References: continuum approximation of discrete sums?

In summary, there are multiple references available for the accuracy of the continuum approximation to discrete sums in quantum optics, such as the Euler-Maclaurin formula and Fermi's golden rule. However, more mathematical analysis is needed to fully understand the error in the approximation and its impact on experimental results.
  • #1
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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  • #2
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?
 
  • #3
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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  • #4
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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1. What is the continuum approximation of discrete sums?

The continuum approximation of discrete sums is a mathematical technique used to approximate a discrete sum with a continuous integral. It is based on the idea that as the number of terms in a sum increases, the difference between the discrete sum and the continuous integral becomes smaller.

2. Why is the continuum approximation of discrete sums useful?

This technique is useful because it allows for easier calculation of sums that would otherwise be difficult to solve. It also provides a more accurate approximation of the sum compared to using a finite number of terms.

3. What are the limitations of the continuum approximation of discrete sums?

The continuum approximation of discrete sums is not always accurate, especially when dealing with rapidly changing functions or when the number of terms in the sum is small. It also assumes that the function being summed is continuous, which may not always be the case.

4. How is the continuum approximation of discrete sums used in real-world applications?

This technique is commonly used in physics and engineering to solve problems involving continuous systems, such as fluid dynamics and electromagnetism. It is also used in statistics and economics to approximate integrals and calculate probabilities.

5. Are there any alternative methods to the continuum approximation of discrete sums?

Yes, there are other methods such as the Euler-Maclaurin formula and the trapezoidal rule, which can also be used to approximate discrete sums. However, the continuum approximation is often preferred due to its simplicity and accuracy in many cases.

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