A research team led by University of Bristol scientists has successfully demonstrated quantum teleportation of information between two programmable micrometer-scale silicon chips. The team’s work, published in the journal Nature Physics, lays the groundwork for large-scale integrated photonic quantum technologies for communications and computations.

Quantum teleportation offers quantum state transfer of a quantum particle from one place to another by utilizing entanglement.

Teleportation is not only useful for quantum communication but is a fundamental building-block of optical quantum computing.

Establishing an entangled communication link between two chips in the lab however has proven to be highly challenging.

“We were able to demonstrate a high-quality entanglement link across two chips in the lab, where photons on either chip share a single quantum state,” said study first author Dr. Dan Llewellyn, a researcher in the Quantum Engineering Technology Labs at the University of Bristol.

“Each chip was then fully programmed to perform a range of demonstrations which utilize the entanglement.”

“The flagship demonstration was a two-chip teleportation experiment, whereby the individual quantum state of a particle is transmitted across the two chips after a quantum measurement is performed.”

“This measurement utilizes the strange behavior of quantum physics, which simultaneously collapses the entanglement link and transfers the particle state to another particle already on the receiver chip.”

“Based on our previous result of on-chip high quality single-photon sources, we have built an even more complex circuit containing four sources,” added study co-author Dr. Imad Faruque, also from the Quantum Engineering Technology Labs at the University of Bristol.

“All of these sources are tested and found to be nearly identical emitting nearly identical photons, which is an essential criterion for the set of experiments we had performed, such as entanglement swapping.”

The results showed extremely high-fidelity quantum teleportation of 91%.

In addition, the team was able to demonstrate some other important functionality of their designs, such as entanglement swapping (required for quantum repeaters and quantum networks) and four-photon GHZ states (required in quantum computing and the quantum internet).

“Low loss, high stability, and excellent controllability are extremely important for integrated quantum photonics,” said study co-author Dr. Yunhong Ding, a researcher in the Department of Photonics Engineering and the Center for Silicon Photonics for Optical Communication at Technical University of Denmark.

“In the future, a single silicon-chip integration of quantum photonic devices and classical electronic controls will open the door for fully chip-based CMOS-compatible quantum communication and information processing networks,” said Dr. Jianwei Wang, a scientist at Peking University and corresponding author of the study.

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D. Llewellyn et al. Chip-to-chip quantum teleportation and multi-photon entanglement in silicon. Nat. Phys, published online December 23, 2019; doi: 10.1038/s41567-019-0727-x