Encoding secret information in measurement settings

Secure communication protocols are often formulated in a paradigm where the message is encoded in measurement outcomes. In this work we propose a rather unexplored framework in which the message is encoded in measurement settings rather than in their outcomes. In particular, we study two different variants of such secure communication protocols in which the message alphabet corresponds to measurement settings of mutually unbiased bases.Comment: 4 page

Optimal Distributed Controller Synthesis for Chain Structures: Applications to Vehicle Formations

We consider optimal distributed controller synthesis for an interconnected system subject to communication constraints, in linear quadratic settings. Motivated by the problem of finite heavy duty vehicle platooning, we study systems composed of interconnected subsystems over a chain graph. By decomposing the system into orthogonal modes, the cost function can be separated into individual components. Thereby, derivation of the optimal controllers in state-space follows immediately. The optimal controllers are evaluated under the practical setting of heavy duty vehicle platooning with communication constraints. It is shown that the performance can be significantly improved by adding a few communication links. The results show that the proposed optimal distributed controller performs almost as well as the centralized linear quadratic Gaussian controller and outperforms a suboptimal controller in terms of control input. Furthermore, the control input energy can be reduced significantly with the proposed controller compared to the suboptimal controller, depending on the vehicle position in the platoon. Thus, the importance of considering preceding vehicles as well as the following vehicles in a platoon for fuel optimality is concluded

Estimation of Output Channel Noise for Continuous Variable Quantum Key Distribution

Estimation of channel parameters is important for extending the range and increasing the key rate of continuous variable quantum key distribution protocols. We propose a new estimator for the channel noise parameter based on the method of moments. The method of moments finds an estimator from the moments of the output distribution of the protocol. This estimator has the advantage of being able to use all of the states shared between Alice and Bob. Other estimators are limited to a smaller publicly revealed subset of the states. The proposed estimator has a lower variance for high loss channel than what has previously been proposed. We show that the method of moments estimator increases the key rate by up to an order of magnitude at the maximum transmission of the protocol.Comment: 5 pages, 3 figure

Maximizing device-independent randomness from a Bell experiment by optimizing the measurement settings

The rates at which a user can generate device-independent quantum random numbers from a Bell-type experiment depend on the measurements that he performs. By numerically optimising over these measurements, we present lower bounds on the randomness generation rates for a family of two-qubit states composed from a mixture of partially entangled states and the completely mixed state. We also report on the randomness generation rates from a tomographic measurement. Interestingly in this case, the randomness generation rates are not monotonic functions of entanglement

An Evaluation of Archaeological Sites in the Vicinity of Floodwater Retarding Structure No. 2 Dry Comal Creek, Comal County, Texas

During September and October of 1977, 10 days of limited testing and survey were carried out by personnel from the Center for Archaeological Research (CAR), The University of Texas at San Antonio, under the supervision of Dr. Thomas R. Hester. The work was conducted under the terms of Purchase Order No. 40-7442-1501 issued by the United States Department of Agriculture (USDA) Soil Conservation Service (SCS). The sites tested were in the area to be modified by the construction of Floodwater Retarding Structure No.2 located on Dry Comal Creek in Comal County, south central Texas (Fig. 1). The testing was the second phase of investigation, following a survey in 1974, in the areas to be modified by the construction of Floodwater Retarding Structures 1 and 2 (Hester, Bass and Kelly 1975). In 1975, limited testing and additional survey were undertaken in the area affected by Structure No.1 (Kelly and Hester 1975a; 1975b). The field work done in 1977, the subject of this report, was supervised by Cristi Assad, aided by Waynne Cox and Thomas Miller. All field notes, maps and artifacts are on file at the Center for Archaeological Research

The multilateral agency : the approach, the perspective and the means

Cover titleLecture by Dr. Assad Kotaite, President of the Council of the International Civil Aviation Organization (ICAO), at the Massachusetts Institute of Technology (MIT) (Cambridge, Massachusetts - 14 July 1981)"--p. [1]July 198