Teleportation is no longer just science fiction—at the quantum level

Sixty years ago, Star Trek introduced what would become one of the most iconic science fiction technologies of all time: the transporter, a machine that could teleport a person from one place to another in an instant. Born out of the show’s need to save money rendering ship landings, the technology that could “beam” to and from the Enterprise became a hallmark of the show.

The Star Trek transporter converts matter into an energy stream, which is sent to a destination where the original matter is reconstructed, atom by atom. While Star Trek wasn’t the first work of fiction to depict teleportation, the transporter ignited the public’s imagination like nothing before it, producing enduring cultural memes and countless copycat technologies.

Then, teleportation became a real thing.

More than 30 years ago, a group of physicists needed a name for a radical new idea they’d come up with for how to transfer the quantum states of atoms or subatomic particles to other, distant particles without ever physically interacting with them. A quantum state is a mathematical concept representing information about an atom or subatomic particle—for instance, the energy level of an electron or the polarization of a photon.

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Inspired by science fiction, they landed on “quantum teleportation.” Since then, the idea has gone from theoretical concept to an experimentally verified reality. The first experiments in the late 1990s showed that quantum states could be transmitted across short distances, while subsequent research proved it works across increasingly longer distances—even to and from low Earth orbit, as Chinese scientists demonstrated in 2017. They’ve achieved quantum teleportation by taking advantage of quantum entanglement, a natural phenomenon in which tiny particles can become linked with each other across infinite distances.

Quantum teleportation is very different from the teleportation of matter we see in fiction. It involves transferring a quantum state without moving any matter. And while experts say it won’t lead to Star Trek-esque beaming, it could help bring about a new era of computing that revolutionizes our understanding of the subatomic world—and by extension, of the nature of the universe and everything within it.

“Fundamentally, nature is quantum,” says Jason Orcutt, a principal research scientist at IBM Quantum. “You are quantum information.”

Quantum teleportation could help solve complex problems

In everyday life, objects appear to obey a familiar set of rules known as classical physics. But shrink down to the level of atoms and subatomic particles, and a mind-boggling new rulebook takes over. This is the realm of quantum physics, where particles can exist in multiple states at once until measured and objects can become linked across infinite distances.

Much about the quantum world defies intuition—and description by normal computers. While everyday computers store and process “bits” of data encoded as 0s or 1s, the state of a quantum system does not always boil down to a simple binary. A different way of encoding data is needed, which is where quantum information, or qubits, come in.

While bits only ever represent a 0 or a 1, qubits can blend zero and one in quantum state until measured—a phenomenon known as superposition. Qubits can also become entangled with other qubits, so that measuring one instantly affects how another will be measured. The result is a complex form of information that underpins the power of quantum computing.

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“There are problems that are very hard, age of the universe hard, that we will not be able to solve with classical computing,” Orcutt says. But quantum computers may one day be able to simulate the molecular world, including complex chemical reactions, with remarkable accuracy. This could allow us to design better industrial processes—for instance, more energy-efficient ways to produce synthetic nitrogen for agriculture—or revolutionary new materials. 

Commercial quantum computers already exist, but their abilities are limited. Part of the work of building bigger and better ones—in particular, large-scale computers able to reliably correct errors and run very long computations—involves devising efficient ways to transfer quantum information. But there’s a problem: When you measure a quantum state “you alter it,” says Simone Portalupi, a quantum communications researcher and member of QR.N, a program aiming to extend the range of quantum communications. “So you can’t really clone quantum information.”

Different ways of sharing information are required, which is where quantum teleportation comes in. As a protocol for transferring quantum states from place to place without moving any matter, teleportation could become a standard way to communicate quantum information, allowing us to link together distant computers and one day build a quantum internet.

How quantum teleportation works

Entanglement is a natural phenomenon, but it can also be created artificially. And once two quantum systems are entangled, their state depends on each other no matter how far apart they are moved. This is why entanglement can be used to transmit information.

The classic example of how this works involves two researchers, Alice and Bob, who share an entangled pair of particles. In this scenario, Alice wants to send new information to Bob. She prepares a data qubit containing that information, then measures the data qubit and her half of the entangled particle pair at the same time. Known as a Bell-state measurement, this brings the data qubit into a state of entanglement with the other two, while at the same time revealing which of four states the two qubits in Alice’s possession share.  At the same time it destroys the original data qubit. (More on why in a bit.)

Alice’s measurement projects the information from the destroyed data qubit, along with her half of the entangled pair, as classical information—zeroes and ones. She then texts those results to Bob along a traditional communication channel.

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This classical communication step is crucial, says University of Calgary quantum information scientist Daniel Oblak, who likens it to instructions for how to open a box of snow globes so they are in the proper orientation. “To make it really a snow globe, you have to rotate it to be the right way up,” he says.

Alice’s measurement tells Bob what quantum operation to apply to his half of the entangled pair—which is essentially what allows him to “open the box” containing his half of the entangled pair. The result? Bob’s qubit is now in exactly the same state as Alice’s original data qubit. The information has been transferred.

The procedure for teleporting quantum states was first laid out in a paper published in 1993, followed by a series of experimental demonstrations. By the 2010s, scientists had figured out how to teleport various types of quantum states, including the states of superconducting circuits. Scientists have further shown that quantum states can be teleported between cities, and from Earth to space and back.

Today, Orcutt says, the field is moving “beyond science and into the engineering” needed to connect and scale up quantum computers.

But could this technology ever teleport a person?

While quantum teleportation may be essential for future quantum computers, experts say it is unlikely to lead to a device that can beam people on and off a spaceship.

“Comparing to Star Trek is hard,” says Tim Strobel, a Ph.D. student studying quantum communications and member of the QR.N project. “For us, it’s [teleporting] quantum states, not matter or energy.”

Oblak concedes that if you wanted to teleport a person from one place to another, you would need to transfer all the quantum information about the atoms and particles that make them up. You would also need “a pile of atoms that is ready to build a human in the other location [and] have the quantum state individually transferred into each of these bazillions of atoms,” he says. “It’s far out to imagine that is ever possible.”

There’s also the longstanding philosophical debate about beaming: Is the person who materializes out of thin air actually the same person, or a copy?

In quantum mechanics, the "no cloning" theorem states that it’s impossible to copy an unknown quantum state. Teleportation gets around this by measuring and destroying the original quantum state before it is teleported. Thus, on a quantum level, the teleported state is arguably the “same” one, rather than a copy.

If it turns out that what makes you who you are—your memories, personality, and even sense of self—boils down to quantum information, then perhaps you could teleport yourself to a new location. But if that’s not the case, you may simply be killing yourself so that your clone can live on elsewhere.

“That's all built entirely on speculation,” Orcutt says. “For now, the question of whether you can teleport a human, let alone an atom, exists squarely within the realm of science fiction—and so does any answer to that question.”