Blurring the Boundaries: Reflecting on PDS Roles and Responsibilities through Multiple Lenses

It is well documented that successful Professional Development School (PDS) initiatives are contingent on trusting relationships between the university and school districts

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

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

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

Field test of quantum key distribution in the Tokyo QKD Network

A novel secure communication network with quantum key distribution in a metropolitan area is reported. Different QKD schemes are integrated to demonstrate secure TV conferencing over a distance of 45km, stable long-term operation, and application to secure mobile phones.Comment: 21 pages, 19 figure

Heterogeneity assessment of functional T cell avidity.

The potency of cellular immune responses strongly depends on T cell avidity to antigen. Yet, functional avidity measurements are rarely performed in patients, mainly due to the technical challenges of characterizing heterogeneous T cells. The mean functional T cell avidity can be determined by the IFN-γ Elispot assay, with titrated amounts of peptide. Using this assay, we developed a method revealing the heterogeneity of functional avidity, represented by the steepness/hillslope of the peptide titration curve, documented by proof of principle experiments and mathematical modeling. Our data show that not only natural polyclonal CD8 T cell populations from cancer patients, but also monoclonal T cells differ strongly in their heterogeneity of functional avidity. Interestingly, clones and polyclonal cells displayed comparable ranges of heterogeneity. We conclude that besides the mean functional avidity, it is feasible and useful to determine its heterogeneity (hillslope) for characterizing T cell responses in basic research and patient investigation

Quantum key distribution using quantum dot single-photon emitting diodes in the red and near infrared spectral range

We report on in-lab free space quantum key distribution (QKD) experiments over 40 cm distance using highly efficient electrically driven quantum dot single-photon sources emitting in the red as well as near-infrared spectral range. In the case of infrared emitting devices, we achieve sifted key rates of 27.2 kbit s(-1)(35.4 kbit s(-1)) at a quantum bit error rate (QBER) of 3.9% (3.8%) and a g((2))(0) value of 0.35 (0.49) at moderate (high) excitation. The red emitting diodes generate sifted keys at a rate of 95.0 kbit s(-1) at a QBER of 4.1% and a g((2))(0) value of 0.49. This first successful proof of principle QKD experiment based on electrically operated semiconductor single-photon sources can be considered as a major step toward practical and efficient quantum cryptography scenarios.Publisher PDFPeer reviewe