Furusawa group at the University of Tokyo has succeeded in demonstrating complete quantum teleportation of photonic quantum bits by a hybrid technique for the first time worldwide. In 1997, quantum teleportation of photonic quantum bits was achieved by a research team at Innsbruck University in Austria. However, such quantum teleportation couldn't be used for information processing, because measurement was required after transport, and the transport efficiency was low. So, quantum teleportation was still a long way from practical use in quantum communication and quantum computing.
The demonstration of quantum teleportation of photonic quantum bits by Furusawa group shows that transport efficiency can be over 100 times higher than before. Also, because no measurement is needed after transport, this result constitutes a major advance toward quantum information processing technology.
"In 1997, quantum bit teleportation was successfully achieved, but as I said just now, it was only achieved in a probabilistic sense. In 1998, we used a slightly different method to succeed at unconditional, complete teleportation. But at that time, the state sent wasn't a quantum bit, but something different. Now, we've used our experimental technology, which was successful in 1998, to achieve teleportation with quantum bits. The title of our paper is "Hybrid Technique," and developing that technique is where we've been successful."
The hybrid technique was developed by combining technology for transporting light waves with a broad frequency range, and technology for reducing the frequency range of photonic quantum bits. This has made it possible to incorporate photonic quantum bit information into light waves without disruption by noise. This research result has been published in Nature, and is attracting attention worldwide, as a step toward quantum information processing technology.
"I think we can definitely say that quantum computers have come closer to reality. Teleportation can be thought of as a quantum gate where input and output are the same. So, it's known that, if we improve this a little, the input and output could be produced in different forms. If changing the form of input and output like that is considered as a program, you have a programmable quantum gate. So, I think a quantum computer could be achieved by combining lots of those."
Looking ahead, Furusawa group aims to increase the transport efficiency and make the device smaller by using photonic chips. In this way, the researchers plan to achieve further advances toward quantum computing.