Quantum teleportation is an important step to improve quantum computing.
“Beam me up” is one of the most famous phrases in the Star Trek series. It is the command issued when a character wishes to teleport from a remote location back to the Enterprise spacecraft.
While human teleportation only exists in science fiction, teleportation is possible in the subatomic world of quantum mechanics, although not in the way it is normally portrayed on television. In the quantum world, teleportation involves the transport of information, rather than the transport of matter.
Last year, scientists confirmed that information could pass between photons on computer chips even when the photons were not physically linked.
Now, according to new research from the University of Rochester and Purdue University, teleportation may also be possible between electrons.
A quantum processor semiconductor chip is connected to a circuit board in the laboratory of John Nichol, an assistant professor of physics at the University of Rochester. Nichol and Andrew Jordan, a professor of physics, are exploring new ways to create quantum-mechanical interactions between distant electrons, promising breakthroughs in quantum computing. Credit: University of Rochester photo / J. Adam Fenster
In an article published in Nature’s Communications and one to appear in Physical Review XThe researchers, including John Nichol, an assistant professor of physics at Rochester, and Andrew Jordan, a professor of physics at Rochester, explore new ways to create quantum-mechanical interactions between distant electrons. Research is an important step in improving quantum computing, which, in turn, has the potential to revolutionize technology, medicine, and science by providing faster and more efficient processors and sensors.
‘Creepy action at a distance’
Quantum teleportation is a demonstration of what Albert Einstein called “spooky action at a distance,” also known as quantum entanglement. When entangled, one of the basic concepts of quantum physics, the properties of one particle affect the properties of another, even when the particles are separated by a great distance. Quantum teleportation involves two distant, entangled particles in which the state of a third particle instantly “teleports” its state to the two entangled particles.
Quantum teleportation is an important means of transmitting information in quantum computing. While a typical computer consists of billions of transistors, called bits, quantum computers encode information in quantum bits, or qubits. A bit has a single binary value, which can be “0” or “1”, but qubits can be both “0” and “1” at the same time. The ability of individual qubits to simultaneously occupy multiple states underlies the great potential power of quantum computers.
Scientists have recently demonstrated quantum teleportation by using electromagnetic photons to create remotely entangled pairs of qubits.
However, Qubits made of individual electrons also hold promise for transmitting information in semiconductors.
“The single electrons are promising qubits because they interact very easily with each other, and the single electron qubits in semiconductors are also scalable,” says Nichol. “Reliably creating long-distance interactions between electrons is essential for quantum computing.”
However, creating entangled pairs of electron qubits spanning long distances, which is necessary for teleportation, has proven challenging: Although photons naturally propagate over long distances, electrons are generally confined to one location.
Tangled electron pairs
To demonstrate quantum teleportation using electrons, the researchers used a recently developed technique based on the principles of Heisenberg’s exchange coupling. An individual electron is like a bar magnet with a north pole and a south pole that can point up or down. The direction of the pole, whether the north pole points up or down, for example, is known as the magnetic moment of the electron or the state of quantum gyration. If certain types of particles have the same magnetic moment, they cannot be in the same place at the same time. That is, two electrons in the same quantum state cannot sit on top of each other. If they did, their states would shift back and forth in time.
The researchers used the technique to distribute tangled electron pairs and teleport their spin states.
“We provide evidence of ‘tangle exchange,’ in which we create entanglement between two electrons even though the particles never interact, and ‘quantum gate teleportation,’ a potentially useful technique for quantum computing by teleportation,” says Nichol. “Our work shows that this can be done even without photons.”
The results pave the way for future research on quantum teleportation involving spin states of all matter, not just photons, and provide further evidence of the surprisingly useful capabilities of individual electrons in qubit semiconductors.
References
“Conditional teleportation of spin states of quantum dots” by Haifeng Qiao, Yadav P. Kandel, Sreenath K. Manikandan, Andrew N. Jordan, Saeed Fallahi, Geoffrey C. Gardner, Michael J. Manfra and John M. Nichol, 15 June 2020, Nature’s Communications.
DOI: 10.1038 / s41467-020-16745-0
“Coherent Exchange of Multiple Spins in a Quantum Dot Spin Chain” by Haifeng Qiao, Yadav P. Kandel, Kuangyin Deng, Saeed Fallahi, Geoffrey C. Gardner, Michael J. Manfra, Edwin Barnes, John M. Nichol, accepted on May 12, 2020 Physical Review X.
arXiv: 2001.02277
