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Topics: Computer Engineering, Quantum Computing, Quantum Teleportation, Star Trek

For the first time, researchers have teleported a qutrit, a tripartite unit of quantum information. The independent results from two teams are an important advance for the field of quantum teleportation, which has long been limited to qubits—units of quantum information akin to the binary “bits” used in classical computing.

These proof-of-concept experiments demonstrate that qutrits, which can carry more information and have greater resistance to noise than qubits, may be used in future quantum networks.

Chinese physicist Guang-Can Guo and his colleagues at the University of Science and Technology of China (USTC) reported their results in a preprint paper on April 28, although that work remains to be published in a peer-reviewed journal. On June 24 the other team, an international collaboration headed by Anton Zeilinger of the Austrian Academy of Sciences and Jian-Wei Pan of USTC, reported its results in a preprint paper that has been accepted for publication in Physical Review Letters. That close timing—as well as the significance of the result—has each team vying for credit and making critiques of the other’s work.

The name quantum teleportation brings to mind a technology out of Star Trek, where “transporters” can “beam” macroscale objects—even living humans—between far-distant points in space. Reality is less glamorous. In quantum teleportation, the states of two entangled particles are what is transported—for instance, the spin of an electron. Even when far apart, entangled particles share a mysterious connection; in the case of two entangled electrons, whatever happens to one’s spin influences that of the other, instantaneously.

“Qutrit” Experiments Are a First in Quantum Teleportation, Daniel Garisto, Scientific American

Copper free: two Münster researchers compare a prototype optical chip to a one-cent coin. (Courtesy: University of Münster)

Topics: Artificial Intelligence, Computer Engineering, Neuromorphic Devices

A prototype artificial neural network (ANN) that uses only light to function has been unveiled by researchers at the University of Münster in Germany and the University of Exeter and University of Oxford in the UK. Their system can learn how to recognize simple patterns and its all-optical design could someday be exploited to create ANNs that can process large amounts of information rapidly while consuming relatively small amounts of energy.

ANNs mimic the human brain by using artificial neurons and synapses. A neuron receives one or more input signals and then uses this information to decide whether to output its own signal to the network. Synapses are the connections between neurons and can be “weighted” to favor signal propagation between certain neurons. An ANN can be trained to perform a task such as recognizing a pattern by sending multiple examples of the target pattern through the ANN while tweaking the synaptic weights until all examples of the target pattern elicit the same output from the ANN.

Relatively simple ANNs can be implemented on a computer. However, the conventional computer architecture of having a separate processor and memory makes it very difficult to implement the large numbers of neurons and synapses required to perform practical tasks.

One alternative is to create an ANN in which signals flows in the form of light pulses through an optical network. This is attractive because unlike electronic signals in a silicon chip, large amounts of light-encoded data can move quickly through optical materials without generating much heat. Furthermore, large amounts of information can be sent through an optical system by multiplexing the data using several different colors of light.

All-optical network mimics the brain’s neurons and synapses
Hamish Johnston, Physics World

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