Succeeding at greater distances will offer an affirmative solution to a thought experiment known as Bell’s theorem, proposed in 1964 by the Irish physicist John Stewart Bell as a method for determining whether particles connected via quantum entanglement communicate information faster than the speed of light.
“There is a big race going on between five or six groups to prove Einstein wrong,” said Ronald Hanson, a physicist who leads the group at Delft. “There is one very big fish.”
In the past, scientists have made halting gains in teleporting quantum information, a feat that is achieved by forcing physically separated quantum bits into an entangled state.
But reliability of quantum teleportation has been elusive. For example, in 2009, University of Maryland physicists demonstrated the transfer of quantum information, but only one of every 100 million attempts succeeded, meaning that transferring a single bit of quantum information required roughly 10 minutes.
In contrast, the scientists at Delft have achieved the ability “deterministically,” meaning they can now teleport the quantum state of two entangled electrons accurately 100 percent of the time.
They did so by producing qubits using electrons trapped in diamonds at extremely low temperatures. According to Dr. Hanson, the diamonds effectively create “miniprisons” in which the electrons were held. The researchers were able to establish a spin, or value, for electrons, and then read the value reliably.
In addition to the possibility of an impregnable quantum Internet, the research holds out the possibility of networks of quantum computers.
To date, practical quantum computers, which could solve certain classes of problems far more quickly than even the most powerful computers now in use, remain a distant goal. A functional quantum computer would need to entangle a large number of qubits and maintain that entangled state for relatively long periods, something that has so far not been achieved.
A distributed quantum network might also offer new forms of privacy, Dr. Hanson suggested. Such a network would make it possible for a remote user to perform a quantum calculation on a server, while at the same time making it impossible for the operator of the server to determine the nature of the calculation.
