Atomic “Breathing” – A New Building Block for Quantum Technology

 

International Conference on Nuclear Physics


Researchers at the University of Washington have detected atomic “breathing,” or mechanical vibration between atom layers, which could help encode and transmit quantum information. They also created an integrated device that manipulates these atomic vibrations and light emissions, advancing quantum technology development.




Scientists at the University of Washington have found a way to detect atomic “breathing,” the mechanical oscillation between two atomic layers, by watching the specific light these atoms radiate when excited by a laser. The sound of this atomic “breathing” could assist researchers in encoding and delivering quantum data.


The researchers also developed a device that could serve as a new type of building block for quantum technologies, which are widely anticipated to have many future applications in fields such as computing, communications, and sensor development.



Previously, the team had studied a quantum-level quasiparticle called an “exciton.” Information can be encoded into an exciton and then released in the form of a photon — a tiny particle of energy considered to be the quantum unit of light. Quantum properties of each photon emitted — such as the photon’s polarization, wavelength, and/or emission timing — can function as a quantum bit of information, or “qubit,” for quantum computing and communication. And because this qubit is carried by a photon, it travels at the speed of light.


“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.”


The researchers were working with excitons in order to create a single photon emitter, or “quantum emitter,” which is a critical component for quantum technologies based on light and optics. To do this, the team placed two thin layers of tungsten and selenium atoms, known as tungsten diselenide, on top of each other.


When the researchers applied a precise pulse of laser light, they knocked a tungsten diselenide atom’s electron away from the nucleus, which generated an exciton quasiparticle. Each exciton consisted of a negatively charged electron on one layer of the tungsten diselenide and a positively charged hole where the electron used to be on the other layer. And because opposite charges attract each other, the electron and the hole in each exciton were tightly bonded to each other. After a short moment, as the electron dropped back into the hole it previously occupied, the exciton emitted a single photon encoded with quantum information — producing the quantum emitter the team sought to create.


But the team discovered that the tungsten diselenide atoms were emitting another type of quasiparticle, known as a phonon. Phonons are a product of atomic vibration, which is similar to breathing. Here, the two atomic layers of the tungsten diselenide acted like tiny drumheads vibrating relative to each other, which generated phonons. This is the first time phonons have ever been observed in a single photon emitter in this type of two-dimensional atomic system.



When the researchers measured the spectrum of the emitted light, they noticed several equally spaced peaks. Every single photon emitted by an exciton was coupled with one or more phonons. This is somewhat akin to climbing a quantum energy ladder one rung at a time, and on the spectrum, these energy spikes were represented visually by the equally spaced peaks.


The researchers were curious if they could harness the phonons for quantum technology. They applied electrical voltage and saw that they could vary the interaction energy of the associated phonons and emitted photons. These variations were measurable and controllable in ways relevant to encoding quantum information into a single photon emission. And this was all accomplished in one integrated system — a device that involved only a small number of atoms.


#AtomicStructure#AtomicTheory#AtomicPhysics#AtomicNucleus#AtomicParticles
#AtomicEnergy#AtomicBonding#AtomicMass#AtomicNumber#AtomicSpectroscopy
#AtomicAbsorption#AtomicEmission



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