Finite Temperature Density Matrix Calculation

In summary, the problem requires finding the finite temperature density of a given matrix. The first step involves finding the eigenvectors and eigenvalues of the matrix. Once the matrix is obtained, the density operator should have a unit trace, and the eigenvectors should be normalized. The final result should have a fraction involving the sum of the exponential terms and the eigenvectors.
  • #1
bowlbase
146
2

Homework Statement


Consider the Hamiltonian ##H=\begin{bmatrix} 0& \frac{-iw}{2}\\ \frac{iw}{2} & 0 \end{bmatrix}##
Write the finite temperature density of the matrix ##\rho(T)##

Homework Equations


##\beta=\frac{1}{kT}##

The Attempt at a Solution


The initial part of the problem had me find the eigenvectors and eigenvalues. I got ##\lambda=\pm\frac{w}{2}## and eigenvectors ##v_1=(-i, 1)## and ##v_1=(i, 1)##

Not quite sure what to do with it from here. I know that ##\rho=e^{-\beta E_1} | \psi_1 \rangle \langle \psi_1 |+e^{-\beta E_2} | \psi_2 \rangle \langle \psi_2 |##

I think I remember that the eigenvalues are suppose to be ##E_{1,2}##. But I don't know what ##\psi_{1,2}## are suppose to be.

Further, my notes show that once I have the matrix I should have a fraction that looks something like ##\frac{1}{2z}## where ##z## is the sum ##z=e^{-\beta E_1}+e^{-\beta E_2}##
 
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  • #2
[itex] |\psi_1 \rangle [/itex] and [itex] |\psi_2 \rangle [/itex] are normalized eigenvectors of the Hamiltonian. You have the eigenvectors, you just need to normalize them.
About the factor of [itex] \frac{1}{2z} [/itex], the density operator [itex] \rho [/itex] should have unit trace. But I don't think there should be a factor [itex] \frac 1 2 [/itex] there!
 
  • #3
I got it figured it out. I just couldn't find it in my textbook. Turns out in was in recommended reading I guess. Thanks for the help though.
 

1. What is a Finite Temperature matrix?

A Finite Temperature matrix is a mathematical representation of a physical system at a non-zero temperature. It takes into account the thermal fluctuations and interactions between particles in the system, unlike a zero temperature matrix which only considers the ground state of the system.

2. How is a Finite Temperature matrix different from a zero temperature matrix?

A Finite Temperature matrix takes into account the effects of temperature on a physical system, while a zero temperature matrix only considers the ground state of the system. This means that a Finite Temperature matrix is more complex and includes interactions between particles, making it a more accurate representation of a real-world system.

3. What is the significance of Finite Temperature matrices in scientific research?

Finite Temperature matrices are crucial in studying and understanding the behavior of physical systems at non-zero temperatures, which is more relevant to real-world scenarios. They are used in a variety of fields such as condensed matter physics, quantum mechanics, and statistical mechanics to model and analyze the behavior of materials and particles.

4. How are Finite Temperature matrices calculated?

Finite Temperature matrices are typically calculated using statistical mechanics and thermodynamics principles. This involves considering the energy levels and interactions between particles in a system and applying mathematical techniques such as the partition function to determine the probabilities of different states at a given temperature.

5. What are some applications of Finite Temperature matrices?

Finite Temperature matrices have a wide range of applications in various scientific fields. They are used to study the properties of materials at different temperatures, analyze phase transitions, and model the behavior of quantum systems. They also have practical applications in technologies such as superconductors, semiconductors, and nanotechnology.

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