Quantum optics is the study of how light (photons) interacts with matter at the quantum level. Unlike classical optics, which treats light as a continuous wave, quantum optics treats light as being made up of discrete packets — photons — and explores their behavior in systems where quantum effects dominate.
Key Concepts:
- Quantization of light: Light is composed of photons, each carrying a quantum of energy.
- Coherence and entanglement: Quantum optics investigates how photons can be in superposition, become entangled, or interfere in non-classical ways.
- Single-photon sources and detectors: Essential for observing quantum effects in optics.
- Light-matter interactions: Describes how atoms, ions, or molecules absorb, emit, or scatter photons in ways governed by quantum mechanics.
Important Phenomena:
- Spontaneous and stimulated emission
- Quantum entanglement of photons
- Quantum interference (e.g., in beam splitters or interferometers)
- Photon antibunching, a signature of non-classical light
Applications:
- Quantum communication (e.g., quantum cryptography)
- Quantum computing with photonic qubits
- Ultra-precise measurement techniques
- Tests of fundamental quantum mechanics
Quantum optics lies at the heart of modern quantum technologies, enabling us to harness the strange and powerful properties of light in entirely new ways.