U(1) and SU(2) quantum dissipative systems: the Caldeira-Leggett versus Ambegaokar-Eckern-Schön approaches
Shnirman A., Saha A., Burmistrov I.S., Kiselev M.N., Altland A., Gefen Yu.

Received: August 4, 2015

DOI: 10.7868/S0044451016030172

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There are two paradigmatic frameworks for treating quantum systems coupled to a dissipative environment: the Caldeira-Leggett and Ambegaokar-Eckern-Schön approaches. Here, we recall the differences between them and explain the consequences of applying each to a zero-dimensional spin (having an SU(2) symmetry) in a dissipative environment (a dissipative quantum dot near or beyond the Stoner instability point).