Science fiction movies had told a different meaning of teleportation to us, even getting connected to the movies which are telling the meaning of teleportation can be true but not at the time we are living in because till the moment we are only teleporting the information from one place to other without any means but we need a classical channel to communicate to tell the other person to apply a particular gate to extract the original information without any deformation. Quantum teleportation is an example of quantum entanglement, it is completely due to entanglement between two particles so we can teleport the information. Quantum teleportation is being used as a method of communication in the field of quantum computing. When two particles are entangled with each other then they connect every information about each other and after when we want to teleport the particle, we will make some changes in the first particle then the second particle show some changes too which we measure and is known as quantum teleportation. The image of teleportation we have in our mind can’t be made true till now because to teleport a human being or a person it is required to teleport atoms from one place to any other because it’s been difficult to teleport a single photon from one place to another and we are talking to teleport this much number of atoms in a correct order to not place his/her eyes or ears at any other place whereas being on the right place. To make the teleportation true it will take a longer time not in next 2 to 3 decades.
Quantum Teleportation
Quantum teleportation is a process that transfers quantum information from a sender at one location to a receiver some distance away.
How to teleport an information? Generate an entangled pair of photons with spin states A and B, in a particular Bell state. Separate the entangled electrons, sending A to Alice and B to Bob. Alice measures the “Bell state” of A and C, entangling A and C. Alice sends the result of her measurement to Bob via some classical method of communication. Bob measures the spin of state B along an axis determined by Alice’s measurement. Quantum teleportation does not physically transfer particles between locations. The information in state C has been “teleported” to Bob’s state. The final spin state of B looks like C’s original state. The particles involved in teleportation never change between observers. Classical information needs to be sent from sender to receiver, so quantum teleportation cannot occur faster than the speed of light. Entangled particles play a crucial role in quantum teleportation, as they allow for the transfer of quantum information from one location to another without physical transport of the particles themselves.
Science behind Quantum Teleportation
The theoretical framework of quantum mechanics that enables quantum teleportation is based on the principles of entanglement and superposition. Here’s how it works:
Entanglement: Quantum mechanics allows for the existence of entangled particles, which are connected in such a way that the state of one particle is dependent on the state of the other, regardless of the distance between them.
Superposition: Quantum mechanics also allows for the existence of particles in a superposition of states, meaning that a particle can exist in multiple states simultaneously.
Quantum Circuit: The simplest quantum teleportation circuit requires only three qubits. Alice puts her qubit into a quantum superposition using a Hadamard gate, and then she entangles her qubit with Bob’s qubit using a controlled-NOT gate.
Measurement: Alice then takes a third qubit, which has the quantum state to be teleported, and she entangles that qubit with her qubit. She then measures her two qubits in two different bases, which destroys her quantum information but gives her the classical information she needs to provide to Bob.
Classical Communication: Alice sends the classical information to Bob, who uses it to perform operations on his qubit that then allows him to use the teleported quantum state for whatever purposes.
No-Cloning Theorem: Quantum teleportation does not violate the no-cloning theorem, which states that an arbitrary unknown quantum state cannot be copied exactly. The original state is destroyed during the teleportation process.
Quantum Channel: Quantum teleportation requires a quantum channel, which is a communication mechanism that is used for all quantum information transmission. In addition to the quantum channel, a traditional channel must also be used to accompany a qubit to “preserve” the quantum information.
No-Communication Theorem: Quantum teleportation cannot occur faster than the speed of light, as it requires classical communication to accompany the quantum information. This is known as the no-communication theorem.
Experiments and Breakthroughs First successful experiment of quantum teleportation was done by Anton Zeilinger in 1998, which involved entanglement swapping, or the teleportation of an entangled state. The Zeilinger group experimentally realized entanglement swapping, and it was later applied to carry out a delayed choice entanglement test. In 1998, Zeilinger’s group was the first to
implement quantum cryptography with entangled photons. Zeilinger is widely known for the first realization of quantum teleportation of an independent qubit. He later expanded this work to develop a source for freely propagating teleported qubits and quantum teleportation over 144 kilometers between two Canary Islands. Some of the list of the most recent advancements and experiments that have pushed the boundaries of quantum teleportation are:
Long-distance quantum teleportation: In 2023, researchers were able to teleport quantum information from a photon to a solid-state qubit over a distance of 1km using multiplexed quantum memories.
Quantum teleportation of multiple degrees of freedom: In 2015, scientists were able to teleport the quantum information from ensemble of rubidium atoms to another ensemble of rubidium atoms over a distance of 150 meters using entangled photons.
Quantum teleportation over long distances: In 2020, researchers achieved quantum teleportation over a total distance of 44 km with fidelities exceeding 90%.
Quantum teleportation of logical operations: In 2018, physicists demonstrated a deterministic teleported CNOT operation between logically encoded qubits.
Quantum teleportation using superconducting nanowire detectors: In 2015, researchers set a record for quantum teleportation over optical fiber at a distance of 102 km.
Applications and Implications
Quantum network: In 2016, a scientific team in China successfully achieved quantum teleportation in relatively long-range communication using the existing fibre network. Almost at the same time, the Canadian scientific team also achieved quantum teleportation independently for several kilometres using a slightly different with previous one. And China’s ‘first commercial quantum private communication network was built for national defence, finance and other aspects in 2017. Their success may serve as an important milestone in building an international quantum network in the real world.
Quantum computing system: In 2019, IBM revealed a quantum computing system named ‘IBM Q’ which is the first industrial-grade system built with integrated commercial universal quantum systems for business and science applications. It is a critical step towards the quantum computing system to break off from the lab. Quantum teleportation has many potential applications, including quantum computing, cryptography, and secure communication. It also raises interesting philosophical questions about the nature of space and time. Quantum teleportation has many potential implications, including revolutionizing quantum computing and secure communication.
Challenges and Limitations
For optimal quantum teleportation, there are many conditions that should be satisfied.
- There is no limitation for the input information.
- The input information and output can be supplied and verified by the third party except for the sender and receiver.
- A complete Bell measurement is achieved.
- Conditional unitary transmission could be performed before the verification from the third party.
- The fidelity of teleportation should be higher than the appropriate threshold of the classical protocol.
In many cases, only a few subsets of the Bell measurement are feasible and the feed-forward is either unaccomplished or simulated in post-processing, thus the conditions (3) and (4) are not satisfied generally.There are other issues to consider like the propagation losses of light and the atomic coherence lifetime raised from the classical protocol.
