Xingjie Ni

Professor Xingjie Ni came to Penn State in August 2015 after working on an invisibility cloak at University of California-Berkeley.

It's not quite the invisibility cloak that Harry Potter dons in “Harry Potter and the Philosopher’s Stone,” but researchers are working on making that cloak a reality.

One of those researchers is Xingjie Ni, Penn State assistant professor of electrical engineering.

Ni came to Penn State in August 2015, and while at the University of California-Berkeley, Ni worked with a team of researchers on developing an invisibility cloak.

In order to make the invisibility cloak happen, researchers must have a detailed knowledge of light waves, metamaterials and nanostructures.

However, there are certain limitations when it comes to the cloak. The pyramid-shaped cloak has a tiny antennae on the surface, and with each object, the antennae must be adjusted properly in order to make the small object underneath the cloak appear invisible, Adrian Cho, staff writer for Science Magazine, said.

“Essentially what they’ve done is taken this antennae technique and figured out a way to apply it to light,” Cho said. “Then they can make it look like the light wave just reflected off the surface instead of hitting the object.”

Ni doesn't focus specifically on the invisibility cloak anymore, but rather looks at using similar characteristics of the invisibility cloak and applies them to different elements.

"It's like you have this route, which is your knowledge on the light-meta interaction in a nanoscale. Then we try to have this applied in different things, so this cloak is just one application," Ni said.

Though still in its early stages, the process of developing the invisibility cloak has numerous issues. When Ni conducts his research, there is a three-step protocol to determining if a solution has been discovered.

For Ni, there are three stages to conducting experiments: the first stage is about coming up with a theory that supports the original idea; the next step focuses on the design portion and actually constructing the design; and the final step is to calculate whether or not this theory can work and oftentimes it takes more than one try, Ni said.

“Basically you make the design and make the device and you do the test, then you see ‘Oh, it’s not working.’ So we go back to see if there is a problem in the design or if it is a problem in the fabrication,” Ni said.

The future and growth of the invisibility cloak is also difficult to determine. With such an advanced level of science needed to continue making improvements, it is difficult for researchers to determine where the invisibility cloak is headed.

“There are a lot of problems in terms of making it broadband so that you would cover all wave lengths that you'd be interested in covering,” David Smith, department chair of computer engineering and director of the center for metamaterials and integrated plasmonics at Duke University, said. “The requirements to have a functioning invisibility cloak are probably beyond even what we can foresee right now."

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