Signals from the future

R.S. Withers, Richard W. Ralston

Real-time signal processing is important in many emerging applications in areas such as pulse-compression radar, spread-spectrum communications, and electronic warfare. The required digitally equivalent computational rate for these applications is on the order of 10/sup 2/ arithmetic operations per second and the required instantaneous bandwidths could approach 10 GHz. These exceed by nearly three orders of magnitude the capabilities projected for digital systems in the near future, and even exceed that of recently developed analog technologies such as surface-acoustic-wave (SAW) signal-processing devices. To meet anticipated future system needs, superconductive analog signal-processing components with bandwidths of 2 GHz have recently been realized, and the technology is being developed for the realization of 10-GHz bandwidths. Issues of fabrication technology and subsystem integration are examined for superconductive analog signal-processing devices.>

Jungsang Kim, Seema Somani, Y. Yamamoto

Adam Becker

Yelena Guryanova, Ralph Silva, Anthony J. Short +3 more

We present an operational and model-independent framework to investigate the concept of no-backwards-in-time signalling. We define no-backwards-in-time signalling conditions, closely related to the spatial no-signalling conditions. These allow for theoretical possibilities in which the future affects the past, nevertheless without signalling backwards in time. This is analogous to non-local but no-signalling spatial correlations. Furthermore, our results shed new light on situations with indefinite causal structure and their connection to quantum theory.

Mariam Janelidze, Lasha Janelidze

The rapid development of the digital era and the increasing demands of information technologies create a need to create more reliable, secure and efficient communication systems. In this context, quantum signals represent a technology of the future that responds to the challenges that classical signal systems can no longer cope with — for example, the highest level of information security, accuracy and transmission speed. The use of quantum entanglement, superposition and correlations makes it possible to protect and process information at the highest level. Accordingly, the implementation of quantum signals is critically important for areas such as quantum communication, secure cyberinfrastructure, high-tech sensors and quantum computing systems. The paper reviews the role of quantum signals in modern technologies and their potential in the near future. Quantum signal theory combines the principles of quantum physics, information theory and signal processing. These features provide the highest accuracy in information transmission and processing, which is especially important in the development of quantum communication, quantum radars, and quantum sensors. This paper reviews the theoretical foundations of quantum signals, basic models, and their potential applications in modern technologies.

Bob Holmes