Synopsis: Connecting Qubits with Sound

Surface acoustic waves may work as a “quantum bus” that carries information to different parts of a quantum computer.

As quantum computers eventually become larger, they will need a way to connect distant qubits. Sound waves that skirt along a surface may provide a solution. A new theoretical analysis details how surface acoustic waves (SAWs) can be coupled to qubits embedded in a micrometer-scale acoustic cavity. Through this coupling, the SAWs can act as a “quantum bus,” relaying information over SAW waveguides.

Photons have been a natural choice for carrying quantum information, and recent experiments have connected two qubits with microwave photons inside a millimeter-long cavity. A possible alternative medium is acoustic phonons, which can potentially couple to qubits in chip-compatible cavities that are much smaller than those used for photons.

Previous work on phonon-qubit coupling has largely focused on phonons localized within cantilevers or similar resonators. Ignacio Cirac of the Max Planck Institute for Quantum Optics, Germany, and his colleagues explored the potential of SAWs. These surface-bound “ripples” can be confined in cavities by grooves that act like mirrors. And—unlike phonon modes in a cantilever—SAWs can travel long distances over surface-etched waveguides. To couple SAW phonons to a qubit, Cirac and his collaborators modeled a SAW cavity in which the surface material is piezoelectric. SAWs inside such a cavity would generate an oscillating electric field, which could interact with a nearby qubit—no matter what type it is. This “universality” implies that a qubit made from quantum dots, for example, could transfer its information to a SAW phonon, and this phonon could deliver the information to a distant qubit that might be a trapped atom or other type qubit.

This research is published in Physical Review X.

–Michael Schirber


Announcements

More Announcements »

Subject Areas

Quantum InformationAcoustics

Previous Synopsis

Quantum Information

How to Tame a Trojan Horse

Read More »

Next Synopsis

Related Articles

Viewpoint: Particles Move to the Beat of a Microfluidic Drum
Fluid Dynamics

Viewpoint: Particles Move to the Beat of a Microfluidic Drum

A thin vibrating plate can organize microscopic particles within a liquid into different patterns, an effect like that observed in 18th century studies of musical instruments. Read More »

Synopsis: One-Way Quantumness
Quantum Physics

Synopsis: One-Way Quantumness

Experiments provide evidence for one-way quantum steering—an effect by which distant entangled systems can influence one another in a directional way. Read More »

Viewpoint: Quantum Hoverboards on Superconducting Circuits
Quantum Physics

Viewpoint: Quantum Hoverboards on Superconducting Circuits

A new quantum device uses a superconducting circuit to monitor a 2D gas of electrons floating on the surface of superfluid helium. Read More »

More Articles