Zenith Grant Awardee
Otfried Gühne
University of Siegen
Co-Investigators
Adan Cabello, University of Seville; Jan-Åke Larsson, University of Linköping
Project Title
The nature of information in sequential quantum measurements
Project Summary
Quantum physics is known to contradict the classical world view and this contradiction becomes apparent in several phenomena. A famous quantum effect is entanglement, which means that the correlations between two or more distant particles can be stronger than in the classical world. There are, however, also quantum phenomena arising if a sequence of measurements on a single particle is made. The results of such a sequence of quantum measurements can not be explained by using classical physics only and recent experiments with ions or light particles have observed such effects. In our project we study information in sequences of quantum measurements. This includes questions as: What is the information determining the future measurement results? What is the complexity of the sequence of the measurement results? How can we describe the randomness in such a sequence? We will also investigate the historical development of research at the border between quantum and classical physics by conducting video interviews with some of the founding fathers of this field. This helps to understand the subject, since the study of information in quantum physics was one of the driving ideas behind many works in the past.
Technical Abstract
Several intuitive assumptions that are taken for granted in classical physics turned out not to hold in the quantum world. The most famous result is Bell\'s theorem that states the incompatibility of local realism with the predictions of quantum mechanics for measurements on distant particles. There are related results, such as the Kochen-Specker theorem or Leggett-Garg inequalities that prove a contradiction between quantum mechanics and noncontextuality or macrorealism. These theorems rely on sequences of measurements made on a single quantum system, rather than measurements on distant particles. In this project, we investigate the nature of information in sequential quantum measurements. This includes questions as: What is the information determining the future measurement results? What is the memory that can be accessed with sequential measurements? Can the predictions of quantum mechanics for sequential measurements be derived from information-theoretic principles? For answering these questions, we will collaborate with researchers on classical complexity. Moreover, we will also shed light on the historical genesis of the Kochen-Specker theorem and related results, since speculations about the nature of information in quantum measurements were already a key motivation for the formulation of the theorem.
QSpace Latest
PressRelease: Shining a light on the roots of plant “intelligence”
All living organisms emit a low level of light radiation, but the origin and function of these ‘biophotons’ are not yet fully understood. An international team of physicists, funded by the Foundational Questions Institute, FQxI, has proposed a new approach for investigating this phenomenon based on statistical analyses of this emission. Their aim is to test whether biophotons can play a role in the transport of information within and between living organisms, and whether monitoring biophotons could contribute to the development of medical techniques for the early diagnosis of various diseases. Their analyses of the measurements of the faint glow emitted by lentil seeds support models for the emergence of a kind of plant ‘intelligence,’ in which the biophotonic emission carries information and may thus be used by plants as a means to communicate. The team reported this and reviewed the history of biophotons in an article in the journal Applied Sciences in June 2024.