Quantum Mechanics Concepts Flashcards
What is quantum mechanics?
The theory of the mechanics governing extremely small systems, comparable to the size of atoms
Why was quantum mechanics developed?
To describe phenomena that classical mechanics was unable to explain
What are some phenomena that quantum mechanics explains?
- Theory of blackbodies
- Photoelectric effect
- Wave-like nature of particles
What is quantization?
The phenomenon in which certain quantities can only take certain discrete values
Who discovered the quantization of energy?
Max Planck
What are photons?
Individual particles of light
What is Planck’s constant represented by?
h
What is the reduced Planck’s constant represented by?
ħ (h-bar)
What is superposition in quantum mechanics?
The principle by which a quantum system can exist in a state that is a simultaneous combination of two or more discrete states
What does the Copenhagen interpretation state about superposition?
The particle is in neither state until observed
What does Schrödinger’s cat thought experiment illustrate?
The absurdity of superposition in quantum mechanics
What is wave-particle duality?
The idea that quantum systems can display both wave-like and particle-like properties
What is the work function in the context of the photoelectric effect?
The minimum energy threshold for electrons to be emitted from a metal
What is Heisenberg’s uncertainty principle?
The principle stating that certain pairs of properties cannot be known simultaneously with arbitrary precision
What does the uncertainty principle state mathematically?
The product of the standard deviation of position and momentum must be greater than h/4π
What is spin in quantum mechanics?
A form of intrinsic angular momentum possessed by elementary particles
What are fermions?
Particles with half-integer spin
What are bosons?
Particles with integer spin
What is quantum tunneling?
The phenomenon where a quantum particle passes through a potential energy barrier that it could not pass through classically
What is entanglement in quantum mechanics?
A phenomenon where the state of each particle cannot be described independently of the other particles
What does the Pauli exclusion principle state?
No two identical fermions can occupy the same quantum state at the same time
What is a Bose–Einstein condensate (BEC)?
A state of matter formed when a low-density gas of bosons is cooled to temperatures very close to absolute zero
What is a wavefunction?
A mathematical description of a quantum state in an isolated system
What does the square of the wavefunction represent?
The probability density of measuring a particle in a particular place
What is normalization in the context of wavefunctions?
The condition that the spatial integral of the wavefunction times its complex complement must equal one
What are operators in quantum mechanics?
Mathematical functions that act on wavefunctions to yield values of physical quantities called observables
What is the Hamiltonian operator?
The operator corresponding to total energy in quantum mechanics
What is the commutator of two operators?
A function that measures the degree to which the two operators obey the commutative property
What does the Schrödinger equation govern?
How the wavefunction changes in time and space
What does the time-independent Schrödinger equation state?
The Hamiltonian operator applied to the wavefunction equals energy times the wavefunction
What is the significance of the Schrödinger equation?
It can be seen as a quantum generalization of Newton’s second law
