QuLeeYang | Lee-Yang theory of phase transitions in interacting quantum many-body systems

Summary
Over the last years, investigations of Lee-Yang zeros – complex zeros of the partition function for systems of finite size – have become an indispensable theoretical tool in equilibrium statistical physics with diverse applications, ranging from protein folding and percolation to complex networks and magnetism. In the thermodynamic limit, the Lee-Yang zeros approach the real value of the control parameter for which a phase transition occurs. Despite these developments, surprisingly little attention has so far been devoted to applications of Lee-Yang theory beyond classical equilibrium systems. One reason may be that Lee-Yang zeros (being complex values of physical quantities) for years were seen as a purely theoretical concept with little relevance to experiments. However, this view has recently been contested by several experiments, in which Lee-Yang zeros have been determined. A novel cumulant method allows for the determination of Lee-Yang zeros from measurements of fluctuating observables, thus offering a completely new perspective on phase transitions in interacting many-body systems. Here, building on this cumulant method, I propose to formulate a unifying theory of phase transitions in interacting quantum many-body systems, including space-time, dynamical, and quantum phase transitions, from the perspective of Lee-Yang zeros. I will connect this theoretical framework to large-deviation statistics, fluctuation relations, and many-body entanglement in non-classical systems. Furthermore, I will devise experimental schemes to test my predictions and, in particular, investigate quantum phase transitions in engineered quantum devices. Fulfilling these objectives will expand the field far beyond its current state-of-the-art and potentially result in major scientific breakthroughs with important implications for other research fields, such as quantum information processing and quantum thermodynamics.
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Web resources: https://cordis.europa.eu/project/id/892956
Start date: 01-04-2020
End date: 31-03-2022
Total budget - Public funding: 190 680,96 Euro - 190 680,00 Euro
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Original description

Over the last years, investigations of Lee-Yang zeros – complex zeros of the partition function for systems of finite size – have become an indispensable theoretical tool in equilibrium statistical physics with diverse applications, ranging from protein folding and percolation to complex networks and magnetism. In the thermodynamic limit, the Lee-Yang zeros approach the real value of the control parameter for which a phase transition occurs. Despite these developments, surprisingly little attention has so far been devoted to applications of Lee-Yang theory beyond classical equilibrium systems. One reason may be that Lee-Yang zeros (being complex values of physical quantities) for years were seen as a purely theoretical concept with little relevance to experiments. However, this view has recently been contested by several experiments, in which Lee-Yang zeros have been determined. A novel cumulant method allows for the determination of Lee-Yang zeros from measurements of fluctuating observables, thus offering a completely new perspective on phase transitions in interacting many-body systems. Here, building on this cumulant method, I propose to formulate a unifying theory of phase transitions in interacting quantum many-body systems, including space-time, dynamical, and quantum phase transitions, from the perspective of Lee-Yang zeros. I will connect this theoretical framework to large-deviation statistics, fluctuation relations, and many-body entanglement in non-classical systems. Furthermore, I will devise experimental schemes to test my predictions and, in particular, investigate quantum phase transitions in engineered quantum devices. Fulfilling these objectives will expand the field far beyond its current state-of-the-art and potentially result in major scientific breakthroughs with important implications for other research fields, such as quantum information processing and quantum thermodynamics.

Status

TERMINATED

Call topic

MSCA-IF-2019

Update Date

28-04-2024
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Horizon 2020
H2020-EU.1. EXCELLENT SCIENCE
H2020-EU.1.3. EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions (MSCA)
H2020-EU.1.3.2. Nurturing excellence by means of cross-border and cross-sector mobility
H2020-MSCA-IF-2019
MSCA-IF-2019