Practical cryptographic strategies in the post-quantum era

We review new frontiers in information security technologies in communications and distributed storage technologies with the use of classical, quantum, hybrid classical-quantum, and post-quantum cryptography. We analyze the current state-of-the-art, critical characteristics, development trends, and limitations of these techniques for application in enterprise information protection systems. An approach concerning the selection of practical encryption technologies for enterprises with branched communication networks is introduced.Comment: 5 pages, 2 figures; review pape

Synthesis of the Einstein-Podolsky-Rosen entanglement in a sequence of two single-mode squeezers

Synthesis of the Einstein-Podolsky-Rosen entangled state --- the primary entangled resource in continuous-variable quantum-optical information processing --- is a technological challenge of great importance. Here we propose and implement a new scheme of generating this state. Two nonlinear optical crystals, positioned back-to-back in the waist of a pump beam, function as single-pass degenerate optical parametric amplifiers and produce single-mode squeezed vacuum states in orthogonal polarization modes, but in the same spatiotemporal mode. A subsequent pair of waveplates acts as a beam splitter, entangling the two polarization modes to generate the Einstein-Podolsky-Rosen state. This technique takes advantage of the strong nonlinearity associated with type-I phase-matching configuration while at the same time eliminating the need for actively stabilizing the optical phase between the two squeezers, which typically arises if these squeezers are spatially separated. We demonstrate our method in an experiment, preparing a 1.4 dB two-mode squeezed state and characterizing it via two-mode homodyne tomography.Comment: 4 pages, 3 figure

Undoing the effect of loss on quantum entanglement

Entanglement distillation is a process via which the strength and purity of quantum entanglement can be increased probabilistically. It is a key step in many quantum communication and computation protocols. In particular, entanglement distillation is a necessary component of the quantum repeater, a device which counters the degradation of entanglement that inevitably occurs due to losses in a communication line. Here we report an experiment on distilling the Einstein-Podolsky-Rosen (EPR) state of light, the workhorse of continuous-variable entanglement, using the technique of noiseless amplification. In contrast to previous implementations, the entanglement enhancement factor achievable by our technique is not fundamentally limited and permits recovering an EPR state with a macroscopic level of entanglement no matter how low the initial entanglement or how high the loss may be. In particular, we recover the original level of entanglement after one of the EPR modes has passed through a channel with a loss factor of 20. The level of entanglement in our distilled state is higher than that achievable by direct transmission of any state through a similar loss channel. This is a key bench-marking step towards the realization of a practical continuous-variable quantum repeater and other CV quantum protocols.Comment: 8 pages, 5 figure

Investment Policy in the Conditions of the Knowledge Economy: New Tools and Valuable Bases

The article is devoted to research of specific goals, objectives and content of the state investment policy in the conditions of formation and development of the knowledge-based economy. The authors analyze key features of the new economy, its influence to and interrelation with political, social and cultural spheres of society. Particular emphasis is placed on the need to develop a consensus strategy of the investment policy, the necessity of its inclusion in the broader context of national economic policy, taking into account a broad range of challenges and risks faced by modern society. The investment policy must be viewed in close connection with the rebranding of the area, its social, geographical and cultural characteristics. As key tools to solve this problem in the article describes modern network technologies: crowdsourcing, benchmarking, marketing territory, etc

Quantum-secured blockchain

Blockchain is a distributed database which is cryptographically protected against malicious modifications. While promising for a wide range of applications, current blockchain platforms rely on digital signatures, which are vulnerable to attacks by means of quantum computers. The same, albeit to a lesser extent, applies to cryptographic hash functions that are used in preparing new blocks, so parties with access to quantum computation would have unfair advantage in procuring mining rewards. Here we propose a possible solution to the quantum era blockchain challenge and report an experimental realization of a quantum-safe blockchain platform that utilizes quantum key distribution across an urban fiber network for information-theoretically secure authentication. These results address important questions about realizability and scalability of quantum-safe blockchains for commercial and governmental applications.Comment: 7 pages, 2 figures; published versio