Device calibration impacts security of quantum key distribution

Characterizing the physical channel and calibrating the cryptosystem hardware are prerequisites for establishing a quantum channel for quantum key distribution (QKD). Moreover, an inappropriately implemented calibration routine can open a fatal security loophole. We propose and experimentally demonstrate a method to induce a large temporal detector efficiency mismatch in a commercial QKD system by deceiving a channel length calibration routine. We then devise an optimal and realistic strategy using faked states to break the security of the cryptosystem. A fix for this loophole is also suggested.Comment: 4 pages + 1 page of supplementary information. Considerable modification of Eve's attack strategy and QBER minimization technique. All figures have also been improve

Hacking commercial quantum cryptography systems by tailored bright illumination

The peculiar properties of quantum mechanics allow two remote parties to communicate a private, secret key, which is protected from eavesdropping by the laws of physics. So-called quantum key distribution (QKD) implementations always rely on detectors to measure the relevant quantum property of single photons. Here we demonstrate experimentally that the detectors in two commercially available QKD systems can be fully remote-controlled using specially tailored bright illumination. This makes it possible to tracelessly acquire the full secret key; we propose an eavesdropping apparatus built of off-the-shelf components. The loophole is likely to be present in most QKD systems using avalanche photodiodes to detect single photons. We believe that our findings are crucial for strengthening the security of practical QKD, by identifying and patching technological deficiencies.Comment: Revised version, rewritten for clarity. 5 pages, 5 figures. To download the Supplementary information (which is in open access), go to the journal web site at http://dx.doi.org/10.1038/nphoton.2010.21

Full-field implementation of a perfect eavesdropper on a quantum cryptography system

Quantum key distribution (QKD) allows two remote parties to grow a shared secret key. Its security is founded on the principles of quantum mechanics, but in reality it significantly relies on the physical implementation. Technological imperfections of QKD systems have been previously explored, but no attack on an established QKD connection has been realized so far. Here we show the first full-field implementation of a complete attack on a running QKD connection. An installed eavesdropper obtains the entire 'secret' key, while none of the parameters monitored by the legitimate parties indicate a security breach. This confirms that non-idealities in physical implementations of QKD can be fully practically exploitable, and must be given increased scrutiny if quantum cryptography is to become highly secure.Comment: Revised after editorial and peer-review feedback. This version is published in Nat. Commun. 8 pages, 6 figures, 1 tabl

Quantum Eavesdropping without Interception: An Attack Exploiting the Dead Time of Single Photon Detectors

The security of quantum key distribution (QKD) can easily be obscured if the eavesdropper can utilize technical imperfections of the actual implementation. Here we describe and experimentally demonstrate a very simple but highly effective attack which even does not need to intercept the quantum channel at all. Only by exploiting the dead time effect of single photon detectors the eavesdropper is able to gain (asymptotically) full information about the generated keys without being detected by state-of-the-art QKD protocols. In our experiment, the eavesdropper inferred up to 98.8% of the key correctly, without increasing the bit error rate between Alice and Bob significantly. Yet, we find an evenly simple and effective countermeasure to inhibit this and similar attacks

Unraveling disruptions: how employees pick up signals of change

Psychological contracts reside in the eye of the beholder and capture the employee-employer exchange relationship. It is a dynamic relationship as employees deliberately manage and change their psychological contract over time. Triggers seem to be the drivers underpinning this dynamism. Yet little is known about how these triggers operate and affect the psychological contract. To address this, we explore triggers and their impact using a 6-week daily diary study (N = 117). We found a linear chain of positive relationships from initial triggers to connectedness of past triggers, to the experience of negative emotions, to the expected reoccurrence of the initial trigger, ultimately disrupting the psychological contract. The findings revealed the dynamic effect of triggers on the employment relationship, not only by exposing the underlying micro-processes, but also by revealing that the impact of triggers can linger for approximately 11 days before leveling off. These findings suggest that the psychological contract may fluctuate on a daily basis due to the influence of triggers. The theoretical implications for understanding the dynamic nature of the psychological contract are discussed in relation to the disruptive role of triggers

Atomic-scale perspective on individual thiol-terminated molecules anchored to single S vacancies in MoS₂

Sulfur vacancies in MoS2 on Au(111) have been shown to be negatively charged as reflected by a Kondo resonance. Here, we use scanning tunneling microscopy to show that these vacancies serve as anchoring sites for thiol-based molecules (CF3−3⁢P−SH) with two distinct reaction products, one of them showing a Kondo resonance. Based on comparisons with density-functional theory (DFT) calculations, including a random structure search and computation of energies and electronic properties at a hybrid exchange-correlation functional level, we conclude that both anchored molecules are charge neutral. We propose that one of them is an anchored intact CF2−3⁢P−SH molecule while the other one is the result of catalytically activated dehydrogenation to CF2−3⁢P−S with subsequent anchoring. Our investigations highlight a perspective of functionalizing defects with thiol-terminated molecules that can be equipped with additional functional groups, such as charge donor or acceptor moieties, switching units, or magnetic centers

Razvoj matriksnih sustava za transdermalnu isporuku pentazocina: In vitro/in vivo ispitivanje

The present study aimed to develop hydroxypropyl methylcellulose based transdermal delivery of pentazocine. In formulations containing lower proportions of polymer, the drug released followed the Higuchi kinetics while, with an increase in polymer content, it followed the zero-order release kinetics. Release exponent (n) values imply that the release of pentazocine from matrices was non-Fickian. FT-IR, DSC and XRD studies indicated no interaction between drug and polymer. The in vitro dissolution rate constant, dissolution half-life and pharmacokinetic parameters (Cmax, tmax, AUC(s), t1/2, Kel, and MRT) were evaluated statistically by two-way ANOVA. A significant difference was observed between but not within the tested products. Statistically, a good correlation was found between per cent of drug absorbed from patches vs. Cmax, and AUC(s). A good correlation was also observed when per cent drug released was correlated with the blood drug concentration obtained at the same time point. The results of this study indicate that the polymeric matrix films of pentazocine hold potential for transdermal drug delivery.U radu je opisan razvoj transdermalnih sustava na bazi hidroksipropil metilceluloze za isporuku pentazocina. U pripravcima koji sadrže manje udjele polimera, otpuštanje lijeka slijedilo je Higuchijevu kinetiku. Međutim, ako je udio polimera veći oslobađanje je najbolje odgovaralo kinetici nultog reda. Vrijednost eksponenta n implicira da oslobađanje pentazocina iz matriksa nije po Fickovom zakonu. FT-IR, DSC i X RD studije ukazuju da nema interakcije između ljekovite tvari i polimera. In vitro konstanta oslobađanja, poluvrijeme oslobađanja i farmakokinetički parametri (Cmax, tmax, AUC(s), t1/2, Kel, i MRT) procijenjeni su statistički koristeći ANOVA program. Značajna razlika primijećena je između, ali ne i unutar testiranih pripravaka. Pronađena je dobra korelacija između lijeka apsorbiranog iz flastera i Cmax i AUC(s) te oslobođenog lijeka i koncentracije lijeka u krvi. Rezultati ukazuju da su polimerni matriksni filmovi pentazocina potencijalno dobri sustavi za transdermalnu primjenu lijeka

Controlling a superconducting nanowire single-photon detector using tailored bright illumination

We experimentally demonstrate that a superconducting nanowire single-photon detector is deterministically controllable by bright illumination. We found that bright light can temporarily make a large fraction of the nanowire length normally-conductive, can extend deadtime after a normal photon detection, and can cause a hotspot formation during the deadtime with a highly nonlinear sensitivity. In result, although based on different physics, the superconducting detector turns out to be controllable by virtually the same techniques as avalanche photodiode detectors. As demonstrated earlier, when such detectors are used in a quantum key distribution system, this allows an eavesdropper to launch a detector control attack to capture the full secret key without being revealed by to many errors in the key.Comment: Expanded discussions, updated references. 9 pages, 8 figure

Intravitreal bevacizumab (Avastin®) for diabetic retinopathy at 24-months: The 2008 Juan Verdaguer-planas lecture

Diabetic retinopathy (DR) remains the major threat to sight in the working age population. Diabetic macular edema (DME) is a manifestation of DR that produces loss of central vision. Proliferative diabetic retinopathy (PDR) is a major cause of visual loss in diabetic patients. In PDR, the growth of new vessels is thought to occur as a result of vascular endothelial growth factor (VEGF) release into the vitreous cavity as a response to ischemia. Furthermore, VEGF increases vessel permeability leading to deposition of proteins in the interstitium that facilitate the process of angiogenesis and macular edema. This review demonstrates multiple benefits of intravitreal bevacizumab (IVB) on DR including DME and PDR at 24 months of follow up. The results indicate that IVB injections may have a beneficial effect on macular thickness and visual acuity (VA) in diffuse diabetic macular edema. Therefore, in the future this new therapy could replace or complement focal/grid laser photocoagulation in DME. In PDR, this new option could be an adjuvant agent to pan-retina photocoagulation so that more selective therapy may be applied. In addition, we report a series of patients in which tractional retinal detachment developed or progressed after adjuvant preoperative IVB in severe PDR. © 2010 Bentham Science Publishers Ltd

Neutrino Mixing from Wilson Lines in Warped Space

We consider the generation of the hierarchical charged lepton spectrum and anarchic neutrino masses and mixing angles in warped extra dimensional models with Randall-Sundrum metric. We have classified all possible cases giving rise to realistic spectra for both Dirac and Majorana neutrinos. An anarchic neutrino spectrum requires a convenient bulk symmetry broken by boundary conditions on both UV and IR branes. We have in particular considered the case of Majorana neutrinos with a continuous bulk symmetry. To avoid unwanted massless extra gauge bosons the 4D group should be empty. If the 4D coset is not vanishing it can provide a Wilson Line description of the neutrino Majorana mass matrix. We have studied an example based on the bulk gauge group U(3)_{L} \otimes U(3)_{N} \otimes_{i} U(1)_{E^i} with the Wilson Line in SO(3)_{N} satisfying all required conditions. A \chi^2-fit to experimental data exhibits the 95% CL region in the parameter space with no fine-tuning. As a consequence of the symmetries of the theory there is no tree-level induced lepton flavor violation and so one-loop processes are consistent with experimental data for KK-modes about a few TeV. The model is easily generalizable to models with IR deformed metrics with similar conclusions.Comment: 28 pages, 9 eps plots, uses axodraw; v2 Title changed, comments on phenomenology added, version to be published in JHE