Ward-Takahashi Identity and Gauge-Invariant Response Theory for Open Quantum Systems
- URL: http://arxiv.org/abs/2602.13632v1
- Date: Sat, 14 Feb 2026 06:52:38 GMT
- Title: Ward-Takahashi Identity and Gauge-Invariant Response Theory for Open Quantum Systems
- Abstract summary: We establish the gauge-invariant response theory for open quantum systems described by Lindbladians.<n>We construct an observable which can be used to test the gauge invariance in the absence of particle-number conservation.
- Score: 7.686215365486194
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: We derive the Ward-Takahashi identity and establish the gauge-invariant response theory for open quantum systems described by Lindbladians to show that particle-number conservation is not necessary to satisfy gauge invariance. We construct an observable which can be used to test the gauge invariance in the absence of particle-number conservation. We derive the low-energy collective modes that emerge as a consequence of gauge invariance in open quantum systems, and find that two-body loss induces diffusive modes in dissipative Bardeen-Cooper-Schrieffer (BCS) superconductivity. Possible experimental situations for testing gauge invariance in open quantum systems are also discussed.
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