Explain major definitions of "quantum computing" and how they differ
The term “quantum computing” has several major definitions, reflecting distinct theoretical, practical, and engineering perspectives. These definitions vary because researchers emphasize different aspects of how quantum principles are applied to computation.?
1. Quantum-Mechanical DefinitionFrom a physics standpoint, a quantum computer is a system that uses superposition, entanglement, and interference of quantum states to perform operations that are impossible or exponentially slower on classical machines.?
- Information is represented by qubits, which can exist in multiple states simultaneously (superposition).
- Entanglement allows correlated qubits to act as a unified system.
- Computation arises from manipulating these states and amplifying desired outcomes via interference.
This definition centers on physical principles—quantum coherence and probabilistic measurement—as integral to the computational process.?
2. Information-Theoretic DefinitionIn computational theory, quantum computing is defined as a paradigm of computation over complex probability amplitudes rather than discrete bits. Operations are expressed mathematically through linear algebra (unitary transformations and matrix operations), not Boolean logic. This view abstracts away hardware and focuses on how information evolves through reversible, probabilistic transformations governed by the Schrödinger equation.?
3. Engineering and Industry DefinitionTechnology companies like IBM, Microsoft, and AWS define quantum computing as a multidisciplinary technology integrating computer science, physics, and engineering that seeks to solve problems beyond the reach of classical computation.?
- Quantum processors (QPUs) operate qubits physically implemented in superconducting circuits, trapped ions, or photonic systems.?
- The field includes hybrid approaches combining classical and quantum subsystems for optimization and simulation tasks.?
This practical definition emphasizes technological readiness and scaling challenges—error correction, decoherence, and qubit fidelity—as the defining features of progress.
4. Philosophical and Foundational DefinitionPhilosophers and foundational theorists describe quantum computing as a conceptual framework redefining computation itself—treating the act of measurement and physical evolution as an inseparable part of information processing.?
This definition highlights the epistemic difference between quantum and classical computation: in quantum systems, information is not merely stored or processed, but embodied in probabilistic physical phenomena.
Distinctions Among Definitions
PerspectiveCore FocusKey TermsWhat Makes It Distinct<tbody]| quantum-mechanical<="" td=""] | physical="" phenomena<="" td=""] | superposition,="" entanglement<="" td=""] | emphasizes="" exploiting="" quantum="" states="" directly="" for="" computation ?<="" td=""] | | information-theoretic<="" td=""] | mathematical="" formalism<="" td=""] | unitary="" operations,="" amplitude="" interference<="" td=""] | treats="" computation="" as="" manipulation="" of="" vectors="" in="" hilbert="" space ?<="" td=""] | | engineering="" industry<="" td=""] | hardware="" and="" scalability<="" td=""] | qubits,="" coherence,="" error="" correction<="" td=""] | focuses="" on="" building="" functional="" and="" scalable="" qpus ?<="" td=""] | | philosophical<="" td=""] | nature="" of="" information<="" td=""] | measurement,="" non-determinism<="" td=""] | explores="" how="" computation="" is="" redefined="" when="" measurement="" alters="" data ?<="" td=""] |
In essence, these definitions differ primarily in what they consider the essential feature of quantum computation—whether it is the physics, the mathematics, the technology, or the concept of computation itself. |
