Researchers from the University of Washington have made a significant discovery, finding that they can detect the atomic “breathing” phenomenon between layers of atoms by observing the emitted light when stimulated by a laser. This breakthrough has potential implications for encoding and transmitting quantum information. Additionally, the team has developed a novel device that could serve as a fundamental building block for various quantum technologies, expected to have wide-ranging applications in computing, communications, and sensor development.

Published in Nature Nanotechnology on June 1, the study unveils an atomic-scale platform utilizing the principles of “optomechanics” to couple light and mechanical motions. The researchers believe this innovative approach offers new possibilities to control single photons within integrated optical circuits, paving the way for numerous applications.

Previously, the team focused on studying an exciton, a quantum-level quasiparticle that can store and release information in the form of photons—the fundamental units of light. Quantum properties of these emitted photons, such as polarization, wavelength, and emission timing, act as quantum bits or “qubits” for quantum computing and communication. Since photons travel at the speed of light, they are an ideal choice for transmitting quantum information through optical fibers over long distances with minimal energy loss.

The researchers aimed to create a quantum emitter, capable of emitting single photons, as a critical component for light and optics-based quantum technologies. They achieved this by stacking thin layers of tungsten and selenium atoms, known as tungsten diselenide. When a precise laser pulse was applied, it displaced an electron from a tungsten diselenide atom, resulting in the creation of an exciton. Each exciton consisted of a negatively charged electron in one layer and a positively charged hole in the other, tightly bound together due to the attractive forces between opposite charges. As the electron dropped back into the hole, the exciton emitted a single photon encoded with quantum information, fulfilling the team’s objective of creating a quantum emitter.

However, during the experiment, the researchers discovered that the tungsten diselenide atoms emitted another quasiparticle known as a phonon, which is a product of atomic vibration similar to breathing. The two atomic layers acted like tiny vibrating drumheads, generating these phonons. This marks the first observation of phonons in a single photon emitter within a two-dimensional atomic system.

Upon analyzing the emitted light spectrum, the researchers observed equally spaced peaks. Each exciton-emitted photon was associated with one or more phonons, resulting in a ladder-like quantum energy spectrum represented by the spaced peaks.

To explore the potential of harnessing phonons for quantum technology, the researchers applied electrical voltage and successfully manipulated the interaction energy between the phonons and emitted photons. These measurable and controllable variations hold promise for encoding quantum information into single photon emissions within an integrated system consisting of only a few atoms.

Moving forward, the team aims to construct a waveguide—a fiber-based chip that can capture single photon emissions and direct them efficiently. Scaling up the system, they aspire to control multiple quantum emitters and their associated phonon states, enabling intercommunication between emitters—a crucial step toward establishing a solid foundation for quantum circuitry.

The ultimate objective is to create an integrated system featuring quantum emitters that utilize single photons running through optical circuits, coupled with the newly discovered phonons, for quantum computing and quantum sensing. This advancement significantly contributes to these efforts and further propels the development of quantum computing, which holds immense potential for future applications.

By Impact Lab