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Uniqueness of the Phase Transition in Many-Dipole Cavity Quantum Electrodynamical Systems
1Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
Physical Review Letters
|October 16, 2020
Summary
A superradiant phase transition in light-matter systems is possible, resolving conflicting theorems. Gauge choice determines if the transition is superradiant, clarified by macroscopic polarization in cavity QED systems.
Area of Science:
- Quantum optics
- Condensed matter physics
- Cavity Quantum Electrodynamics (QED)
Background:
- Superradiant phase transitions in light-matter systems are debated due to conflicting theoretical results.
- Existing no-go and counter no-go theorems present paradoxes regarding the occurrence of superradiance.
Purpose of the Study:
- To resolve the long-standing paradoxes surrounding superradiant phase transitions.
- To demonstrate the unambiguous occurrence of a unique phase transition in many-dipole cavity QED systems.
- To elucidate the role of gauge choice in defining superradiance.
Main Methods:
- Utilized an arbitrary-gauge approach for theoretical analysis.
- Investigated archetypal many-dipole cavity Quantum Electrodynamics (QED) systems.
- Focused on macroscopic, gauge-invariant polarization as a key observable.
Main Results:
- A unique phase transition is shown to occur in the studied systems.
- The transition unambiguously manifests via a macroscopic gauge-invariant polarization.
- Gauge choice dictates the inclusion of polarization in the quantum subsystem, affecting the superradiant classification.
Conclusions:
- The paradox of no-go and counter no-go theorems for superradiance is resolved.
- Superradiance is shown to depend on the definition of radiation and the gauge-dependent inclusion of polarization.
- A clear pathway for observing superradiant phase transitions in cavity QED systems is established.
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