Doroncohen

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The what now?

What is an "SP formula"? Selling price? Standard package? State phase? Maury Markowitz (talk) 14:44, 25 January 2014 (UTC)

Answer1: I have been notified by email with regard to this question. Not clear to me whether it is a spam, and how should it be answered. As explained in http://en.wikipedia.org/wiki/Dephasing_rate_SP_formula the SP formula is used to calculate dephasing rate of a system the has power spectrum $P$, and is driven by noise that has power spectrum $S$. — Preceding unsigned comment added by 79.182.102.171 (talk) 15:52, 25 January 2014 (UTC)

I read the article, but I'm still not sure if this term is actually used elsewhere. I'm also wondering why this isn't part of the dephasing article? Maury Markowitz (talk) 20:19, 25 January 2014 (UTC)

Yeah, applying some google-fu it appears the term "SP formula" appears nowhere else but this article. Is this a term widely found in articles on the topic? If it's not, perhaps there is a better title, or it should simply be at the end of the general formula? Maury Markowitz (talk) 20:28, 25 January 2014 (UTC)

Answer2: In fact there is a place to consider unification of the "dephasing" page with http://en.wikipedia.org/wiki/Quantum_decoherence Note that some people make distinctions, and do not agree on terminology. As for the "SP formula" it is a very limited item that can be either separated (as it is) in order not to bother the general reader, or else it can be combined as a sub-section. In a slightly different context the latter approach has been criticized (i.e. an editor/writer had the opinion that a limited issue should be separated from the article that describes the "big" picture.)

Answer3: Regarding the term "SP formula". The integral expression is in essence the most widely used way of calculating dephasing rate. But if you go to the literature you see that: (1) It is not a named formula; (2) The integrand is not identified as the product of "S" and "P". In most publications "the formula" appears as the outcome of some system-specific formulations without paying attention to its *universality*. So you can call it if you wish "Dephasing_rate_formula", but then it is ambiguous. Also terms like "Fermi_golden-rule_based_formula_for_dephasing_rate_calculation" or "First_order_perturbation_theory_formula_for_dephasing_rate_calculation" sound not economical, and lack the precise "SP" connotation. BTW: the letters "S" and "P" are the conventional notations for power spectra.