In a groundbreaking use of teleportation, critical units of a quantum processor have been successfully distributed across multiple computers, proving the potential of distributing quantum modules without compromising their performance.
Although the transfer only took place over a two-meter (about six feet) space in a University of Oxford lab, the leap was more than enough to underscore the feasibility of scaling quantum technology by teleporting quantum states across an “internet” of connected systems.
Teleportation is a quirk of physics that only makes sense through a quantum lens, where objects exist in a blur of possible characteristics until measurement processes force them into each state.
By mixing the undecided states of different objects in an act known as entanglement, and then carefully choosing the right kinds of measurements to make on one of them, it is possible to use the responses to force an entangled object some distance away to adopt (and destroy) the quantum identity of the original object.
It may not be the kind of teleportation that would transport passengers across the vacuum of space in the blink of an eye, but it’s perfect for sharing the blur of information needed for logical operations on a quantum processor.
“Previous demonstrations of quantum teleportation have focused on the transfer of quantum states between physically separate systems,” says lead author Dougal Main, a physicist at the University of Oxford.
“In our study, we use quantum teleportation to create interactions between these distant systems.”
While classical computers use binary ‘on or off’ switches to perform sequences of calculations on bits of information, quantum computers use mathematically complex distributions of possibilities known as qubits, typically represented in a simple feature of an uncharged particle, such as a charged atom.
To make this process practical, hundreds or even thousands of these particles need to have their not-yet-decided states entangled with each other in a restricted way, without intrusive objects interfering with their own possibilities and messing up the calculations.
Scaling current technology to that level is complicated by hurdles that require error correction or shielding processes to preserve the delicate quantum states long enough for them to be measured.
Linking multiple smaller processors together in a network to create a kind of quantum supercomputer is another solution. While quantum information can be transmitted in the form of a light wave, the potential for its state to be irreversibly corrupted along the way makes this an impractical option.
Teleportation requires receiving measurements the old-fashioned way—via reliable binary data. Once sent, operations on the receiving end can tweak their own entangled particle until it effectively resembles the original.
The all-important quantum blur of the teleported spin state in the Oxford University experiment was an 86 percent match to the original, more than good enough to serve as a logic gate for a simple operation known as Grover’s algorithm, which succeeded with 71 percent efficiency on both quantum processors.
“By interconnecting modules using photonic links, our system gains valuable flexibility, allowing modules to be upgraded or swapped without disrupting the entire architecture,” says Main
Having options for reengineering a quantum network could diversify the applications of this technology, repurposing computer networks into tools that can measure and test physics at its most fundamental level.
This research is published in Nature .
