Scientists detect the breath between atoms

The discovery may lead to a new method of quantum computing.
Loukia Papadopoulos
An illustration of an array of single-photon emitters.jpg
An illustration of an array of single-photon emitters.

Ruoming Peng/University of Washington 

University of Washington researchers have detected the mechanical vibration between two layers of atoms (the atoms’ breaths) by observing the type of light those atoms emitted when stimulated by a laser. 

This is according to a press release published by the institution on Friday.

This new development could lead to a new method for quantum computing. In fact, the researchers have already engineered a device that could serve as a new type of building block for quantum technologies.

"This is a new, atomic-scale platform, using what the scientific community calls 'optomechanics,' in which light and mechanical motions are intrinsically coupled together," said senior author Mo Li, a UW professor of both electrical and computer engineering and physics. 

"It provides a new type of involved quantum effect that can be utilized to control single photons running through integrated optical circuits for many applications."

The new study builds on previous work that examined a quantum-level quasiparticle called an "exciton." Information can be encoded into an exciton and then released in the form of a photon whose quantum properties can function as a quantum bit of information, or "qubit," at the speed of light.

A bird's-eye view

"The bird's-eye view of this research is that to feasibly have a quantum network, we need to have ways of reliably creating, operating on, storing and transmitting qubits," said lead author Adina Ripin, a UW doctoral student of physics. 

"Photons are a natural choice for transmitting this quantum information because optical fibers enable us to transport photons long distances at high speeds, with low losses of energy or information."

Next, the researchers decided to test if they could harness phonons for quantum technology using electrical voltage. They found that they could vary the interaction energy of the associated phonons in measurable and controllable ways and in one single integrated system.

Next the team wanted to be able to control multiple emitters and their associated phonon states, a step toward building a solid base for quantum circuitry.

"Our overarching goal is to create an integrated system with quantum emitters that can use single photons running through optical circuits and the newly discovered phonons to do quantum computing and quantum sensing," Li said in the statement.

"This advance certainly will contribute to that effort, and it helps to further develop quantum computing which, in the future, will have many applications."

The study is published in Nature Nanotechnology.

Study abstract:

Engineering the coupling between fundamental quantum excitations is at the heart of quantum science and technologies. An outstanding case is the creation of quantum light sources in which coupling between single photons and phonons can be controlled and harnessed to enable quantum information transduction. Here we report the deterministic creation of quantum emitters featuring highly tunable coupling between excitons and phonons. The quantum emitters are formed in strain-induced quantum dots created in homobilayer WSe2. The colocalization of quantum-confined interlayer excitons and terahertz interlayer breathing-mode phonons, which directly modulates the exciton energy, leads to a uniquely strong phonon coupling to single-photon emission, with a Huang–Rhys factor reaching up to 6.3. The single-photon spectrum of interlayer exciton emission features a single-photon purity >83% and multiple phonon replicas, each heralding the creation of a phonon Fock state in the quantum emitter. Due to the vertical dipole moment of the interlayer exciton, the phonon–photon interaction is electrically tunable to be higher than the exciton and phonon decoherence rate, and hence promises to reach the strong-coupling regime. Our result demonstrates a solid-state quantum excitonic–optomechanical system at the atomic interface of the WSe2 bilayer that emits flying photonic qubits coupled with stationary phonons, which could be exploited for quantum transduction and interconnection.