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Quantum computing, in plain English.
Short, honest definitions — including what is still an open question. Then try the ideas yourself in the Lab.
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34 terms
- Backend adapterQAISS
- A proposed connector that translates the QAISS workload format to a specific simulator or provider.
- Circuit depthBasics
- The number of sequential gate layers. Deeper circuits take longer and accumulate more noise on real hardware.
- Classical baselineQAISS
- The best credible classical method for the same problem. Every QAISS comparison must include one.
- Crypto inventorySecurity
- A list of where an organization uses public-key cryptography — the first step of a post-quantum migration plan.
- DecoherenceHardware
- Loss of quantum information to the environment over time. It limits how long and how deep circuits can be.
- Density matrixSimulation
- A representation that can describe noisy, mixed quantum states. Costs more memory than a state vector.
- Ed25519Security
- The elliptic-curve signature scheme used by Solana accounts and transactions — including the QAISS token. Secure against classical computers; not resistant to Shor’s algorithm.
- EntanglementBasics
- Correlation between qubits that cannot be described one qubit at a time. The Bell state in the Lab is the simplest example.
- Error mitigationHardware
- Techniques that reduce the impact of noise on results without full error correction — often at the cost of extra runs.
- Grover’s algorithmAlgorithms
- Searches an unstructured set with quadratically fewer queries than classical brute force, in the ideal noise-free case.
- Grover’s algorithm (security view)Security
- Speeds up brute-force search quadratically. It weakens hashes and symmetric keys but does not break them; larger sizes (e.g. 256-bit) restore the margin.
- Harvest now, decrypt laterSecurity
- Recording encrypted data today in the hope of decrypting it once a capable quantum computer exists — the main reason to migrate long-lived secrets early.
- Hybrid quantum–classicalAlgorithms
- Workflows where classical computers prepare, optimize, and post-process, and a quantum processor runs selected parts.
- MeasurementBasics
- Reading out qubits. It produces classical bits and destroys the superposition, so experiments are repeated many times ("shots").
- ML-DSA (FIPS 204)Security
- NIST’s standardised lattice-based post-quantum digital signature (formerly CRYSTALS-Dilithium).
- ML-KEM (FIPS 203)Security
- NIST’s standardised post-quantum key-encapsulation mechanism, based on module lattices (formerly CRYSTALS-Kyber).
- Noise modelSimulation
- A description of errors (decoherence, gate errors, readout errors) used to make simulations resemble real devices.
- Post-quantum cryptographySecurity
- Classical cryptographic algorithms designed to resist attacks by future quantum computers. Standardized algorithms now exist.
- QAOAAlgorithms
- Quantum Approximate Optimization Algorithm: alternates cost and mixer layers to search for good solutions to combinatorial problems.
- Quantum advantageBasics
- A demonstrated case where a quantum method beats the best known classical method on a useful task. QAISS does not claim it.
- Quantum circuitBasics
- An ordered list of gates applied to qubits, followed by measurement.
- Quantum gateBasics
- A reversible operation on one or more qubits, represented as a unitary matrix — for example H (Hadamard), X, RZ, or CNOT.
- Quantum kernelAlgorithms
- Uses a quantum circuit to compute similarities between data points for machine learning. Its practical value is an open research question.
- QubitBasics
- The basic unit of quantum information. Unlike a bit, it can be in a superposition of 0 and 1 until it is measured.
- Readout errorHardware
- The chance that a measured bit is reported incorrectly. The Lab models it as an independent bit flip.
- Shor’s algorithmSecurity
- A quantum algorithm that factors integers and computes discrete logarithms efficiently. On a large fault-tolerant quantum computer it would break RSA and elliptic-curve signatures such as Ed25519 and ECDSA.
- ShotsBasics
- The number of times a circuit is run and measured to estimate outcome probabilities.
- SLH-DSA (FIPS 205)Security
- NIST’s standardised stateless hash-based post-quantum signature (formerly SPHINCS+), relying only on hash-function security.
- Stabilizer simulationSimulation
- Fast classical simulation of circuits built only from Clifford gates.
- State-vector simulationSimulation
- Classical simulation that stores every amplitude. Exact, but memory doubles with each qubit — about 16 GB at ~30 qubits in double precision.
- SuperpositionBasics
- A combination of basis states with complex amplitudes. Measurement returns one outcome with probability equal to the squared magnitude of its amplitude.
- Tensor-network simulationSimulation
- Represents a circuit as a network of tensors and contracts it. Efficient for some larger, low-entanglement circuits.
- VQEAlgorithms
- Variational Quantum Eigensolver: a hybrid method that tunes circuit parameters to estimate low energies of molecules or materials.
- Workload PassportQAISS
- The proposed QAISS manifest recording circuit, framework, backend, precision, noise model, seed, runtime, cost, output, and timestamp.
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