Linear operators and a change of basis

In summary, the conversation discusses the operator Omega and its properties, including its Hermiticity and its representation in different bases. The participants also discuss the operator U and its unitarity, and the difficulty in writing it out in terms of kets and bras. The reason for Omega being non-Hermitian is not clear, and there is a need for clarification.
  • #1
wakko101
68
0
So...I've got an operator.

Omega = (i*h-bar)/sqrt(2)[ |2><1| + |3><2| - |1><2| - |2><3| ]

Part a asks if this is Hermitian, and my answer, unless I'm missing something, is no. Because the second part in square brackets is |1><2| + |2><3| - |2><1| - |2><3| which is not the same as Omega.

The second part asks to construct the matrix Omega(ij) = <i|Omega|j> that represents this operator in the basis {|1>, |2>, |3>}. I figured it out to be
0 1 0
1 0 1 all multiplied by that funky complex factor at the beginning.
0 1 0

Or so I think.

The third part is where it gets tricky. It gives a new basis {|1'>, |2'>, |3'>} that's somewhat complicated looking and written in terms of the original basis vectors. It asks to write out the operator

U = (from i=1 to 3) SUM(|i'><i|)

in terms of the kets {|1>, |2>, |3>} and bras {<1|, <2|, <3|}. And it asks if the operator is unitary. My problem is this...how do I go about writing out this operator?
 
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  • #2
I don't think your reason for it being non-Hermitian makes sense. The part in brackets can't be the same as Omega because there's a factor out the front, could you clarify what you meant? I would say that Omega is not because <2|O(1)> does not equal <O(2)|1>.
 

Related to Linear operators and a change of basis

What is a linear operator?

A linear operator is a function that maps one vector space to another, and preserves the operations of addition and scalar multiplication. In other words, it is a mathematical tool used to transform vectors from one coordinate system to another in a way that maintains their linear properties.

What is the role of a change of basis in linear operators?

A change of basis is a fundamental concept in linear algebra that allows us to represent the same vector in different coordinate systems. In the context of linear operators, a change of basis allows us to apply the same transformation to a vector expressed in different coordinate systems, making it a powerful tool for solving problems in different contexts.

How do I determine the matrix representation of a linear operator?

To determine the matrix representation of a linear operator, you can represent the operator as a transformation matrix and then apply the change of basis formula to transform it into the desired coordinate system. Alternatively, you can use the eigenvalues and eigenvectors of the operator to construct the matrix representation.

What is the relationship between eigenvalues and eigenvectors in linear operators?

Eigenvalues and eigenvectors play a crucial role in understanding linear operators. An eigenvector is a vector that is transformed only by a scalar factor when operated on by a linear operator. The corresponding scalar factor is known as the eigenvalue. Together, they provide important information about the behavior of a linear operator and can be used to simplify calculations and solve problems.

How do I apply linear operators to solve real-world problems?

Linear operators have a wide range of applications in various scientific fields, such as physics, engineering, and economics. They can be used to model physical systems, analyze data, and make predictions. By understanding the properties and behavior of linear operators, scientists can use them to solve real-world problems and make important discoveries.

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