Quantum information science is an interdisciplinary field that combines the principles of quantum mechanics, information theory, and computer science to explore how quantum phenomena can be harnessed for the processing, analysis, and transmission of information. Quantum information science covers both theoretical and experimental aspects of quantum physics, including the limits of what can be achieved with quantum information. The term quantum information theory is sometimes used, but it refers to the theoretical aspects of information processing and does not include experimental research.
At its core, quantum information science explores how information behaves when stored and manipulated using quantum systems. Unlike classical information, which is encoded in bits that can only be 0 or 1, quantum information uses quantum bits or qubits that can exist simultaneously in multiple states because of superposition. Additionally, entanglement—a uniquely quantum linkage between particles—enables correlations that have no classical counterpart.