Tiny sound waves could help solve a major quantum computing problem

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have demonstrated a new way to protect delicate quantum information using mechanical vibrations, essentially microscopic sound waves.

The advance, developed in the lab of Marko Lončar, Tiantsai Lin Professor of Electrical Engineering, could support the development of compact quantum networks built directly onto chips. It may also help enable hybrid quantum systems that combine several different kinds of quantum bits, or qubits.

The findings are published in Nature Physics. The experiments were led by Eliza Cornell, a recent Ph.D. graduate from the Lončar lab who is now a postdoctoral researcher at Boston University, and Zhujing Xu, a former postdoctoral scholar in Lončar's group.

Using Sound to Carry Quantum Information

One promising approach to quantum networking uses the spin of an electron, associated with impurity in diamond, to store quantum information. Tiny packets of mechanical vibration called phonons can then serve as carriers that move information between qubit nodes.

The Lončar lab has played a major role in exploring the potential of these systems. Among its advances is a structure known as a phononic cavity, which traps mechanical vibrations so they can interact more strongly with the electron spin inside a qubit.