ICFO develops QUIONE, quantum simulator that observes individual atoms…

24 Apr 2024

…and Toshiba-Single Quantum collaboration doubles range of secure QKD communications.

Quantum physics needs high-precision sensing techniques to delve deeper into the properties of materials. From the analog quantum processors that have emerged recently, the so-called quantum-gas microscopes have proven to be powerful tools for understanding quantum systems at the atomic level.

Now, researchers from ICFO, Barcelona, Spain, have built their own quantum-gas microscope, named QUIONE after the Greek goddess of snow. The group – Sandra Buob, Jonatan Höschele, Vasiliy Makhalov and Antonio Rubio-Abadal, led by ICREA Professor at ICFO Leticia Tarruell – explains how their microscope is the only one imaging individual atoms of strontium quantum gases in the world, as well as the first of its kind in Spain.

Beyond the significant images, in which individual atoms can be distinguished, the goal of QUIONE is quantum simulation. As ICREA Prof. Leticia Tarruell explained, “Quantum simulation can be used to boil down very complicated systems into simpler models to then understand open questions that current computers cannot answer, such as why some materials conduct electricity without any losses even at relatively high temperatures.”

The singularity of this experiment lies in the fact that they have managed to bring the strontium gas to the quantum regime, place it in an optical lattice where the atoms could interact by collisions and then apply the single atom imaging techniques. These elements altogether make ICFO’s strontium quantum-gas microscope unique in its kind.

Why strontium?

Until now, these microscope setups relied on alkaline atoms, such as lithium and potassium, which have simpler properties in terms of their optical spectrum compared to alkaline-earth atoms such as strontium.

In recent years, the properties of strontium have made it a popular element for applications in the fields of quantum computing and quantum simulation. For example, a cloud of strontium atoms can be used as an atomic quantum processor, which could solve problems beyond the capabilities of current classical computers.

QUIONE, a quantum simulator of real crystals

The team first lowered the temperature of the strontium gas. Using the force of several laser beams, the speed of atoms can be reduced to a point where they remain almost motionless, reducing their temperature to almost absolute zero in just a few milliseconds. At that point, the atoms display new behavior like quantum superposition and entanglement.

After that, with the help of dedicated lasers, the researchers activate the optical lattice, which keeps the atoms arranged in a grid along space. “You can imagine it like an egg carton, where the individual sites are actually where you put the eggs. But we have atoms and the optical lattice,” said Sandra Buob, first author of the article.

The atoms in the egg cup interact with each other, sometimes exhibiting quantum tunneling to move from one place to another. Such “quantum dynamics” between atoms mimics that of tunneling in certain materials. Therefore, the study of these systems can help understand the complex behavior of certain materials, which is the key idea of quantum simulation.

Toshiba collaboration doubles range of QKD communications

Toshiba Europe and Single Quantum B.V. have collaborated to test and validate long-distance deployments of Quantum Key Distribution (QKD) technology.

Following extended validation testing of Toshiba’s QKD technology and Single Quantum’s superconducting nanowire single photon detectors (SNSPDs), the partners have announced a solution that substantially extends the transmission range for QKD deployment over fiber connections – up to and beyond 300km.

QKD uses the quantum properties of light to generate quantum secure keys that are immune to decryption by both high-performance conventional and quantum computers. Toshiba’s QKD is deployed over fiber networks, either coexisting with conventional data transmissions on deployed “lit” fibers, or on dedicated quantum fibers.

Toshiba’s QKD technology can deliver quantum secure keys in a single fiber optic link at distances of up to 150km using standard integrated semiconductor devices. Achieving longer distance QKD transmission is challenging due to the attenuation of the quantum signals along the fiber length. To provide extended QKD transmission, operators typically concatenate links together.

“Forward-thinking organizations are already deploying QKD on networks to protect their data from the risk posed by quantum computers,” said Dr Andrew Shields, Head of the Toshiba Quantum Technology Division.