We deal with bits and bytes every day, whether it’s sending text messages or receiving emails.
There are also quantum bits, or qubits, which differ dramatically from ordinary bits and bytes. These photons – particles of light – can carry quantum information and provide extraordinary energy that cannot be obtained otherwise. Unlike binary numbers, where bits can only represent 0 or 1, qubits behave in a mechanical way. Because of the “heading up”, a qubit can represent a 0, a 1, or anything in between.
This increases the processing speed of quantum computers compared to existing computers. “Learning the potential of qubits has been a catalyst for the development of quantum technology, opening up new and undiscovered applications such as quantum communication, computing and understanding,” said Hong Koo Kim, professor of electrical engineering at computer science at the University of Pittsburgh Swanson School of Engineering.
Quantum technology is important for many areas, from banks storing financial information to providing researchers with tools to model all aspects of chemistry. And thanks to quantum ‘entanglement’, qubits can ‘communicate’ over long distances as a single system. Kim and his graduate student, Yu Shi, have discovered something that could help quantum technology advance. It starts with a single photon
Photon-based quantum technology relies on a single photon source that can emit individual photons.
These single photons can be produced by nanoscale semiconductors, commonly called quantum dots. In the same way that a microwave antenna transmits a cell phone signal, a quantum dot acts as an antenna that transmits light.
“Through rigorous research, we found that the quantum dot emitter – or nanoscale dipole antenna – traps a lot of energy,” Kim explained. “The outdoor activity of the emitter dipole is understood, but this is really the first time that the dipole has been studied indoors.”
The images from these quantum dots appear sideways, as we can be right or left handed. Numerical information is carried by these individual photon emissions. Therefore, organizing them in different ways is an important task for quantum information processing.
Kim’s team has come up with a new way to separate photons from different molecules and bring them back together for further processing down the road. “The results of this work should contribute to the development of high-quality photon sources, which is an important prerequisite for quantum photonics,” Kim said.
The paper, “Spin Texture and Chiral Coupling of the Circularly Polarized Dipole Field,” was published in the journal Nanophotonics. The Office of Naval Research is supporting this project.
Source: University of Pittsburgh
