Physicists in China claim to have teleported the quantum states of photons nearly 100 km in free space, breaking the previous record by a factor of 100. The development could pave the way for satellite-based quantum communication, or fundamental tests of quantum mechanics over long distances.
Quantum teleportation is a way of transferring a quantum state from one place to another without actually sending a particle in that state through space. In the normal arrangement, two people, Alice and Bob, each take one half of a pair of entangled particles and then go their separate ways. Whenever Alice wants to send a quantum state to Bob, she allows a third particle in that state to interact with her half of the entangled pair of particles.
Alice then sends the result of a measurement on the system to Bob using a conventional (non-quantum) means of communication. Bob uses this information to modify his half of the entangled pair such that it is in a quantum state identical to the state that Alice wanted to send. This occurs despite the fact that Alice never actually sent a particle in that state. Another bizarre outcome of the process is that although the original copy of Alice’s state is destroyed by her measurement, Bob can be made to reappear nearly 100 km away.
Quantum teleportation is a process by which quantum information (e.g. the exact state of an atom or photon) can be transmitted (exactly in principle) from one location to another, with the help of classical communication and previously shared quantum entanglement between the sending and receiving location. Because it depends on classical communication, which can proceed no faster than the speed of light, it cannot be used for superluminal transport or communication. And because it disrupts the quantum system at the sending location, it cannot be used to violate the no-cloning theorem by producing two copies of the system. Quantum teleportation is unrelated to the kind of teleportation commonly used in fiction, as it does not transport the system itself, does not function instantaneously, and does not concern rearranging particles to copy the form of an object. Thus, despite the provocative name, it is best thought of as a kind of communication, rather than a kind of transportation.
How to spot Neptune in the night sky on Aug. 24
Binoculars or a small telescope is all skygazers will need to spot the tiny blue-green disk in the night sky.
hey guys let me know how this goes. it will invariably be raining tomorrow as it always is when there is a stargazing event.