Eigenvalue

Definition

An eigenvalue is a special scalar associated with a linear transformation represented by an operator, where a corresponding eigenvector is not changed in direction by that transformation, only scaled. This concept is crucial in quantum mechanics, particularly in understanding the outcomes of measurements and the behavior of systems described by the Schrödinger equations. Eigenvalues help determine quantized states and observable properties of physical systems.

5 Must Know Facts For Your Next Test

1. Eigenvalues are fundamental to solving the time-independent Schrödinger equation, where they represent the allowed energy levels of a quantum system.
2. The eigenvalues of an operator can be determined by solving the characteristic equation, which is derived from the determinant of the operator minus the eigenvalue times the identity operator.
3. In quantum mechanics, measuring an observable corresponds to finding the eigenvalues of the associated operator, with each eigenvalue representing a potential outcome of the measurement.
4. Eigenvalues can be complex numbers in some contexts, especially when dealing with non-Hermitian operators, but in physical measurements, they must be real.
5. The set of all eigenvalues of an operator is known as its spectrum, which provides important information about the system's behavior and properties.

Review Questions

• How do eigenvalues relate to the time-independent Schrödinger equation in quantum mechanics?
  • In the context of the time-independent Schrödinger equation, eigenvalues represent quantized energy levels of a quantum system. When this equation is solved using an operator for energy, the eigenvalues emerge as specific values that correspond to stable states or allowed energies of a particle in a potential. The solutions that yield these eigenvalues are critical for predicting how systems behave at quantum scales.
• Discuss how operators and their properties influence the determination of eigenvalues in quantum mechanics.
  • Operators play a key role in determining eigenvalues, as they define how physical observables like momentum and position act on wave functions. The properties of operators, such as being Hermitian, ensure that their eigenvalues are real and correspond to measurable quantities. When applying an operator to find its eigenvalues, one must analyze how the operator interacts with wave functions and solve for conditions where certain wave functions remain unchanged except for scaling by these eigenvalues.
• Evaluate the significance of eigenvalues and their associated eigenvectors in interpreting physical measurements within quantum systems.
  • Eigenvalues and their associated eigenvectors are vital for interpreting measurements in quantum mechanics because they provide the possible results of an observable measurement. When an observable is measured, the system collapses into one of its eigenstates corresponding to an eigenvalue, which indicates the measured value. Understanding this relationship helps explain phenomena such as quantization and superposition in quantum systems, highlighting how theoretical concepts manifest in experimental outcomes.

Related terms

Eigenvector: An eigenvector is a non-zero vector that changes only by a scalar factor when a linear transformation is applied, corresponding to an eigenvalue.

Operator: An operator is a mathematical entity that acts on elements of a vector space, transforming them into other elements, often representing physical observables in quantum mechanics.

Hermitian Operator: A Hermitian operator is a special type of operator in quantum mechanics whose eigenvalues are real, ensuring that the observable quantities it represents can yield real measurement results.