Quantum Computing

General overview of Quantum Computing

Quantum computing is a new field that merges quantum mechanics with the idea of computability. Quantum computers are rather unique compared to classical and alternative methods of computation. They work on quantum data, which is manipulated using quantum gates that are quite different from classical logic gates. A sequence of these gates is called a quantum circuit, which is used to perform algorithms. Quantum computers are capable of solving complex problems significantly faster and more cost-efficiently than classical computers; such problems could take thousands of years for today’s supercomputers to resolve.

We are currently living in the noisy intermediate-scale quantum (NISQ) era. Although quantum computing is still in its early stages, it has already demonstrated promising results and speed-ups compared to what classical computers can offer today. It has been applied to develop more efficient manufacturing processes in quantum chemistry by analyzing certain molecular and photochemical properties. Additionally, Shor's algorithm has proven that modern cryptographic schemes, like RSA and ECDH, are threatened to be broken once a powerful enough quantum computer is developed.

Understanding quantum computing requires grasping its fundamental principles, including superposition, entanglement, and the functioning of qubits. Superposition allows particles, such as electrons, to exist in multiple states simultaneously, collapsing into a single state when measured. This principle underpins qubits, the basic units of information in quantum systems, which differ from classical bits by existing in multiple states at once, thus vastly enhancing computational capabilities. Entanglement, another core concept, links particles so that the state of one directly affects the other, even across vast distances—a phenomenon famously described by Einstein as "spooky action at a distance."

Qubits are the quantum equivalent of classical computer bits. They are typically created by manipulating particles, such as photons, electrons, trapped ions, or atoms. Once they are under low-enough temperatures and governed by the laws of quantum mechanics, qubits exhibit phenomena like superposition and entanglement. These phenomena challenge the classical physics perspective and drive the groundbreaking potential of quantum computing.