I am doing a measurement in a system S with the apparatus A, in an

In summary, the conversation discusses the measurement of a quantum system S with an apparatus A in an environment E. The state of the apparatus will depend on its interaction with the system and after the decoherence time, it will have a density operator that increases its entropy. However, during the collapse of the wavefunction, the entropy of both the system and the apparatus decreases. This raises the question of why entropy is said to increase in a measurement, and it is suggested that this may be due to the initial state of the system and apparatus being a superposition of different states.
  • #1
StarsRuler
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I am doing a measurement in a system S with the apparatus A, in an entorn E. If the system is at [STRIKE]t0[/STRIKE] in Sithe measurement of the apparatus will be, after the decoherence time
 
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  • #2


Is that a question? The state of the apparatus will depend on the interaction with the system.
What is "entorn"? Google suggest "environment", translated from catalan.
 
  • #3


I don´t understand why the collapse of the wavefunction and the measure increase entropy. I start with a quantum system S and an aparattus A. The initial state of [ S+A ] is [(c_1|s_1>+c_2|s_2>+...)|a_0> ] and after the decoherence implies than apparatus end with a density operator [ p_1|1><a_1|+p_2|a_2><a_2|] where [p_n=|c_n|^2] ...His entropy goes up by shannon entropy to [-(p_1 ln (p_1)+p_2 ln (p_2)+...] that is [S>0] , in the premeasurement. But when collapse occurs , the final state of apparatus is [|a_n><a_n|] , for a random [n] , then it has entropy [S=0] . The entropy goes down and the same occurs to the system. Then why it is said that entropy goes up in a measurement?
 

FAQ: I am doing a measurement in a system S with the apparatus A, in an

What is the purpose of conducting a measurement in a system with the apparatus A?

The purpose of conducting a measurement in a system with the apparatus A is to gather data and obtain precise and accurate measurements of a particular variable or phenomenon within the system. This information can then be used to understand and analyze the behavior of the system and make informed conclusions or predictions.

How does the apparatus A affect the measurements in system S?

The apparatus A is designed and calibrated to minimize any external influences and accurately capture the desired measurements within system S. It is important to carefully select and properly use the apparatus A to ensure that the measurements are not distorted or biased in any way.

What are some common sources of error in measurements taken with the apparatus A in system S?

Some common sources of error in measurements taken with the apparatus A in system S include environmental factors such as temperature, humidity, and vibration, as well as human error in the setup or reading of the apparatus. It is important to identify and minimize these sources of error to ensure the accuracy of the measurements.

How do you ensure the reliability and validity of the measurements taken in system S with the apparatus A?

To ensure the reliability and validity of the measurements, it is important to follow standardized procedures and protocols for conducting the measurements. This includes properly calibrating and maintaining the apparatus A, controlling for potential sources of error, and repeating the measurements multiple times to ensure consistency and accuracy.

What are some potential applications of the measurements taken in system S with the apparatus A?

The measurements taken in system S with the apparatus A can be used in a variety of applications, such as scientific research, engineering design, and quality control in manufacturing. They can also provide valuable insights and data for understanding and predicting the behavior of complex systems and processes in various fields.

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