Chinese researchers say they have demonstrated quantum teleportation under novel conditions, in an achievement that could have significant implications for the advancement of quantum communication technologies.
The breakthrough, reported by researchers at Shanxi University in China, involves a successful demonstration of simultaneous teleportation with multiple sideband qumodes—light-based carriers of quantum information that potentially offer a promising alternative to discrete qubits, which are currently viewed as the “gold standard” in quantum computation.
Having once been a longstanding obstacle to the technical realization of quantum teleportation, the successful transport of multiple qumodes in a continuous-variable system could signal a major leap in entanglement-based quantum communication capabilities in the years ahead.
Quantum Teleportation in the 21st-Century
While it may sound like science fiction, in the world of quantum communication, teleportation is very real. Unlike its fictional counterpart, where large objects—and even entire human bodies—are capable of instantaneous travel across sometimes vast distances, quantum teleportation involves the transfer of information, rather than matter, which is carried from one location to another by exploiting the phenomenon in physics known as entanglement.
The combined use of entanglement with otherwise normal classical information has enabled researchers to achieve quantum teleportation in the past, typically involving only a single sideband qumode in continuous-variable experiments. Such conditions rely on measurements of field amplitude and phase—known as quadratures—which assume a continuous range of values, making them ideal for applications requiring high-precision data collection.
This is important because it differs from the normal communication technologies we rely on daily, which send communications in parallel—think of a telephone, which collects audio from the voices of callers through a transmitter (or microphone) and delivers it to each handset’s receiver (or earpiece).
By contrast, quantum teleportation transfers information on a turn-for-turn basis, and achieving it across multiple channels—similar to everyday communication systems—has remained challenging.
A Quantum Communication Breakthrough
Now, according to a team led by Shanxi University researcher Xiaolong Su, the successful transmission of information, along with built-in controls, has been achieved, allowing them to demonstrate what they call “deterministic continuous-variable quantum teleportation” using several sideband qumodes simultaneously.
Their method relies on carefully tuned phases across a pair of classical communication channels in a system with adjustable frequency settings. This, they say, allowed the team to leverage phase-control capabilities to achieve teleportation with as many as five sideband qumodes within a 24 MHz bandwidth.
By using this phase-tuning method, the team also says they were able to select how many qumodes were teleported in each demonstration, enabling an additional level of control over the setup, rather than being restricted to a fixed number of qumodes that were successfully teleported.
Passing the Non-Cloning Limit
In addition to the variable controls they achieved, the team also reports attaining teleportation outputs with fidelities of nearly 70%.
Significantly, the Chinese research team says that all instances they observed exceeded the non-cloning limit, a threshold that sets an upper bound on the fidelity of copies, as outlined in the related concept known as the no-cloning theorem. This benchmark is often used as a boundary point for gauging bona fide quantum teleportation, as opposed to that which could feasibly be reproduced using purely classical methods.
Fundamentally, the team’s achievement demonstrates the teleportation of multiple sideband quantum states in parallel—itself a notable first—but also that the amount of sideband qumodes that can be teleported all at once is adjustable, with a little assistance from the phase of a classical channel.
“The results present a novel method for quantum teleportation of multiple quantum states simultaneously and take a crucial step in enhancing the teleporting ability of quantum teleportation,” the team writes.
The recent study, “Controllable deterministic quantum teleportation of multiple sideband qumodes,” was published in Science Bulletin.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.