$ \newcommand{\braket}[1]{\langle #1 \rangle} \newcommand{\abs}[2][]{\left\lvert#2\right\rvert_{\text{#1}}} \newcommand{\ket}[1]{\left\lvert#1 \right.\rangle} \newcommand{\bra}[1]{\langle\left. #1\right\rvert} \newcommand{\braket}[1]{\langle #1 \rangle} \newcommand{\dd}{\text{d}} \newcommand{\dv}[2]{\frac{\dd #1}{\dd #2}} \newcommand{\pdv}[2]{\frac{\partial}{\partial #1}} $
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Overview
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Concepts
The density matrix is a matrix which represents the state of a mixed state.

Notations

The density matrix is denoted $\rho$, where $$\begin{align*} \rho=\sum_{i=1}^m p_i|\psi_i\rangle \langle \psi_i| \end{align*}$$

Concepts

The density matrix comes from the expectation value calculation and simplifies it so all we need is the operator, density matrix, and eigenstates, instead of a general state $|\psi\rangle$.
The density matrix is a matrix which represents the state of a mixed state.

Notations

The density matrix is denoted $\rho$, where $$\begin{align*} \rho=\sum_{i=1}^m p_i|\psi_i\rangle \langle \psi_i| \end{align*}$$

Concepts

The density matrix comes from the expectation value calculation and simplifies it so all we need is the operator, density matrix, and eigenstates, instead of a general state $|\psi\rangle$.
FullPage
Overview
Notations
Concepts
FullPage
Overview
Notations
Concepts
The density matrix is a matrix which represents the state of a mixed state.

Notations

The density matrix is denoted $\rho$, where $$\begin{align*} \rho=\sum_{i=1}^m p_i|\psi_i\rangle \langle \psi_i| \end{align*}$$

Concepts

The density matrix comes from the expectation value calculation and simplifies it so all we need is the operator, density matrix, and eigenstates, instead of a general state $|\psi\rangle$.
The density matrix is a matrix which represents the state of a mixed state.

Notations

The density matrix is denoted $\rho$, where $$\begin{align*} \rho=\sum_{i=1}^m p_i|\psi_i\rangle \langle \psi_i| \end{align*}$$

Concepts

The density matrix comes from the expectation value calculation and simplifies it so all we need is the operator, density matrix, and eigenstates, instead of a general state $|\psi\rangle$.
FullPage
Overview
Notations
Concepts