dorsal/arxiv
View SchemaNew Bardeen-Cooper-Schrieffer-type theory at finite temperature with particle-number conservation
| Authors | H. Nakada, K. Tanabe |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0603113 |
| URL | https://arxiv.org/abs/quant-ph/0603113 |
| DOI | 10.1103/PhysRevC.74.061301 |
| Journal | Phys.Rev. C74 (2006) 061301 |
Abstract
We formulate a new Bardeen-Cooper-Schrieffer (BCS)-type theory at finite temperature, by deriving a set of variational equations of the free energy after the particle-number projection. With its broad applicability, this theory can be a useful tool for investigating the pairing phase transition in finite systems with the particle-number conservation. This theory provides effects of the symmetry-restoring fluctuation (SRF) for the pairing phenomena in finite fermionic systems, distinctively from those of additional quantum fluctuations. It is shown by numerical calculations that the phase transition is compatible with the conservation in this theory, and that the SRF shifts up the critical temperature ($T^\mathrm{cr}$). This shift of $T^\mathrm{cr}$ occurs due to reduction of degrees-of-freedom in canonical ensembles, and decreases only slowly as the particle-number increases (or as the level spacing narrows), in contrast to the conventional BCS theory.
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"abstract": "We formulate a new Bardeen-Cooper-Schrieffer (BCS)-type theory at finite\ntemperature, by deriving a set of variational equations of the free energy\nafter the particle-number projection. With its broad applicability, this theory\ncan be a useful tool for investigating the pairing phase transition in finite\nsystems with the particle-number conservation. This theory provides effects of\nthe symmetry-restoring fluctuation (SRF) for the pairing phenomena in finite\nfermionic systems, distinctively from those of additional quantum fluctuations.\nIt is shown by numerical calculations that the phase transition is compatible\nwith the conservation in this theory, and that the SRF shifts up the critical\ntemperature ($T^\\mathrm{cr}$). This shift of $T^\\mathrm{cr}$ occurs due to\nreduction of degrees-of-freedom in canonical ensembles, and decreases only\nslowly as the particle-number increases (or as the level spacing narrows), in\ncontrast to the conventional BCS theory.",
"arxiv_id": "quant-ph/0603113",
"authors": [
"H. Nakada",
"K. Tanabe"
],
"categories": [
"quant-ph",
"cond-mat.supr-con",
"nucl-th"
],
"doi": "10.1103/PhysRevC.74.061301",
"journal_ref": "Phys.Rev. C74 (2006) 061301",
"title": "New Bardeen-Cooper-Schrieffer-type theory at finite temperature with particle-number conservation",
"url": "https://arxiv.org/abs/quant-ph/0603113"
},
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