References: continuum approximation of discrete sums?

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Discussion Overview

The discussion revolves around the accuracy of the continuum approximation of discrete sums, particularly in the context of mathematical references and applications in quantum optics. Participants seek to explore the theoretical underpinnings and practical implications of this approximation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant requests additional references on the accuracy of the continuum approximation to discrete sums, highlighting a specific mathematical example of summation to integral.
  • Another participant shares a link to Terry Tao's discussion on the Euler-Maclaurin formula, which is relevant to the topic.
  • A participant questions the relevance of posting in the Quantum subforum, suggesting a need for a less abstract analysis of the approximation's error in practical applications.
  • Concerns are raised about the complexity of related mathematical concepts, such as zeta and Bernoulli functions, indicating a desire for more accessible explanations.
  • A participant shares a specific reference to a paper discussing Fermi's golden rule and its derivation, noting its relevance to the continuum approximation.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the best references or methods for analyzing the continuum approximation, and multiple viewpoints regarding its application and mathematical complexity remain present.

Contextual Notes

Participants express uncertainty regarding the mathematical rigor required for understanding the continuum approximation and its implications in physical models, particularly in quantum optics.

yucheng
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Is there more references for how accurate is the continuum approximation to discrete sums? Perhaps more mathematical.

What I've found:
https://lonitch.github.io/Sum-to-Int/
https://arxiv.org/pdf/2102.10941.pdf

Some examples are:
Sum to integral
$$\sum_{\mathbf{k}} \to 2 \left ( \frac{L}{2 \pi} \right ) \int d^3k$$

Density of oscillator modes etc
 
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Here is Terry Tao discussing the Euler-Maclaurin formula mentioned in your arxiv link: link.

EDIT: Also, is there a reason you posted this in the Quantum subforum?
 
Haborix said:
EDIT: Also, is there a reason you posted this in the Quantum subforum?
Thanks!

Yes it appears in many places in Quantum optics, so I was hoping that there is a less mathematically abstract analysis, especially that of the error in the approximation (for instance, applying it to a model physical system, comparing the exact sum vs continuum approximation), whether it causes deviations from experimental results.....

P.S. the zeta functions, bernoulli functions makes me want to cry, but if that's what's needed, then I'll have to slowly crawl my way there...
 
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I did find one! Serendipity!

Fermi's golden rule: its derivation and breakdown by an ideal model by J. M. Zhang, Y. Liu

Search in document:
in replacing the summation by an integral, the sampling step-length
https://arxiv.org/pdf/1604.06916.pdf
 
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