In quantum computing, quantum teleportation is a process that allows the transfer of the quantum state of one qubit to another qubit, which are typically referred to as the sender (Alice) and the receiver (Bob). However, it is important to note that quantum teleportation does not involve the actual physical transfer of information or particles between qubits.
The process of quantum teleportation involves three qubits and classical communication between Alice and Bob. Here's a simplified explanation of how it works:
Initialization: Initially, Alice and Bob share an entangled pair of qubits, often referred to as a Bell pair. Alice also has a qubit that she wants to teleport to Bob.
Entanglement: Alice applies a series of quantum operations, including a controlled-NOT (CNOT) gate and a Hadamard gate, on her qubit and the qubit she wants to teleport. Then, she performs a measurement on both qubits.
Measurement and Communication: Alice's measurement results in two classical bits of information. She sends these two classical bits to Bob through classical communication.
Bob's Operations: Based on the information received from Alice, Bob performs specific quantum operations on his qubit, which is part of the entangled pair he shares with Alice. These operations depend on the measurement results and effectively transfer the state of Alice's original qubit to Bob's qubit.
The process described above does not involve the physical transfer of the qubit itself. Instead, the quantum state of Alice's qubit is transferred to Bob's qubit through the entanglement and the classical communication of measurement results.
Regarding the question of whether the communication for entanglement is instantaneous, it is crucial to understand that entanglement does not allow for faster-than-light communication. Although entanglement is a phenomenon where the quantum states of two or more particles become correlated, it does not enable the transmission of information instantaneously.
The reason for this is that, even though the entangled particles may exhibit instantaneous correlations when measured, any information extracted from the entangled particles is subject to the limitations of the speed of light. Classical communication, which is necessary to complete the teleportation process, cannot occur faster than the speed of light.
Therefore, while quantum teleportation demonstrates the transfer of quantum states between qubits, it does not violate the principle that information cannot be transmitted faster than the speed of light.