Metastability, Memory, and Dissipation in Open Quantum Systems

01/08/2026 to 31/07/2028

Open quantum systems are inherently influenced by their environment, causing dissipation and decoherence, often regarded as detrimental to coherent quantum control. However, recent studies have revealed that such effects can be exploited as valuable resources. Engineered dissipation enables, for example, the preparation of nontrivial quantum states, like coherent cat states and highly entangled states relevant for quantum technologies. Quantum mechanics also offers new opportunities for data processing and computation. In particular, the quantum effects may be beneficial in the context of machine learning. This raises a fundamental question: can quantum phenomena be exploited to boost neural network performance? Notably, this question is closely related to the study of open quantum many-body systems - a topic extensively explored by the host group [PRA 111, 062405 (2025)].
This proposal investigates two complementary aspects of open quantum systems, which will be simultaneously pursued during the two-year duration of the project: (I) utilization of open quantum systems as associative memories, e.g. [New Journal of Physics 24, 033012 (2022)], which strongly depends on the formation of long-lived metastable states. Recently, theoretical studies, including several by the host group, have demonstrated the property of multi-mode spin-boson model to store and retrieve memory patterns through its dissipative dynamics. Such properties lead to ergodicity breaking in open quantum systems. (II) the suppression of these metastable modes for accelerated relaxation to the nontrivial states, which are of interest in quantum metrology.