Vitus Händchen

Stable control of 10 dB two-mode squeezed vacuum states of light

Continuous variable entanglement is a fundamental resource for many quantum information tasks. Important protocols like superactivation of zero-capacity channels and finite-size quantum cryptography that provides security against most general attacks, require about 10 dB two-mode squeezing. Additionally, stable phase control mechanisms are necessary but are difficult to achieve because the total amount of optical loss to the entangled beams needs to be small. Here, we experimentally demonstrate a control scheme for two-mode squeezed vacuum states at the telecommunication wavelength of 1550 nm. Our states exhibited an Einstein-Podolsky-Rosen covariance product of 0.0309 ± 0.0002, where 1 is the critical value, and a Duan inseparability value of 0.360 ± 0.001, where 4 is the critical value. The latter corresponds to 10.45 ± 0.01 dB which reflects the average non-classical noise suppression of the two squeezed vacuum states used to generate the entanglement. With the results of this work demanding quantum information protocols will become feasible.

Implementation of continuous-variable quantum key distribution with composable and one-sided-device-independent security against coherent attacks.

Tobias Gehring, 2 Vitus Händchen, Jörg Duhme, Fabian Furrer, Torsten Franz, 5 Christoph Pacher, Reinhard F. Werner, and Roman Schnabel 7, ∗ Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) and Institut für Gravitationsphysik, Leibniz Universität Hannover, Callinstraße 38, 30167 Hannover, Germany Department of Physics, Technical University of Denmark, Fysikvej, 2800 Kgs. Lyngby, Denmark Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannnover, Germany Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan, 113-0033 Institut für Fachdidaktik der Naturwissenschaften, Technische Universität Braunschweig, Bienroder Weg 82, 38106 Braunschweig, Germany Digital Safety & Security Department, AIT Austrian Institute of Technology GmbH, 1220 Vienna, Austria Institut für Laserphysik und Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, GermanySecret communication over public channels is one of the central pillars of a modern information society. Using quantum key distribution this is achieved without relying on the hardness of mathematical problems, which might be compromised by improved algorithms or by future quantum computers. State-of-the-art quantum key distribution requires composable security against coherent attacks for a finite number of distributed quantum states as well as robustness against implementation side channels. Here we present an implementation of continuous-variable quantum key distribution satisfying these requirements. Our implementation is based on the distribution of continuous-variable Einstein–Podolsky–Rosen entangled light. It is one-sided device independent, which means the security of the generated key is independent of any memoryfree attacks on the remote detector. Since continuous-variable encoding is compatible with conventional optical communication technology, our work is a step towards practical implementations of quantum key distribution with state-of-the-art security based solely on telecom components.

Strong Einstein-Podolsky-Rosen entanglement from a single squeezed light source

Einstein-Podolsky-Rosen (EPR) entanglement is a criterion that is more demanding than just certifying entanglement. We theoretically and experimentally analyze the low-resource generation of bipartite continuous-variable entanglement, as realized by mixing a squeezed mode with a vacuum mode at a balanced beam splitter, i.e., the generation of so-called vacuum-class entanglement. We find that in order to observe EPR entanglement the total optical loss must be smaller than

Ab initio quantum-enhanced optical phase estimation using real-time feedback control

33.3

Quantum enhancement of the zero-area Sagnac interferometer topology for gravitational wave detection

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Quantum Up-Conversion of Squeezed Vacuum States from 1550 to 532 nm

. However, arbitrarily strong EPR entanglement is generally possible with this scheme. We realize continuous-wave squeezed light at

Experimental entanglement distribution by separable states

1550

Gaussian Entanglement for Quantum Key Distribution from a Single-Mode Squeezing Source

nm with up to

Efficient information reconciliation for Continuous-Variable QKD using Non-Binary Low-Density Parity-Check Codes

9.9