Scientists at the University of Washington have made a groundbreaking discovery that could revolutionise the field of quantum technology. By observing the emitted light from atoms stimulated by a laser, the researchers successfully detected the mechanical vibration, or "breathing," between two layers of atoms. This newly discovered atomic phenomenon, known as phonons, has the potential to serve as a fundamental building block for encoding and transmitting quantum information.
The study, published in Nature Nanotechnology, highlights the development of a unique device utilizing the principles of "optomechanics." Optomechanics involves the intrinsic coupling of light and mechanical motions at the atomic scale. Lead author Adina Ripin, a doctoral student of physics at the university, explained that this discovery offers a novel platform for controlling single photons within integrated optical circuits, opening doors to various quantum applications. This discovery opens up new possibilities for harnessing atomic-scale phenomena and unlocking the transformative potential of quantum information processing and communication.
To create a single photon emitter, or "quantum emitter," the research team placed two layers of tungsten and selenium atoms, specifically tungsten diselenide, on top of each other. By applying a precise pulse of laser light, they generated a quasiparticle called an exciton, consisting of a negatively charged electron and a positively charged hole. As the electron dropped back into the hole, it emitted a single photon encoded with quantum information, fulfilling the researchers' objective.
During their investigation, the team unexpectedly detected another type of quasiparticle: phonons. Phonons, generated by atomic vibrations resembling breathing motions, were observed in the two-dimensional atomic system for the first time in a single photon emitter. Analysis of the emitted light spectrum revealed equally spaced peaks, indicating that every photon emitted by an exciton was coupled with one or more phonons.
Importantly, the researchers demonstrated that they could manipulate the interaction energy between phonons and emitted photons by applying electrical voltage. These controllable variations hold significant implications for encoding quantum information into single photon emissions. The experiments were conducted on a device consisting of only a small number of atoms, showcasing the potential for scalability.
Looking ahead, the team plans to construct a waveguide on a chip, enabling the collection and directed transmission of single photon emissions. By expanding their control to multiple emitters and their associated phonon states, the researchers aim to establish communication between quantum emitters. This milestone represents a crucial step towards building a solid foundation for quantum circuitry.
Professor Mo Li, senior author of the study and a faculty member in both electrical and computer engineering and physics at the University of Washington, emphasised the ultimate goal of creating an integrated system that utilizes quantum emitters, single photons, and phonons for quantum computing and sensing applications. He believes that this breakthrough will significantly contribute to the development of quantum computing and its future applications.