“Beam me up” (“Transport me”) is one of the most famous catchphrases in the film and TV series Star Trek. It is the command issued when a character wishes to teleport from a remote location to the Enterprise ship.
Human teleportation exists only in science fiction. But the phenomenon is possible in the subatomic world of quantum mechanics – although not in the way normally described on TV. In the quantum world, teleportation involves the transport of information, not matter.
In 2019, scientists confirmed that information could be passed between photons on computer chips, even when the photons were not physically connected. Now, according to new research from the University of Rochester and Purdue University (USA), teleportation may also be possible between electrons.
In an article published in the magazine “Nature Communications”And another published in“ Physical Review X ”, the researchers, led by Haifeng Qiao and Yadav Kandel, from the University of 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.
Ghostly action at a distance
Quantum teleportation is a demonstration of what Albert Einstein called “ghostly action at a distance” – also known as quantum entanglement. In entanglement (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 the qubits can be “0” and “1” at the same time. The ability of individual qubits to occupy several states simultaneously underlies the great potential power of quantum computers.
Scientists recently demonstrated quantum teleportation using electromagnetic photons to create matched pairs of qubits remotely.
Qubits made of individual electrons, however, are also promising for the transmission of information in semiconductors.
“Individual electrons are promising qubits because they interact very easily with each other, and individual electron qubits in semiconductors are also scalable,” says John Nichol, assistant professor of physics at the University of Rochester and co-author of the study. “The reliable creation of long-distance interactions between electrons is essential for quantum computing.”
The creation of entangled pairs of electron qubits that span long distances, which is necessary for teleportation, proved to be a challenge: although photons naturally propagate over long distances, electrons are usually confined in a single location.
Tangled pairs of electrons
To demonstrate quantum teleportation using electrons, the researchers used a newly 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 is pointing up or down, for example – is known as the electron’s magnetic moment or state of quantum rotation. 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 be on top of each other. If they did, their states would alternate in time.
The researchers used the technique to distribute entangled pairs of electrons and teleport their states of rotation (spin).
“We provide evidence for ‘entanglement exchange’, in which we create entanglement between two electrons, even if the particles never interact, and ‘quantum gate teleportation’, a potentially useful technique for quantum computing using teleportation,” says Nichol. “Our work shows that this can be done even without photons.”
The results pave the way for research on quantum teleportation involving spin states of all matter, not just photons, and provide further evidence for the surprisingly useful capacities of individual electrons in qubit semiconductors.