak is an efficient way to resulfurize the material, besides high-temperature H2S annealing. The cleaning processes and mechanisms elucidated in this work are tested on back-gated field-effect transistors, confirming that transport properties of WS2 devices can be maintained by the combination of H2 plasma cleaning and OCS restoration. The low-damage plasma cleaning based on H2 and OCS is very reproducible, fast (completed in a few minutes) and uses a 300 mm industrial plasma etch system qualified for standard semiconductor pilot production. This process is, therefore, expected to enable the industrial scale-up of 2D-based devices, co-integrated with silicon technology

New Rules of Refinancing and Investor Protection in China

This paper studies how the new rules of refinancing, which changed the pricing benchmark date of private placement to the approval date, influenced the impact of private placement on stock price. We find that the new rules of refinancing conveyed positive information to the market, making the announcement effect of approval date better. Meanwhile, the new rules significantly reduced the issuance discount rate and restrained the possible arbitrage behavior of major shareholders. For companies which pricing benchmark date was not the first day of the issuance, the market would form reasonable expectations of the issuance discount rate and it had a significant negative correlation with the announcement effect on the approval date. Our results show that the new rules improve the announcement effect of approval by decreasing the discount rate of private placement, and strengthen the protection of investors’ interests

Provably-secure quantum randomness expansion with uncharacterised homodyne detection

Quantum random number generators should ideally rely on few assumptions, have high enough generation rates, and be cost-effective and easy to operate. Here, the authors show an untrusted-homodyne-based MDI scheme that does not rely on i.i.d. assumption and is secure against quantum side information

Further exploring solvent-exposed tolerant regions of allosteric binding pocket for novel HIV-1 NNRTIs discovery

Based on the detailed analysis of the binding mode of diarylpyrimidines (DAPYs) with HIV-1 RT, we designed several subseries of novel NNRTIs, with the aim to probe biologically relevant chemical space of solvent-exposed tolerant regions in NNRTIs binding pocket (NNIBP). The most potent compound exhibited significant activity against the whole viral panel, being about 1.5-2.6-fold (WT, EC = 2.44 nM; L100I, EC = 4.24 nM; Y181C, EC = 4.80 nM; F227L + V106A, EC = 17.8 nM) and 4-5-fold (K103N, EC = 1.03 nM; Y188L, EC = 7.16 nM; E138K, EC = 3.95 nM) more potent than the reference drug ETV. Furthermore, molecular simulation was conducted to understand the binding mode of interactions of these novel NNRTIs and to provide insights for the next optimization studies.status: publishe

Reactive plasma cleaning and restoration of transition metal dichalcogenide monolayers

The cleaning of two-dimensional (2D) materials is an essential step in the fabrication of future devices, leveraging their unique physical, optical, and chemical properties. Part of these emerging 2D materials are transition metal dichalcogenides (TMDs). So far there is limited understanding of the cleaning of “monolayer” TMD materials. In this study, we report on the use of downstream H2 plasma to clean the surface of monolayer WS2 grown by MOCVD. We demonstrate that high-temperature processing is essential, allowing to maximize the removal rate of polymers and to mitigate damage caused to the WS2 in the form of sulfur vacancies. We show that low temperature in situ carbonyl sulfide (OCS) soak is an efficient way to resulfurize the material, besides high-temperature H2S annealing. The cleaning processes and mechanisms elucidated in this work are tested on back-gated field-effect transistors, confirming that transport properties of WS2 devices can be maintained by the combination of H2 plasma cleaning and OCS restoration. The low-damage plasma cleaning based on H2 and OCS is very reproducible, fast (completed in a few minutes) and uses a 300 mm industrial plasma etch system qualified for standard semiconductor pilot production. This process is, therefore, expected to enable the industrial scale-up of 2D-based devices, co-integrated with silicon technology