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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2502.16258 |
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| _version_ | 1866909506110226432 |
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| author | Song, B. Q. Smith, J. D. H. Wang, J. |
| author_facet | Song, B. Q. Smith, J. D. H. Wang, J. |
| contents | The complexity of itinerant and many-body nature in Bardeen-Cooper-Schrieffer (BCS) wavefunctions has traditionally led to the use of coarse-grained order parameters for describing currents in superconductors (SC), rather than directly utilizing wavefunctions. In this work, we introduce a phase-based formula that enables the direct computation of currents from microscopic wavefunctions, accounting for correlation and particle number variations. Interestingly, the formulation draws parallels with insulators, suggesting a unified framework for understanding (intra-band) charge transport across two extremes of conductivity. A group velocity current $J_{band}{\propto}\frac{1}{\hbar}{\partial}_kE(k)$ is derived from Berry phase, independent of wave package dynamics, robust against correlation. Additionally, we identify a correlation-driven contribution, $J_{corr}$, which reveals that the pairing correlations ${\langle}c_kc_{-k}{\rangle}$ among dancing partners provide a current component beyond the velocity operator. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_16258 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Geometric origin of supercurrents in Berry phase: Formula for computing currents from wavefunctions with correlation and particle number variation Song, B. Q. Smith, J. D. H. Wang, J. Superconductivity The complexity of itinerant and many-body nature in Bardeen-Cooper-Schrieffer (BCS) wavefunctions has traditionally led to the use of coarse-grained order parameters for describing currents in superconductors (SC), rather than directly utilizing wavefunctions. In this work, we introduce a phase-based formula that enables the direct computation of currents from microscopic wavefunctions, accounting for correlation and particle number variations. Interestingly, the formulation draws parallels with insulators, suggesting a unified framework for understanding (intra-band) charge transport across two extremes of conductivity. A group velocity current $J_{band}{\propto}\frac{1}{\hbar}{\partial}_kE(k)$ is derived from Berry phase, independent of wave package dynamics, robust against correlation. Additionally, we identify a correlation-driven contribution, $J_{corr}$, which reveals that the pairing correlations ${\langle}c_kc_{-k}{\rangle}$ among dancing partners provide a current component beyond the velocity operator. |
| title | Geometric origin of supercurrents in Berry phase: Formula for computing currents from wavefunctions with correlation and particle number variation |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2502.16258 |