Quantum & Atomic Physics
8 terms
Quantum Decoherence
Quantum & Atomic Physics
s (Decoherence Time Constant)
The loss of quantum coherence where interaction between a quantum system and its macro-environment converts a quantum superposition into a classical probabilistic mixture.
ρ_offdiag(t) = ρ_offdiag(0) e^(-t / τ_dec)
Quantum Dots
Quantum & Atomic Physics
nm (Size), eV (Bandgap)
Nanometer-scale semiconductor crystals that trap charge carriers in all three spatial dimensions, exhibiting artificial atom quantized energy spectra.
E_gap(R) = E_bulk + (ℏ² π²) / (2 m_eff R²)
Quantum Electrodynamics (QED)
Quantum & Atomic Physics
Relativistic Quantum Field
The relativistic quantum field theory describing how light (photons) and charged matter (electrons/positrons) interact.
L_QED = ψ̄ (i γ^μ D_μ - m) ψ - ¼ F_μν F^μν
Quantum Entanglement
Quantum & Atomic Physics
Dimensionless Quantum State
A quantum phenomenon in which two or more particles become interconnected such that the quantum state of each particle cannot be described independently of the others.
|Ψ⟩ = (1 / √2) (|0⟩|1⟩ - |1⟩|0⟩)
Quantum Harmonic Oscillator
Quantum & Atomic Physics
eV or Joules
The quantum mechanical analogue of a classical harmonic oscillator, describing a particle bound in a parabolic potential well V(x) = ½ m ω² x².
E_n = (n + ½) ℏ ω, n = 0, 1, 2, 3...
Quantum Operators
Quantum & Atomic Physics
Varies by Observable
Linear mathematical operators that act on a wave function to yield physical observables (such as position, momentum, or energy).
p̂ = -i ℏ ∇, x̂ = x, Ĥ = -(ℏ² / (2m)) ∇² + V(x)
Quantum Superposition
Quantum & Atomic Physics
Dimensionless State Vector
A core principle of quantum mechanics stating that a quantum system can exist in a linear combination of multiple distinct quantum states simultaneously until measured.
|Ψ⟩ = α |0⟩ + β |1⟩, |α|² + |β|² = 1
Quantum Tunneling
Quantum & Atomic Physics
Dimensionless (Transmission Probability)
A quantum phenomenon where a particle passes through a potential energy barrier higher than the particle's kinetic energy.
T ≈ exp(-2 k L), k = √(2 m (V₀ - E)) / ℏ