Quantum Operators and Observables

Home > Physics > Quantum Physics > Quantum Operators and Observables

Introduction to the operators and observables used to describe quantum systems, including Hamiltonians and eigenvalues.

Vector Spaces and Linear Algebra: Vectors and matrices are used to represent states and operations in quantum mechanics. Linear algebra concepts like basis, eigenvalues, and eigenvectors are important in understanding quantum operators and observables.
Bra-Ket Notation: This notation is used to represent quantum states and operators in a concise and elegant way. In this notation, the state vector is written as a ket and its conjugate transpose is written as a bra.
Operators and Observables: Operators in quantum mechanics are mathematical objects that act on quantum states. Observable quantities like energy, position, and momentum are represented by corresponding Hermitian operators in quantum mechanics.
Commutation Relations: The commutator of two operators is a measure of how they interact with each other. Commutation relations are important in determining the properties of quantum states and the measurement outcomes of observables.
Uncertainty Principle: The uncertainty principle relates the uncertainty in the measurement of two non-commuting observables. It states that the product of the uncertainties in the measurement of the position and momentum of a particle cannot be smaller than a certain value.
Eigenvalue Problem: Finding eigenvectors and eigenvalues of operators is an important problem in quantum mechanics. The eigenvectors of an operator correspond to the possible values of the observable that it represents.
Schrödinger Equation: The Schrödinger equation is the fundamental equation of quantum mechanics. It describes the time evolution of quantum states under the influence of a Hamiltonian operator.
Hilbert Space: The state vectors in quantum mechanics live in a Hilbert space, which is a complex vector space equipped with an inner product. Quantum mechanics requires that states be normalizable, which means that their norms are finite.
Quantum Mechanics in Three Dimensions: In three dimensions, the position and momentum operators are represented by vectors. The angular momentum operator is an important observable in this setting, and its eigenstates are spherical harmonics.
Density Operators and Mixed States: When a quantum system is in a mixed state, its state cannot be represented by a single vector in Hilbert space. Instead, it is represented by a density operator, which captures the probabilities of different pure states in the mixture.
Position Operator: This operator measures the position of a particle in space.
Momentum Operator: This operator measures the momentum of a particle.
Energy Operator: This operator measures the energy of a particle.
Spin Operator: This operator measures the spin angular momentum of a particle.
Angular Momentum Operator: This operator measures the angular momentum of a particle.
Time Operator: This operator measures the time evolution of a quantum system.
Hamiltonian Operator: This operator describes the total energy of a quantum system.
Density Operator: This operator describes the statistical properties of the wave function of a quantum system.
Pauli Operators: These are a special set of spin operators that are commonly used to study the properties of qubits (quantum bits) in quantum computing.
Creation and Annihilation Operators: These operators create and destroy particles in quantum systems.
Phase Operator: This operator measures the phase of a quantum state.
Measurement Operator: This operator is used to perform measurements on quantum systems, which can collapse the wave function of the system.