PHILADELPHIA The field of metamaterials involves augmenting materials with specially designed patterns, enabling those materials to manipulate electromagnetic waves and fields in previously impossible ways. Now, researchers from the University of Pennsylvania have come up with a theory for moving this phenomenon onto the quantum scale, laying out blueprints for materials where electrons have nearly zero effective mass.
Such materials could make for faster circuits with novel properties.
The work was conducted by Nader Engheta, the H. Nedwill Ramsey Professor of Electrical and Systems Engineering in Penn's School of Engineering and Applied Science, and Mario G. Silveirinha, who was a visiting scholar at the Engineering School when their collaboration began. He is currently an associate professor at the University of Coimbra, Portugal.
Their paper was published in the journal Physical Review B: Rapid Communications.
Their idea was born out of the similarities and analogies between the mathematics that govern electromagnetic waves Maxwell's Equations and those that govern the quantum mechanics of electrons Schrdinger's Equations.
On the electromagnetic side, inspiration came from work the two researchers had done on metamaterials that manipulate permittivity, a trait of materials related to their reaction to electric fields. They theorized that, by alternating between thin layers of materials with positive and negative permittivity, they could construct a bulk metamaterial with an effective permittivity at or near zero. Critically, this property is only achieved when an electromagnetic wave passes through the layers head on, against the grain of the stack. This directional dependence, known as anisotropy, has practical applications.
The researchers saw parallels between this phenomenon and the electron transport behavior demonstrated in Leo Esaki's Nobel Prize-winning work on superlattices
|Contact: Evan Lerner|
University of Pennsylvania