Quantum Many-Body Physics in Open Systems: Measurement and Strong Correlations

This book studies the fundamental aspects of many-body physics in quantum systems open to an external world. Recent remarkable developments in the observation and manipulation of quantum matter at the single-quantum level point to a new research area of open many-body systems, where interactions with an external observer and the environment play a major role.

The first part of the book elucidates the influence of measurement backaction from an external observer, revealing new types of quantum critical phenomena and out-of-equilibrium dynamics beyond the conventional paradigm of closed systems. In turn, the second part develops a powerful theoretical approach to study the in- and out-of-equilibrium physics of an open quantum system strongly correlated with an external environment, where the entanglement between the system and the environment plays an essential role. The results obtained here offer essential theoretical results for understanding the many-body physics of quantum systems open to an external world, and can be applied to experimental systems in atomic, molecular and optical physics, quantum information science and condensed matter physics.

Chap. 1 Motivation and Outline

Part I Quantum Many-Body Systems under Continuous Observation
Chap. 2 Continuous Observation of Quantum Systems
Chap. 3 Quantum Critical Phenomena
Chap. 4 Out-of-Equilibrium Quantum Dynamics

Part II Quantum Systems Strongly Correlated with Environment
Chap. 5 Quantum Spin in an Environment
Chap. 6 Quantum Particle in a Magnetic Environment
Chap.7 Conclusions and Outlook

Appendices

Yuto Ashida is an Assistant Professor at the Department of Applied Physics, the University of Tokyo. His work is concerned with an interdisciplinary field of condensed matter physics, AMO physics, and statistical physics. He received his Ph.D. in science from the University of Tokyo in March 2019. Since August 2016, he has intermittently visited Harvard University as a visiting researcher. He received the President's award from the University of Tokyo and Ikushi Prize from the Japan Society for the Promotion of Science (JSPS) in 2019.