In quantum teleportation, a specific quantum state is transferred from one qubit to another, without physically moving the qubit itself. The process involves a phenomenon called entanglement, which is a fundamental feature of quantum mechanics.
Here's a simplified explanation of how quantum teleportation works with three qubits:
The three qubits involved are typically referred to as the "sender" qubit (the one whose state is to be teleported), the "entangled pair" qubits (previously entangled qubits shared between the sender and the receiver), and the "receiver" qubit (the qubit that will receive the teleported state).
The sender qubit is entangled with one of the entangled pair qubits. This entanglement creates a correlation between the sender qubit and the other qubit of the entangled pair.
A measurement is performed on the sender qubit and the other qubit of the entangled pair. This measurement yields two classical bits of information.
The measurement results are then communicated from the sender to the receiver using classical communication channels. This communication does not involve the transmission of any quantum information; it only transmits classical information.
Based on the measurement results, the receiver applies specific quantum operations on their entangled qubit. These operations effectively transform the receiver's qubit into an exact replica of the sender's qubit, which is the teleported state.
Regarding the speed of quantum teleportation, it's important to note that the process itself does not involve the instantaneous transfer of information. The classical communication of the measurement results from the sender to the receiver is limited by the speed of light. Therefore, the transfer of information in quantum teleportation is subject to the same limitations as classical communication channels.
As for the concept of entanglement-based communication, there are restrictions on using entanglement for faster-than-light communication. This restriction is due to a fundamental principle in physics known as the no-communication theorem. The no-communication theorem states that it is not possible to use entanglement to transmit information faster than the speed of light.
Although entangled particles can exhibit correlated behavior over vast distances, the entanglement itself does not allow for direct communication or information transfer. The measurement results obtained from entangled particles are random and cannot be controlled or influenced to convey specific information. Therefore, while entanglement plays a crucial role in quantum teleportation, it cannot be exploited for superluminal communication.
It's worth noting that the field of quantum communication and quantum teleportation is an active area of research, and new discoveries and developments may further deepen our understanding of these concepts in the future.