The difference between classical and quantum computing systems lies in the underlying principles they utilize for computation.
Classical Computing: Classical computing refers to the traditional form of computing that relies on classical physics and follows the principles of classical logic and binary digital representation. Classical computers use classical bits as the basic unit of information, which can exist in one of two states: 0 or 1. These bits are processed using logic gates and manipulated through electrical or optical signals. Classical computing operates sequentially, executing instructions one after another, and follows deterministic algorithms.
Quantum Computing: Quantum computing, on the other hand, is based on the principles of quantum mechanics, a branch of physics that governs the behavior of matter and energy at the atomic and subatomic levels. Quantum computers use quantum bits, or qubits, as the basic unit of information. Unlike classical bits, qubits can exist in a superposition of states, representing 0 and 1 simultaneously. This property allows quantum computers to perform multiple computations in parallel.
Quantum computing systems leverage two key principles of quantum mechanics: superposition and entanglement. Superposition enables qubits to hold multiple states simultaneously, while entanglement allows the correlation of qubits in such a way that the state of one qubit is entangled with the state of another, regardless of the physical distance between them.
A Hybrid Approach: A hybrid approach refers to the utilization of both classical and quantum computing systems together to solve computational problems. In a hybrid approach, certain parts of a problem or algorithm that are better suited for classical computation are processed on classical computers, while the parts that can benefit from quantum processing are offloaded to a quantum computer.
Hybrid computing is often employed due to the current limitations of quantum computers, such as error rates, limited qubit connectivity, and decoherence. By combining classical and quantum systems, the strengths of both approaches can be leveraged. The classical part of the computation can handle pre-processing, post-processing, or control tasks, while the quantum part focuses on solving the core computational problem.
This hybrid approach allows researchers and developers to make use of existing classical algorithms, software, and infrastructure, while harnessing the potential of quantum systems to address specific computational challenges. It also enables the gradual integration of quantum technologies into existing classical computing frameworks, making it more practical for real-world applications.