Zwiebach Page 194 Q11.3: Understanding "Viewing" a Time-Dependent Heisenberg Op.

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In summary, a time-dependent Heisenberg operator is a way to represent the change of an observable quantity in quantum mechanics over time. "Viewing" this operator involves calculating its expected value in a given state, rather than physically measuring it. Understanding how to "view" this operator is crucial for predicting the behavior of a system and understanding fundamental principles of quantum mechanics. The expected value of a time-dependent Heisenberg operator is calculated using the inner product of the state vector and the operator. This value can change over time as the state of the system changes, reflecting the probabilistic nature of quantum mechanics.
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ehrenfest
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Homework Statement


I am confused about Quick Calculation 11.3. What does he mean "by viewing x_0^I as the explicitly time-dependent Heisenberg operator defined by (11.38)"?

Specifically, what does "viewing" mean?


Homework Equations





The Attempt at a Solution

 
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This one is not clear to me either. However, what I did was assume that [itex]x_0^I[/itex] does have explicit time dependence by rewriting equation (11.38) on page 193 as

[tex]x_0^I(\tau) = x^I(\tau) - \frac{p^I}{m^2}\tau[/tex]

and then showing that the derivative w.r.t. [itex]\tau[/itex] is zero. It's not hard enough to justify a QC though.
 

1. What is a time-dependent Heisenberg operator?

A time-dependent Heisenberg operator is a mathematical representation of an observable quantity in quantum mechanics that changes over time. It is used to describe how the state of a system evolves as time progresses.

2. How does "viewing" a time-dependent Heisenberg operator differ from measuring it?

In quantum mechanics, the act of "viewing" or observing a time-dependent Heisenberg operator does not necessarily involve physically measuring it. Instead, it refers to the process of calculating the expected value of the operator in a given state of the system.

3. What is the significance of understanding "viewing" a time-dependent Heisenberg operator?

Understanding how to "view" a time-dependent Heisenberg operator is crucial in quantum mechanics as it allows us to make predictions about the behavior of a system over time. It also helps us to better understand the fundamental principles of quantum mechanics, such as the uncertainty principle.

4. How is the expected value of a time-dependent Heisenberg operator calculated?

The expected value of a time-dependent Heisenberg operator is calculated by taking the inner product of the state vector and the operator, and then multiplying it by the conjugate transpose of the state vector. This can be represented mathematically as <ψ|A(t)|ψ>, where ψ is the state vector and A(t) is the time-dependent Heisenberg operator.

5. Can the expected value of a time-dependent Heisenberg operator change over time?

Yes, the expected value of a time-dependent Heisenberg operator can change over time as the state of the system changes. This reflects the probabilistic nature of quantum mechanics, where the expected value of an observable quantity can vary depending on the state of the system.

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