A major step towards reliable processing of quantum information

Bright minds around the world are developing quantum technology. One of the main challenges is controlling and reading qubits reliably. Canadian researchers are taking a big step in the right direction by developing a new optical system.

The exceptionally powerful method by which green laser light is split into extremely small beams of light and focused on individual barium ions is an important milestone on the road to an efficient quantum computer in the near future. The new machine Developed By a Canadian team University of Waterloo It uses a small glass waveguide to separate the laser beams. In the end, there are only four microns between the different rays of green light focused on the atomic particles. This equates to a distance 25 times smaller than the thickness of a human hair. The precision and scale with which all the lasers are focused simultaneously on their qubit targets is unparalleled.

“Talk” to ions
“Our design means that only 0.01 percent of the laser light falls on a neighboring ion. This is a very low percentage. It is one of the best results compared to other quantum research anywhere in the world,” says researcher Rajib Islam.

“Other methods that have tried to control individual ions have had problems, but our modifiers do not affect each other. This means that we can ‘talk’ to any ion without disturbing its neighbors. This is known to be the most flexible ion qubit control system in the world. It has the highest accuracy among all systems developed in the academic and industrial world.

Green laser
The researchers focused on barium ions, which have become increasingly popular among quantum scientists. They have very useful energy states that can be used as 0 and 1 values ​​for a qubit. Barium ions also respond to visible green light, eliminating the need for high-energy ultraviolet light.

Many other types of atoms require ultraviolet light to achieve the same processing. For example, researchers can use commercially available optical techniques. Like a green laser. These possibilities do not exist for ultraviolet wavelengths.

Natural qubits
Researchers have developed a waveguide chip that converts a single laser beam into sixteen different light channels. Each channel is then sent to an individual optical modulator, which can adjust the intensity, frequency and phase of the lasers independently of other modulators. Next, a series of optical lenses, similar to a telescope, are used to magnify individual barium ions.

“This work is part of our mission to… University of Waterloo “To build barium ion quantum processors using atomic systems,” said researcher Crystal Sinko. “We use ions because they are identical natural qubits. We don’t have to make them, our job is to find ways to control them.

What is a qubit?
A qubit, also called qbit or quantum bit, is a unit of quantum information that can be thought of as a quantum mechanical version of the classical data bit. Qubits use the quantum mechanical phenomenon of superposition to obtain a linear combination of two states. A classical binary bit can represent only one binary value, 0 or 1, which means it can have only one of two possible states. However, a qubit can represent 0, 1, or any part of 0 and 1 in a superposition of both cases. There is a certain probability of 0 and a certain probability of 1. This superposition gives quantum computers superior computing power. The amount of data that a qubit system can process is increasing dramatically. It would take a classical computer millions of years to find the prime factors of a 2048-bit number. Qubits can perform calculations in just a few minutes.