Commutators for functions of operators (momentum/position)

In summary, a commutator is a mathematical operation that determines the order in which two operators act on a given function. In the context of functions of operators, the commutator of momentum and position is equal to iħ and is key to understanding the uncertainty principle. Two operators can have a commutator of zero, indicating that their order does not matter. The commutator of two operators is calculated using the formula [A,B] = AB - BA. Commutators are not only used in quantum mechanics, but also in other areas of mathematics and physics. However, they play a particularly important role in quantum mechanics in describing the behavior of quantum systems and the uncertainty principle.
  • #1
Ratpigeon
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Homework Statement



show that [x,f(p_x)] = i [itex]\hbar[/itex] d/d(p_x) f(p_x)

Homework Equations



x is the position operator in the x direction, p_x is the momentum operator; i [itex]\hbar[/itex]
d/dx
[x, p_x]=xp-px

The Attempt at a Solution


I'm stuck. maybe chain rule for d/dx and d/d(p_x)...? But I don't see how I'd do it...
 
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  • #2
Never mind - I had to reqresent it as a power series, and then it was easier
 

Related to Commutators for functions of operators (momentum/position)

1. What is a commutator in the context of functions of operators?

A commutator is a mathematical operation that determines how two operators, such as momentum and position, interact with each other. In the context of functions of operators, the commutator represents the order in which the operators act on a given function.

2. How is the commutator of momentum and position related to the uncertainty principle?

The commutator of momentum and position, [p,x], is equal to iħ, where i is the imaginary unit and ħ is the reduced Planck's constant. This relationship is key to understanding the uncertainty principle, which states that the more precisely the position of a particle is known, the less precisely its momentum can be known, and vice versa.

3. Can the commutator of two operators be equal to zero?

Yes, if two operators commute, meaning their commutator is equal to zero, it means that the order in which they act on a function does not matter. This is often the case for operators that represent physical observables, such as energy and angular momentum.

4. How is the commutator of two operators calculated?

The commutator of two operators A and B is calculated using the formula [A,B] = AB - BA. This means that the commutator is equal to the difference between the product of the two operators in one order and the product in the opposite order.

5. Are commutators only used in quantum mechanics?

No, commutators are also used in other areas of mathematics and physics, such as matrix algebra and classical mechanics. However, they are particularly important in quantum mechanics as they describe the fundamental behavior of quantum systems and play a crucial role in understanding the uncertainty principle.

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