Quantum Computing Glossary

Adiabatic Quantum Computing is a model of quantum computation that solves problems by keeping a system in its ground state while slowly changing the Hamiltonian.

Amazon Braket is an Amazon Web Services (AWS) cloud platform that provides access to different quantum computers and simulators for running quantum algorithms.

Amplitude Amplification is a quantum algorithm technique that systematically increases the probability amplitude of a desired quantum state, making it more likely to be measured.

Amplitude Estimation is a quantum algorithm that efficiently estimates the amplitude of a particular quantum state, which is directly related to the probability of measuring that state.

Anyon is a quasiparticle in two-dimensional systems whose quantum statistics are between those of fermions and bosons, a property known as fractional statistics.

Bacon-Shor Code is a subsystem quantum error-correcting code that protects information on a 2D grid of qubits using simplified error checks on qubit rows and columns.

Barren Plateau is a phenomenon in variational quantum algorithms where the cost function landscape becomes exponentially flat, making optimization extremely difficult as gradients vanish.

BB84 Protocol is a method of quantum key distribution that securely shares a secret encryption key between two parties using single photons and their quantum properties.

Bell Inequality is a mathematical expression that, when violated by experimental results, proves quantum mechanics is incompatible with classical theories of local realism.

Bell State is one of four specific, maximally entangled states of two qubits whose measurement outcomes are perfectly correlated, regardless of the distance separating them.

Bernstein-Vazirani Algorithm is a quantum algorithm that efficiently finds a hidden bit string by querying an oracle just once, showcasing a clear speedup over classical methods.

Bit-Flip Error is an error where a qubit's state unintentionally flips from |0⟩ to |1⟩ or vice versa, analogous to a classical computer's bit flipping.

Blind Quantum Computing is a protocol that allows a client to perform computations on a remote quantum server without revealing the input, algorithm, or output.

Bloch Sphere is a geometric representation of a single qubit state as a point on the surface of a unit sphere.

Born Rule is a fundamental principle in quantum mechanics that gives the probability of obtaining a specific measurement outcome from a quantum system's wave function.

Bosonic Code is a quantum error correction approach that encodes a logical qubit in the infinite-dimensional state space of a quantum harmonic oscillator.

BQP is the class of problems a quantum computer can solve efficiently with a bounded error probability, representing the fundamental power of ideal, fault-tolerant quantum computation.

Braiding is the process of physically swapping quasiparticles, like anyons, in a 2D system. The computation's result is encoded in the topology of their intertwined spacetime paths.

Cat Qubit is a bosonic qubit encoded in a superposition of two coherent states in a microwave cavity, named after Schrodinger's cat thought experiment.

Charge Qubit is a type of superconducting qubit where quantum information is encoded in the number of electron pairs (Cooper pairs) on a tiny superconducting island.

Choi-Jamiolkowski Isomorphism is a mathematical duality that maps any quantum channel (a process or operation) to a unique, corresponding bipartite quantum state (a static object).

CHSH Inequality is a test used in quantum physics to prove that entanglement is a genuinely non-local phenomenon, ruling out classical explanations for observed correlations.

Circuit Optimization is the process of reducing the resources, such as the number of quantum gates or circuit depth, required to implement a quantum algorithm.

Cirq is Google's open-source Python framework for designing, simulating, and running quantum circuits on Google's quantum processors.

Classical Shadow is a method for efficiently learning properties of a quantum state by constructing a compact, classical description from a small number of randomized measurements.

Classical vs Quantum Computing is the comparison between traditional binary computation and computation exploiting quantum mechanical phenomena like superposition and entanglement.

Clifford Gate is a class of quantum gates, including Hadamard, CNOT, and S gates, that can be efficiently simulated classically but are insufficient alone for universal quantum computation.

Cluster State is a specific type of highly entangled multi-qubit quantum state used as the primary resource for one-way, or measurement-based, quantum computing.

CNOT Gate is a fundamental two-qubit operation that flips a target qubit's state only when its corresponding control qubit is in the state |1⟩, acting like a conditional switch.

Coherence is a qubit's ability to reliably maintain its quantum state, like superposition or entanglement, over time before being disrupted by environmental noise.

Color Code is a type of topological quantum error correction code that protects quantum information using a two-dimensional lattice whose faces can be colored with three colors.

Computational Basis is the set of fundamental states, |0⟩ and |1⟩, used to measure and describe a qubit, analogous to the 0s and 1s of classical computing.

Controlled Gate is a quantum operation applied to a target qubit only when a separate control qubit is in a specific state, acting as a conditional switch.

Cost Function Landscape is a multi-dimensional surface where elevation represents the 'cost' for a given set of parameters, with valleys indicating optimal solutions for an optimization problem.

Cross-Entropy Benchmarking is a statistical method that measures a quantum processor's performance by comparing its output from random circuits to the theoretically predicted, ideal output distribution.

Cryogenics is the science and engineering of achieving and maintaining ultra-low temperatures required to operate superconducting quantum processors.

Decoherence is the loss of quantum information from a qubit due to unwanted interaction with its surrounding environment.

Density Matrix is a mathematical operator that generalizes the concept of a quantum state, describing not just pure states but also probabilistic mixtures of states due to noise.

Depolarizing Channel is a common model for quantum noise where a qubit's state is either left untouched or, with some probability, replaced by a completely random, mixed state.

Deutsch-Jozsa Algorithm is a deterministic quantum algorithm that efficiently determines if a function is either constant (same output) or balanced (equal mix of outputs) in one evaluation.

Dilution Refrigerator is a cryogenic device that cools quantum processors to millikelvin temperatures using a mixture of helium-3 and helium-4.

Dynamical Decoupling is a quantum control technique that uses a sequence of applied pulses to protect qubits from environmental noise and suppress decoherence.

E91 Protocol is a quantum key distribution method using entangled particle pairs to create a shared secret key, with security guaranteed by the laws of quantum mechanics.

Eastin-Knill Theorem is a fundamental limit in quantum computing stating that no quantum error-correcting code can possess a universal, fault-tolerant set of transversally implemented logical gates.

Entanglement is a quantum correlation between two or more qubits such that the state of one instantly influences the state of another.

Error Threshold is the highest error rate a quantum computer can have per operation while still allowing quantum error correction to effectively fix errors for reliable computation.

Fault-Tolerant Quantum Computing is a regime where quantum error correction enables arbitrarily long computations despite physical qubit errors.

Fibonacci Anyon is a type of quasiparticle whose braiding operations are computationally universal and whose fusion rules mimic the Fibonacci sequence, used in topological quantum computing.

Floquet Code is a dynamic quantum error correction scheme that protects information by repeatedly applying a sequence of gates, creating an error-resilient state through periodic driving.

Flux Qubit is a type of superconducting qubit where quantum states are defined by the direction of persistent current flowing in a superconducting loop.

Fredkin Gate is a universal, reversible 3-qubit gate that conditionally swaps two target qubits based on the state of a single control qubit.

Gate Decomposition is the process of breaking down a complex quantum gate into a sequence of simpler, universal gates that a specific quantum processor can physically execute.

Gate Fidelity is a measure of how accurately a real-world quantum gate performs its intended operation, quantifying the difference between the actual gate and a perfect, theoretical one.

GHZ State is a multi-qubit entangled state where all qubits are perfectly correlated, existing in a superposition of all being 0 or all being 1 simultaneously.

Gottesman-Knill Theorem is a principle stating that quantum circuits composed exclusively of Clifford gates, preparation, and measurement in the computational basis can be efficiently simulated by a classical computer.

Grover's Algorithm is a quantum search algorithm that finds a marked item in an unsorted database with a quadratic speedup over classical search.

Hadamard Gate is a fundamental quantum logic gate that transforms a qubit from a definite state (0 or 1) into an equal superposition of both states, and vice-versa.

HHL Algorithm is a quantum algorithm for solving systems of linear equations, potentially offering an exponential speedup over classical methods for certain types of problems.

Holevo Bound is an upper limit on the amount of accessible classical information that can be extracted from a given quantum state through measurement.

Hybrid Quantum-Classical Computing is a method that combines classical computers for simple tasks and quantum processors for complex computations they are uniquely suited to solve.

Josephson Junction is a quantum electronic device consisting of two superconductors separated by a weak link, which allows a current to flow without any voltage.

Kochen-Specker Theorem is a no-go theorem in quantum mechanics proving that properties of a quantum system cannot have predetermined, context-independent values before they are measured.

Kraus Operators is a mathematical framework used to describe the evolution of a quantum state when it interacts with an environment, a process also known as a quantum channel.

Lattice Surgery is a technique for performing logical operations on surface code qubits by merging and splitting their lattice boundaries.

Logical Qubit is a robust unit of quantum information encoded across multiple physical qubits to protect it from errors and environmental noise known as decoherence.

Magic State Distillation is a process that purifies noisy quantum states into high-fidelity resource states needed to implement non-Clifford gates fault-tolerantly.

Majorana Fermion is an exotic quasiparticle that is its own antiparticle, proposed as the basis for topological qubits with built-in error protection.

Measurement is the process of observing a qubit, collapsing its superposition into a definite classical state of 0 or 1.

Measurement-Based Quantum Computing is a method where computation proceeds via single-qubit measurements on a highly entangled resource state, rather than applying a sequence of quantum gates.

Microwave Control is the technique of using precisely shaped microwave pulses to manipulate the quantum state of a qubit, executing quantum gate operations.

Neutral Atom Qubit is a quantum bit using the energy levels of a single uncharged atom, held in place by lasers, to encode quantum information.

NISQ is the Noisy Intermediate-Scale Quantum era, describing current quantum computers that have tens to hundreds of error-prone qubits without full error correction.

Nitrogen-Vacancy Center is a specific atomic defect in diamond, where a nitrogen atom substitutes a carbon atom next to a vacant site, creating a stable, addressable qubit.

No-Cloning Theorem is a fundamental principle stating it's impossible to create an identical, independent copy of an arbitrary, unknown quantum state.

Parameterized Quantum Circuit is a quantum circuit where some gates have adjustable parameters, which are tuned by a classical computer to help solve a problem.

Parametric Amplifier is a low-noise microwave device that boosts faint quantum signals from qubits for high-fidelity measurement, without adding significant noise that would corrupt the information.

Pauli Gates is a set of three fundamental quantum gates (X, Y, Z) that perform 180-degree rotations of a qubit on the Bloch sphere.

Pauli Twirling is a technique that transforms complex quantum noise into a simpler, more manageable form by averaging over applications of random Pauli gates.

PennyLane is an open-source Python library for differentiable programming of quantum computers, uniting quantum computing with machine learning.

Phase-Flip Error is a quantum error that reverses the relative phase of a qubit's superposition states, without affecting the probability of measuring it as |0⟩ or |1⟩.

Photonic Quantum Computing is an approach that uses photons, particles of light, as qubits to perform quantum computations at room temperature.

Physical Qubit is the actual, tangible hardware component—like a single atom or superconducting circuit—that embodies a qubit but is susceptible to noise and errors.

Post-Quantum Cryptography is a set of classical cryptographic algorithms designed to be secure against cryptanalytic attacks launched by both classical and powerful quantum computers.

Probabilistic Error Cancellation is a quantum error mitigation technique that models hardware noise and runs additional circuits to statistically cancel out errors from the final result.

Pulse-Level Control is the practice of directly manipulating the precise microwave or laser pulses sent to a quantum processor to implement quantum gates and operations.

QAOA is the Quantum Approximate Optimization Algorithm, a variational hybrid algorithm for finding approximate solutions to combinatorial optimization problems.

Qiskit is IBM's open-source quantum computing SDK for building, simulating, and executing quantum circuits on IBM quantum hardware.

QMA is a computational complexity class, the quantum analog of NP, that contains decision problems whose solutions can be efficiently verified by a quantum computer given a quantum proof.

Quantum Advantage is the demonstrated ability of a quantum computer to solve a practical problem faster or better than the best classical alternative.

Quantum Algorithm is a step-by-step procedure designed to run on a quantum computer, exploiting quantum effects to solve problems efficiently.

Quantum Amplitude Encoding is a method for representing a normalized vector of classical data by mapping its values onto the probability amplitudes of a quantum state.

Quantum Annealing is a quantum computing paradigm that solves optimization problems by slowly evolving a system toward its lowest energy state.

Quantum Approximate Counting is a quantum algorithm that efficiently estimates the number of solutions to a search problem, providing quadratic speedup over classical brute-force methods.

Quantum Benchmark is a standardized procedure used to measure, evaluate, and compare the performance and capabilities of different quantum computing systems.

Quantum Bit Error Rate is the probability that a qubit measurement yields an incorrect result, quantifying the noise level in a quantum system.

Quantum Capacity is the highest rate at which quantum information, such as qubits, can be reliably transmitted over a noisy quantum channel using quantum error correction.

Quantum Channel is a communication medium that transmits quantum information, typically in the form of qubits, from one location to another while preserving its fragile quantum state.

Quantum Chemistry Simulation is the use of quantum computers to model molecular behavior and chemical reactions more accurately than classical methods allow.

Quantum Circuit is a sequence of quantum gates applied to qubits, representing a quantum computation from input to measurement.

Quantum Circuit Depth is the longest sequence of quantum gates in a circuit, determining the minimum time required for the computation to complete.

Quantum Cloud is a cloud-based service that provides remote access to real quantum processors and simulators over the internet.

Quantum Compiler is software that translates high-level quantum algorithms into optimized sequences of hardware-native gates for a specific quantum processor.

Quantum Complexity Theory is the study of computational resources needed for quantum computers to solve problems, classifying their difficulty and exploring the limits of quantum computation.

Quantum Computing Stack is the hierarchy of hardware and software layers required to translate high-level algorithms into physical operations on a quantum processor.

Quantum Contextuality is a non-classical property where the outcome of a measurement depends on which other compatible measurements are performed simultaneously.

Quantum Coupling is the controlled interaction between two or more qubits, allowing them to influence each other’s state and perform multi-qubit logic operations.

Quantum Cryptography is a communication method using quantum mechanics to secure information, making any attempt to eavesdrop immediately detectable.

Quantum Discord is a measure of non-classical correlations between quantum systems, capturing quantum connections that exist even in the absence of entanglement.

Quantum Dot is a tiny semiconductor crystal whose size dictates its electronic properties, allowing it to trap single electrons and behave like an artificial atom.

Quantum Entanglement Swapping is a procedure that creates entanglement between two qubits that have never interacted, by performing measurements on other previously entangled particles.

Quantum Error Correction is a set of techniques that protect quantum information from noise and decoherence by encoding it across multiple physical qubits.

Quantum Error Mitigation is a set of software techniques used to reduce the impact of noise on near-term quantum computers, without requiring full error correction.

Quantum Error Rate is a measure of how frequently errors occur in qubits or during quantum gate operations, affecting the reliability of a quantum computation.

Quantum Fidelity is a measure of the 'closeness' between two quantum states, often comparing an ideal state to the actual state produced by a noisy quantum computer.

Quantum Firmware is the low-level software layer that controls quantum hardware, translating gate instructions into precise microwave or laser pulse sequences.

Quantum Fourier Transform is a quantum algorithm that performs a Fourier transform on the amplitudes of a quantum state, changing it from the computational to the frequency domain.

Quantum Gate is a basic operation on qubits that transforms their quantum state, serving as the building block of quantum circuits.

Quantum Hamiltonian Simulation is using a controllable quantum computer to mimic the time evolution of another, less accessible quantum system described by its Hamiltonian.

Quantum Hardware is the physical machinery used to build and operate a quantum computer, including processors, control electronics, and cooling systems needed to manipulate qubits.

Quantum Interconnect is the hardware and protocol layer that links separate quantum processors together to enable modular, large-scale quantum computing.

Quantum Interference is the phenomenon where a qubit's multiple states combine, either reinforcing or canceling each other out to influence the final computational result.

Quantum Internet is a network that connects quantum devices, allowing them to exchange quantum information and leverage properties like entanglement for fundamentally secure communication.

Quantum Kernel Method is a technique that uses a quantum computer to map classical data into a high-dimensional quantum feature space, making complex patterns easier to classify.

Quantum Key Distribution is a secure communication method using quantum mechanics to exchange encryption keys, ensuring any eavesdropping attempt is immediately detected by the users.

Quantum LDPC Codes are a family of quantum error correction codes with low-density parity checks that promise lower qubit overhead than surface codes.

Quantum Machine Learning is the intersection of quantum computing and machine learning, exploring quantum algorithms that may accelerate or enhance ML tasks.

Quantum Memory is a device that can store a fragile quantum state, like a qubit, for a period of time without destroying the information it holds.

Quantum Money is a theoretical cryptographic protocol that uses unique quantum states to create unforgeable currency, secured by the fundamental laws of physics.

Quantum Network is a network that connects quantum computers and devices, allowing them to transmit information encoded in quantum states, such as qubits, over long distances.

Quantum Noise is random environmental interference that corrupts the delicate quantum state of a qubit, introducing errors into calculations and causing decoherence.

Quantum Oracle is a 'black box' function used in quantum algorithms that checks if an input is a solution, marking it without revealing the internal process.

Quantum Parallelism is a quantum computer's ability to perform a computation on many different input values simultaneously, thanks to the principle of superposition.

Quantum Phase is an intrinsic property of a qubit's superposition, describing the relative 'angle' between its 0 and 1 components, which is essential for quantum interference.

Quantum Phase Estimation is a core quantum algorithm used to determine the phase, or eigenvalue, of a given unitary operator's eigenvector.

Quantum Process Tomography is an experimental procedure for fully characterizing a quantum operation, revealing the mathematical map of what a gate or circuit actually does, including its errors.

Quantum Processor is the physical chip or device that hosts qubits and executes quantum gate operations.

Quantum Random Number Generator is a device that harnesses the inherent randomness of quantum mechanics, like superposition and measurement, to produce truly unpredictable numbers.

Quantum Register is a collection of multiple qubits used to store and manipulate quantum information, acting as the memory and workspace for a quantum computer.

Quantum Repeater is a device that extends the range of quantum communication by using entanglement swapping and quantum error correction to relay quantum states.

Quantum SDK is a software development kit providing tools, libraries, and APIs for writing and running quantum programs.

Quantum Sensor is a device that uses quantum mechanical properties, like superposition, to make extremely precise measurements of physical quantities beyond the limits of classical technology.

Quantum Signal Processing is a technique for precisely manipulating a single qubit's state using a sequence of simple rotation gates to construct a complex target operation.

Quantum Simulation is using a controllable quantum computer to model and understand the behavior of other complex quantum systems, like molecules or materials.

Quantum Singular Value Transformation is a framework for precisely manipulating matrices on a quantum computer, acting as a master key to unlock numerous quantum algorithms.

Quantum Software is the set of programs, languages, and instructions used to tell a quantum computer what calculations to perform and how to manipulate qubits.

Quantum Speedup is the ability of a quantum computer to solve certain problems exponentially or polynomially faster than the best-known classical computer.

Quantum State is the complete mathematical description of a quantum system, like a qubit, encompassing all its possible properties before it is measured.

Quantum State Preparation is the process of initializing a system of qubits into a specific, known starting state before a quantum computation begins.

Quantum Supremacy is the milestone where a quantum computer performs a specific task that no classical computer can complete in a feasible timeframe.

Quantum Teleportation is a process that transfers the exact quantum state of a particle to another, distant particle, without physically moving the original particle itself.

Quantum Tomography is the experimental process of fully characterizing an unknown quantum state or quantum process by making repeated measurements on identically prepared systems.

Quantum Tunneling is the quantum mechanical phenomenon where a particle passes through an energy barrier it classically should not be able to overcome.

Quantum Volume is a hardware-agnostic benchmark that measures the overall capability of a quantum computer, accounting for qubits, connectivity, and error rates.

Quantum Walk is the quantum mechanical analogue of a classical random walk, allowing a particle to explore many possible paths on a graph simultaneously through superposition.

Qubit is the fundamental unit of quantum information, analogous to a classical bit but capable of existing in superposition states.

Qubit Connectivity is the physical layout and ability of qubits on a quantum processor to interact and perform operations directly with each other.

Qubit Mapping is the process of assigning an algorithm's abstract logical qubits to the specific physical qubits on a quantum processor, respecting its hardware connectivity constraints.

Qubitization is a quantum algorithm technique for simulating Hamiltonians by embedding their evolution into a larger quantum circuit for efficient, high-precision implementation.

Randomized Benchmarking is a protocol for measuring the average error rate of a set of quantum gates by applying long, random sequences and observing performance decay.

Readout Fidelity is the probability of correctly measuring the state of a qubit. It quantifies how accurately we can distinguish between a qubit's '0' and '1' states.

Resonator is an electrical circuit that naturally oscillates at a specific microwave frequency, used to couple to, control, and measure the state of a superconducting qubit.

Rotation Gates is a class of quantum gates that continuously changes a qubit's state by rotating it around an axis on the Bloch sphere.

Shadow Tomography is a highly efficient method for predicting properties of a quantum state from a few measurements, without needing to reconstruct the entire state itself.

Shor's Algorithm is a quantum algorithm that factors large integers exponentially faster than the best known classical methods.

Silicon Spin Qubit is a quantum bit that uses the spin of an electron, trapped in a silicon-based structure like a quantum dot, to encode quantum information.

Simon's Algorithm is a quantum algorithm that finds a hidden period 's' within a specific type of function exponentially faster than any classical computer could.

SNAIL Amplifier is a superconducting parametric amplifier for high-fidelity, quantum-limited readout of qubit states, boosting weak microwave signals with minimal added noise.

Solovay-Kitaev Theorem is a key result showing that any quantum gate can be efficiently approximated by a short sequence of gates from a fixed, universal set.

Spin Qubit is a quantum bit that uses the intrinsic angular momentum (spin) of an electron or atomic nucleus to represent quantum information, such as 'spin-up' or 'spin-down'.

Stabilizer Code is a powerful class of quantum error correction codes that defines a protected quantum state by identifying it as one left unchanged by a specific group of check operators.

Steane Code is a foundational quantum error correction code that uses seven physical qubits to protect and encode one robust logical qubit against errors.

Stinespring Dilation is a fundamental theorem showing any quantum operation (channel) on a system can be represented as a unitary evolution on a larger, combined system.

Strawberry Fields is a full-stack Python library for designing, simulating, and executing programs on photonic quantum computers, developed by Xanadu.

Subsystem Code is a an advanced quantum error correction scheme that encodes logical information into a subsystem, offering greater flexibility for error detection than standard stabilizer codes.

Superconducting Qubit is a qubit made from superconducting electrical circuits that exhibit quantum behavior when cooled to millikelvin temperatures.

Superdense Coding is a quantum communication protocol allowing someone to send two classical bits of information by physically sending only one entangled qubit.

Superposition is a quantum mechanical property allowing a qubit to exist in a linear combination of the 0 and 1 states simultaneously.

Surface Code is a leading quantum error correction code that arranges physical qubits in a two-dimensional grid to protect a single logical qubit.

SWAP Gate is a two-qubit quantum gate that exchanges the quantum states of the two qubits involved, enabling information routing within a quantum circuit.

Syndrome Measurement is a technique in quantum error correction that identifies errors on qubits without destroying their computational state, revealing only information about the error itself.

T-Gate is a single-qubit quantum gate that applies a pi/8 phase rotation and is essential for achieving universal quantum computation.

T1 Relaxation Time is the characteristic time it takes for an excited qubit to decay, or 'relax,' from its |1⟩ state back to its ground |0⟩ state.

T2 Coherence Time is the maximum time a qubit can maintain its phase relationship in a superposition state before it's lost to environmental noise.

Threshold Theorem is the principle that a quantum computer can operate reliably for any length of time provided the error per gate is below a specific, critical value.

TKET is a retargetable quantum software development kit (SDK) and compiler from Quantinuum. It optimizes quantum circuits to run efficiently on diverse quantum hardware backends.

Toffoli Gate is a universal three-qubit gate, also known as CCNOT, that flips a target qubit if and only if two control qubits are both in the |1⟩ state.

Topological Order is a robust phase of quantum matter where information is stored non-locally in the global entanglement pattern, making it inherently resistant to local errors.

Topological Qubit is a theorized qubit that stores information in the global properties of a system, making it inherently resistant to local noise.

Toric Code is a foundational topological quantum error correction code that encodes logical information non-locally across many physical qubits arranged on a torus (a donut shape).

Transmon Qubit is a popular type of superconducting qubit, built from a non-linear electrical circuit that exhibits quantum behavior when cooled to near absolute zero.

Transpilation is rewriting a quantum circuit into a new, equivalent circuit that matches the constraints and native gate set of a specific quantum processor.

Trapped Ion is a quantum computing technology that uses individual ions confined by electromagnetic fields as qubits, manipulated with laser pulses.

Trotterization is a method for simulating the evolution of a quantum system by breaking it down into a sequence of smaller, manageable quantum gate operations.

Unitary Operator is a mathematical transformation, representing a quantum gate, that evolves a quantum state over time. This operation is always reversible and preserves total probability.

Universal Gate Set is a finite set of quantum gates that can be combined to approximate any possible quantum computation to a desired level of accuracy.

Variational Algorithm is a hybrid quantum-classical method where a classical computer iteratively tunes a quantum circuit's parameters to find an approximate solution to a complex problem.

Variational Quantum Eigensolver is a hybrid quantum-classical algorithm that finds the lowest energy state of a molecule or system using parameterized quantum circuits.

Von Neumann Entropy is a measure of the statistical uncertainty or 'purity' of a quantum state, quantifying how mixed or entangled it is with its environment.

W State is a specific multi-qubit entangled state where a superposition exists of exactly one qubit being in the |1⟩ state, with all others in the |0⟩ state.

Wave Function is a mathematical description of a quantum system, containing all possible information about its state before it is measured.

Zero-Noise Extrapolation is a quantum error mitigation technique that estimates a noiseless result by running a circuit at amplified noise levels and extrapolating to the zero-noise limit.