Quantum Teleportation? Researchers Develop Photonic Chips that Encode Quantum Information in CircuitsJanuary 01, 2020 by Tyler Charboneau
Recently, scientists have successfully paired quantum particle technology with nano-scale circuitry.
Quantum computing has been a buzzword in the industry for some time, and for good reason. Quantum physics is said to make massive inroads in solving complex problems that even supercomputers can't accomplish.
The internal schematic of a quantum-enabled chipset. Black lines: single-mode waveguides for the single photons; red and blue pulses: photon energy in each path. Yellow bars: external phase control. Image (modified) used courtesy of the University of Bristol and arXiv, Cornell University
Quantum particles are notoriously difficult to manipulate and encode. Recently, however, scientists from the University of Bristol and the Technical University of Denmark have successfully paired this technology with nano-scale circuitry.
This development, which the researchers have called "high-fidelity quantum teleportation," has ignited heightened interest in quantum technology.
But why does it matter?
The Basics of Quantum Teleportation
Quantum teleportation is often considered the key to quantum computing. Teleportation is the movement of quantum particles from one place to the next through entanglement. This phenomenon relies on containing quantum particles in proximity to one another, making them interdependent.
This can even occur over larger distances when two particles are spaced apart. When these particles are entangled, a change in even one particle can affect the entire system.
(Left) "Scanning electron microscope (SEM) images of an MRR single-photon source coupled to a bus-waveguide"; (Right) "Metasurface-assisted low-loss subwavelength grating couplers (SGC) with bonded aluminium reflectors." Image (modified) used courtesy of the University of Bristol and arXiv, Cornell University
Teleportation comes into play when we contain entangled systems within two chips. The key is designing a system that allows particles to move between these chips, thus transmitting information. Scientists at the University of Bristol refer to this as “entanglement swapping.”
These controlled collapses transfer the state of one particle to another. In Bristol's breakthrough experiment, the entanglement link simultaneously collapses and transfers the particle state to another particle already on the receiver chip.
Silicon Carbide Chips and Quantum Photonic Devices
Dr. Jianwei Wang, a lead author of the group’s piece in the journal Nature Physics, believes silicon carbide chips are exceptional testbeds. These chips allow researchers to fuse classical electronic controls with quantum photonic devices.
Silicon carbide can emit single photons at a wavelength near the telecommunications band, according to Professor David Awschalom, a professor in molecular engineering at UChicago and a pioneer in quantum technology. This unlocks long-distance communications potential using current fiber optic networks.
Photons are a central pillar of quantum technologies. These particles are particularly adept at sharing quantum states as part of a system. Quantum information is stored in these systems, meaning particle displacement promotes inter-chip communication. Furthermore, this transfer of information is extremely efficient at a 91% success rate.
Fidelities for the teleported states and GHZ entangled states. Image (modified) used courtesy of the University of Bristol and arXiv, Cornell University
We can also fine-tune these compounds to lessen wave fluctuation. These observations could have developmental implications for future data networks.
Implications for Future Technologies
In the past, quantum electronics have used materials like diamonds and precious metals for optimal stability. We now know that existing hardware can support new advancements.
A team at the University of Chicago has accomplished just that. These scientists have uncovered a way to integrate quantum “bits” into everyday electronic devices, through quantum control. The experiment at the University of Chicago brings us one step closer to creating quantum-enhanced phones, laptops, and even vehicles.
University of Chicago graduate students observe quantum experiments at the Pritzker School of Molecular Engineering. Image used courtesy of David Awschalom and UChicago News
These improvements come at a time when chip architecture is becoming increasingly complex. Despite the progress in supercomputers, these systems are beginning to show their limitations with hyper-complex tasks. Quantum processing will make it much easier to future-proof these systems.
According to Dr. Yunhong Ding of the Technical University of Denmark, this processing model relies upon “low loss, high stability, and excellent controllability."
Because researchers have found that 3-dimensional qutrit teleportation achieves notably-higher fidelity than classical transportation, these quantum chips, and networks for that matter, will be much better at transmitting complex information no matter the application.
Scheme (from "Quantum Teleportation in High Dimensions") for teleportation of three-dimensional quantum states if person A ("Alice") holds a quantum state encoded in three dimensions that she plans to teleport to person B ("Bob"). Image used courtesy of University of Science and Technology of China, the University of Vienna, and arXiv, Cornell University
The Next Step
The research published by the University of Bristol and the Technical University of Denmark marks significant progress in quantum networks with entanglement swapping and in quantum computing and quantum internet with their findings on four-photon GHZ states.
The leading authors of the research, however, have ambitious plans for extending their study of quantum teleportation in the future.
Dr. Wang (now at Peking University) explained, “In the future, a single Si-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.”