Quantum Mechanics

Understanding the quantum world, wave-particle duality, and quantum phenomena

Topics

How do quantum computers work?

Quantum computers use quantum bits (qubits) that can exist in superposition (multiple states simultaneously) and entanglement (correlated states). This allows quantum computers to process many possibilities in parallel, potentially solving certain problems much faster than classical computers.

How does quantum mechanics work?

Quantum mechanics describes how particles behave at atomic and subatomic scales, where they exist in probability states rather than definite positions. Particles can be in multiple states simultaneously (superposition) until observed, and measurements affect what we observe.

How does quantum tunneling work?

Quantum tunneling occurs when particles pass through energy barriers they classically shouldn't be able to cross. Due to wave properties, particles have a probability of being found on the other side of barriers, even when their energy is less than the barrier height. This probability decreases exponentially with barrier width and height.

What is a quantum?

A quantum is the smallest discrete unit of a physical property. In quantum mechanics, many properties like energy, momentum, and angular momentum come in discrete packets (quanta) rather than continuous values. A photon is a quantum of light energy.

What is quantum entanglement?

Quantum entanglement is a phenomenon where two or more particles become correlated so that measuring one instantly affects the other, regardless of distance. Entangled particles share a quantum state and behave as a single system, even when separated.

What is quantum superposition?

Quantum superposition is the principle that quantum particles can exist in multiple states simultaneously until measured. A particle can be in a combination of different states (like spinning both up and down), with probabilities for each state. Measurement collapses the superposition to a single definite state.

What is Schrödinger's cat?

Schrödinger's cat is a thought experiment illustrating quantum superposition and the measurement problem. A cat in a box is simultaneously alive and dead until observed, representing how quantum particles exist in superposition until measured. It highlights the strange nature of quantum mechanics when applied to macroscopic objects.

What is the photoelectric effect?

The photoelectric effect occurs when light shining on a metal surface ejects electrons. Einstein explained it by proposing that light consists of particles (photons), with each photon's energy proportional to frequency. Only photons with sufficient energy can eject electrons, demonstrating light's particle nature.

What is the uncertainty principle?

The uncertainty principle states that we cannot simultaneously know precise values of certain pairs of properties, like position and momentum. The more precisely we know one, the less precisely we can know the other. This is a fundamental limit, not a measurement limitation.

What is wave-particle duality?

Wave-particle duality is the concept that particles like electrons and photons exhibit both wave-like and particle-like properties depending on how they're observed. They behave as particles in some experiments and as waves in others, showing that the classical distinction between waves and particles breaks down at the quantum level.