From Santa Barbara, California, to Hefei, China, scientists are developing a new type of computer that makes today’s machines look like toys.
Taking advantage of the mysterious powers of quantum mechanics, the technology will perform tasks in minutes that even supercomputers could not complete in thousands of years. Google in the fall of 2019 experimental quantum computer showed that it was possible. Two years later, a laboratory in China did almost the same.
But quantum computing will not reach its potential without the help of another technological breakthrough. Call it the “quantum internet,” a network of computers that can send quantum information between remote machines.
At Delft University of Technology in the Netherlands, a team of physicists has taken an important step towards this future computer network by using a technique called quantum teleportation to send data to three physical locations. It was possible before with only two.
The new experiment shows that scientists can spread a quantum network to more and more sites. “We’re currently building small quantum networks in the lab,” said Delft physicist Ronald Hanson, who oversaw the team. “But the idea is to finally build a quantum internet.”
Their research was announced this week. An article published in the scientific journal Natureillustrates the power of a phenomenon Albert Einstein once thought impossible. Quantum teleportation – what he calls “remote spooky action” — can transfer information between locations without actually moving the physical matter holding it.
This technology could profoundly change the way data travels from one place to another. It is based on more than a century of research involving quantum mechanics, a field of physics that governs the subatomic space and is unlike anything we experience in our daily lives. Quantum teleportation not only moves data between quantum computers, it does so in a way that no one can interfere with.
“This not only means that the quantum computer can solve your problem, it also means it doesn’t know what the problem is,” said Tracy Eleanor Northup, a researcher at the Institute for Experimental Physics at the University of Innsbruck and who also studies quantum teleportation. “It doesn’t work that way today. Google knows what you’re running on its servers.”
A quantum computer takes advantage of strange behavior patterns when certain objects are very small (like an electron or a particle of light) or very cold (like an exotic metal cooled to almost absolute zero or minus 460 degrees Fahrenheit). In these cases, a single object can act as two separate objects at the same time.
Conventional computers perform calculations by processing “bits” of information where each bit holds either a 1 or a 0. Taking advantage of the strange behavior of quantum mechanics, a quantum bit or qubit can store a combination of 1 and 0 – a bit like a spinning coin retains the probability of getting heads or tails when it finally lands on the table.
This means that two qubits can hold four values simultaneously, three qubits can hold eight, four can hold 16, and so on. It means. As the number of qubits increases, a quantum computer becomes exponentially more powerful.
Researchers hope these devices will one day enable the creation of new drugs, power advances in artificial intelligence, and Briefly break the encryption protecting computers vital to national security. Governments, academic labs, startups, and tech giants around the world spend billions of dollars exploring technology.
on Google in 2019 announced machine had achieved what scientists call “quantum superiority,” meaning it could perform an experimental task impossible with conventional computers. But most experts believe it will take a few more years – at least – before a quantum computer can do something useful that you can’t do with any other machine.
Part of the difficulty is breaking a qubit, or “dissolving the coherin” if you read information from it – it becomes an ordinary bit that can only hold 0 or 1, but not both. But scientists hope to make machines that are both powerful and practical by combining many qubits and developing ways to guard against mismatch.
Ultimately, ideally, these are combined into networks that can send information between nodes and allow them to be used from anywhere, just as cloud computing services like Google and Amazon make computing power widely available today.
But this comes with its own problems. Partly due to incompatibility, quantum information cannot simply be copied and sent over a conventional network. Quantum teleportation offers an alternative.
While it cannot move objects from one place to another, it can carry information by taking advantage of a quantum property called “entanglement”: A change in the state of one quantum system instantly affects the state of another at a distance.
Dr. “After entanglement, you can no longer identify these states individually,” Northup said. “Basically, it’s now a single system.”
These entangled systems can be electrons, particles of light, or other objects. In the Netherlands, Dr. Hanson and his team used what is called a nitrogen vacancy center – a small empty space inside a synthetic diamond where electrons can be trapped.
The team built three of these quantum systems, named Alice, Bob, and Charlie, and connected them in a line with strands of optical fiber. Scientists can then scramble these systems by sending individual photons—particles of light—between them.
First, the researchers entangled two electrons, one belonging to Alice and the other to Bob. In effect, electrons were given the same spin and thus combined or entangled in a common quantum state, each storing the same information: a particular combination of 1 and 0.
The researchers can then transfer this quantum state to another qubit, a carbon core inside Bob’s synthetic diamond. Doing so freed up Bob’s electron, and the researchers were then able to mistake it for another electron belonging to Charlie.
By performing a specific quantum operation on both Bob’s qubits (the electron and the carbon nucleus), the researchers were able to glue two entanglement together: Alice and Bob were glued to Bob and Charlie.
Result: Alice got confused with Charlie, who allowed the data to be teleported across all three nodes.
Data is not lost when it moves this way without traversing the distance between nodes. Dr. “Information can feed on one side of the link and then appear on the other,” Hanson said.
Information cannot be captured either. A future quantum internet powered by quantum teleportation could provide a new type of encryption that is theoretically unbreakable.
In the new experiment, the mesh nodes weren’t that far away—just about 60 feet. But previous experiments have shown that quantum systems can travel over longer distances.
The hope is that after a few more years of research, quantum teleportation will be viable for many miles. Dr. “We’re trying to do this outside of the lab now,” Hanson said.