Programmable optical chip merges photons to change color

Cornell researchers have built a programmable optical chip that can change the color of light by merging photons, without requiring a new chip for new colors.

This form of nonlinear photonics could potentially be used for classical and quantum communications networks, all-optical signal processing and computation, spectroscopy and sensing.

“Previously, for each combination of colors you wanted to produce, you needed to fabricate a new device with a different design,” said Peter McMahon, associate professor of applied and engineering physics in Cornell Engineering, who led the project. “We now have a sort of universal device that lets you do any conversions you want, reprogrammably.”

The findings were published Oct. 8 in Nature. The paper’s first author is Ryotatsu Yanagimoto, a former postdoctoral researcher in the McMahon Lab and visiting scientist from NTT Research.

Read the full story in the Cornell Chronicle.

‘Bottling’ human intuition for AI-led materials discovery

Many properties of the world’s most advanced materials are beyond the reach of quantitative modeling. Understanding them also requires a human expert’s reasoning and intuition, which can’t be replicated by even the most powerful artificial intelligence, mixed with fortuitous accident, according to Eun-Ah Kim, the Hans A. Bethe Professor of physics in the College of Arts and Sciences and director of the Cornell-led National Science Foundation AI-Materials Institute. 

Kim and collaborators have developed a machine-learning model that encapsulates and quantifies the valuable intuition of human experts in the quest to discover new quantum materials. The model, Materials Expert-Artificial Intelligence (ME-AI), “bottles” this intuition into descriptors that predict the functional property of a material. The team used the method to solve a quantum materials problem.

Read the full story in the Cornell Chronicle.

Cornell–IBM collaboration advances quantum computing

The quantum computing revolution draws ever nearer, but the need for a computer that makes correctable errors continues to hold it back.

Through a collaboration with IBM led by Cornell, researchers have brought that revolution one step closer, achieving two major breakthroughs. First, they demonstrated an error-resistant implementation of universal quantum gates, the essential building blocks of quantum computation. Second, they showcased the power of a topological quantum computer in solving hard problems that a conventional computer couldn’t manage.

An international collaboration between researchers at IBM, Cornell, Harvard University and the Weizman Institute of Science demonstrated, for the first time, the ability to encode information by braiding – moving in a particular order – Fibonacci string net condensate (Fib SNC) anyons, which are exotic quasi-particles, in two dimensional space.

Read the full story in the Cornell Chronicle.