Acronyms

A list of common acronyms you’ll encounter in quantum computing, quantum information, and quantum cryptography.

B

• BB84: Bennett-Brassard 1984 (QKD protocol) - see BB84 Protocol

C

• CNOT: Controlled-NOT (gate) - see CNOT Gate
• CZ: Controlled-Z (gate)

E

• E91: Ekert 1991 (QKD protocol) - see E91 Protocol
• EPR: Einstein-Podolsky-Rosen (paradox/pair)

F

• FTQC: Fault-Tolerant Quantum Computing - see Fault-Tolerant Quantum Computing

G

• GHZ: Greenberger-Horne-Zeilinger (state)

N

• NISQ: Noisy Intermediate-Scale Quantum - see NISQ

P

• PQC:
  • Post-Quantum Cryptography - see Post-Quantum Cryptography
  • Parameterized Quantum Circuit - see Parameterized Quantum Circuit

Q

• QAOA: Quantum Approximate Optimization Algorithm - see QAOA
• QC: Quantum Computing/Computer
• QEC: Quantum Error Correction - see Quantum Error Correction
• QFT: Quantum Fourier Transform - see Quantum Fourier Transform
• QKD: Quantum Key Distribution - see Quantum Key Distribution
• QML: Quantum Machine Learning - see Quantum Machine Learning
• QNN: Quantum Neural Network - see Quantum Neural Network
• QPE: Quantum Phase Estimation - see Quantum Phase Estimation
• QPU: Quantum Processing Unit
• QRNG: Quantum Random Number Generator - see Quantum Random Number Generator

R

• RSA: Rivest-Shamir-Adleman (cryptosystem)

V

• VQA: Variational Quantum Algorithm - see Variational Quantum Algorithm
• VQE: Variational Quantum Eigensolver - see VQE

Common Notation

• |ψ⟩: Ket notation for a quantum state (pronounced “ket psi”)
• ⟨ψ|: Bra notation (pronounced “bra psi”)
• ⟨ψ|φ⟩: Inner product (pronounced “bra-ket” or “bracket”)
• |0⟩, |1⟩: Computational basis states
• |+⟩, |−⟩: Hadamard basis states, $|+⟩=\frac{1}{\sqrt{2}}(|0⟩+|1⟩)$
• ⊗: Tensor product (combining quantum systems)
• †: Dagger (Hermitian conjugate)
• I: Identity operator
• ρ: Density matrix
• H: Hadamard gate (or Hamiltonian, depending on context)
• X, Y, Z: Pauli matrices/gates
• T₁, T₂: Relaxation and dephasing times

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