# Circuit configurations which can/cannot show super-radiant phase transitions

## TL;DR

This paper investigates various superconducting circuit configurations to determine whether they can exhibit super-radiant phase transitions in thermal equilibrium, confirming the absence in some cases and leaving others unresolved.

## Contribution

It provides a systematic analysis of circuit configurations regarding super-radiant phase transitions, extending no-go theorems from atomic systems to superconducting circuits.

## Key findings

- Confirmed absence of SRPTs in certain configurations
- Identified configurations where SRPTs cannot be ruled out
- Extended no-go theorems to superconducting circuits

## Abstract

Several superconducting circuit configurations are examined on the existence of super-radiant phase transitions (SRPTs) in thermal equilibrium. For some configurations consisting of artificial atoms, whose circuit diagrams are however not specified, and an LC resonator or a transmission line, we confirm the absence of SRPTs in the thermal equilibrium following the similar analysis as the no-go theorem for atomic systems. We also show some other configurations where the absence of SRPTs cannot be confirmed.