Ordinary classical computers, such as the ones we use today, operate based on classical physics and follow the laws of classical mechanics. They process information using bits, which are binary units representing either 0 or 1. These bits are manipulated using logic gates, allowing for calculations and data processing.
On the other hand, quantum computers operate on the principles of quantum mechanics, which govern the behavior of particles on a very small scale. Quantum computers use quantum bits, or qubits, which can represent 0, 1, or a superposition of both states simultaneously. This ability to exist in multiple states simultaneously is one of the fundamental differences between classical and quantum computing.
Additionally, qubits can exhibit a property called entanglement, where the states of multiple qubits become correlated in such a way that the state of one qubit is dependent on the state of another, even if they are physically separated. Entanglement allows for parallel processing and can be utilized to perform certain computations more efficiently than classical computers.
The computational power of quantum computers arises from the unique properties of qubits, such as superposition and entanglement. These properties enable quantum computers to perform certain types of calculations exponentially faster than classical computers for specific algorithms, such as Shor's algorithm for factoring large numbers.
Simulating quantum systems on classical computers is challenging because fully simulating a quantum system with a large number of qubits becomes exponentially difficult due to the exponential growth in the required computational resources. As the number of qubits increases, the classical computational resources required to accurately simulate the behavior of the quantum system become impractical.
While classical computers can simulate some aspects of quantum systems and perform calculations related to quantum phenomena, they cannot efficiently simulate the behavior of large-scale quantum systems or provide the same computational advantages as true quantum computers.
In summary, classical computers operate based on classical physics and manipulate classical bits, while quantum computers leverage the principles of quantum mechanics and use qubits to represent and process information in quantum states. The unique properties of qubits, such as superposition and entanglement, give quantum computers their potential for exponentially faster computation in certain cases, which cannot be fully replicated by classical computers.