In the delayed-choice quantum eraser, why is a stepper motor used?

In summary, a stepper motor is used in the delayed-choice quantum eraser to precisely control the position and timing of optical elements, enabling the manipulation of photon paths and the subsequent measurement of quantum interference effects. This control is crucial for demonstrating the principles of quantum mechanics, particularly the wave-particle duality and the impact of measurement on quantum states.
  • #1
murtazashab
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It appears to misunderstand the notion of the detectors D3, D4 providing path information and affecting the results D0.

My question is: When there is no path information being provided, why does the experiment still call for moving D0?

I understand that by moving D0 we can modify the arrival time of the idler photon.

I don't understand, why when there is no path information being provided at D3,D4 do we need to still move D0 in order to obtain an interference pattern.

"During an experiment, detector D0 is scanned along its x axis, its motions controlled by a step motor. A plot of "signal" photon counts detected by D0 versus x can be examined to discover whether the cumulative signal forms an interference pattern. "

Source: https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser

Why doesn't an interference pattern occur at a stationary D0, when there is no path information being provided at D3,D4?
 
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  • #2
murtazashab said:
Why doesn't an interference pattern occur at a stationary D0?
If the detector remains at a single point then all we get is the intensity at that point. An interference pattern is different intensities at different points, so we need to measure at multiple points.
 
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  • #3
@Nugatory thanks for response let me try this. ... Appreciated your efforts...
 
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FAQ: In the delayed-choice quantum eraser, why is a stepper motor used?

Why is a stepper motor used in the delayed-choice quantum eraser experiment?

A stepper motor is used in the delayed-choice quantum eraser experiment to precisely control the position of optical components, such as mirrors or beam splitters. This precision is crucial for ensuring that the experimental setup can be accurately adjusted and maintained, which is necessary for obtaining reliable and reproducible results.

How does the stepper motor contribute to the accuracy of the experiment?

The stepper motor contributes to the accuracy of the experiment by allowing for fine adjustments in the positioning of optical components. This high level of control helps in aligning the optical paths correctly, ensuring that the interference patterns or other quantum effects can be observed as intended. Inaccurate positioning could lead to erroneous results or misinterpretations of the quantum phenomena being studied.

Is the stepper motor essential for the delayed-choice aspect of the experiment?

While the stepper motor itself is not directly related to the delayed-choice aspect of the experiment, it plays a crucial role in setting up and maintaining the precise conditions needed for the experiment. The delayed-choice quantum eraser relies on the accurate timing and positioning of various components, and the stepper motor helps achieve this precision.

Can other types of motors be used instead of a stepper motor in this experiment?

Other types of motors can be used, but stepper motors are preferred due to their ability to make precise, incremental movements. This level of control is particularly important in quantum experiments where even slight deviations can significantly affect the results. Stepper motors also provide repeatability and stability, which are essential for conducting rigorous scientific experiments.

What are the advantages of using a stepper motor over manual adjustments?

Using a stepper motor over manual adjustments offers several advantages, including higher precision, repeatability, and the ability to automate the positioning process. Manual adjustments can introduce human error and lack the fine control needed for delicate quantum experiments. Stepper motors can be programmed to move to exact positions and can be controlled remotely, making the experimental setup more efficient and reliable.

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