Attosecond science is undoubtedly one of the fastest growing branches of physics today.

Its popularity was demonstrated by the award of the 2023 Nobel Prize in Physics to Anne L’Huillier, Paul Corkum and Ferenc Krausz for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter.

One of the most important processes in this field is dephasing. This happens when an electron loses its phase coherence because of interactions with its surroundings.

This loss of coherence can obscure the fine details of electron dynamics, making it harder to capture precise snapshots of these rapid processes.

The most common way to model this process in light-matter interactions is by using the relaxation time approximation. This approach greatly simplifies the picture as it avoids the need to model every single particle in the system.

Its use is fine for dilute gases, but it doesn’t work as well with intense lasers and denser materials, such as solids, because it greatly overestimates ionisation.

This is a significant problem as ionisation is the first step in many processes such as electron acceleration and high-harmonic generation.

To address this problem, a team led by researchers from the University of Ottawa have developed a new method to correct for this problem.

By introducing a heat bath into the model they were able to represent the many-body environment that interacts with electrons, without significantly increasing the complexity.

This new approach should enable the identification of new effects in attosecond science or wherever strong electromagnetic fields interact with matter.

The post Studying the role of the quantum environment in attosecond science appeared first on Physics World.

Describing the non-classical properties of a complex many-body system (such as entanglement or coherence) is an important part of quantum technologies.

An ideal tool for this task would work well with large systems, be easily computable and easily measurable. Unfortunately, such a tool for every situation does not yet exist.

With this goal in mind a team of researchers – Marcin Płodzień and Maciej Lewenstein (ICFO, Barcelona, Spain) and Jan Chwedeńczuk (University of Warsaw, Poland) – began work on a special type of quantum state used in quantum computing – graph states.

These states can be visualised as graphs or networks where each vertex represents a qubit, and each edge represents an interaction between pairs of qubits.

The team studied four different shapes of graph states using new mathematical tools they developed. They found that one of these in particular, the Turán graph, could be very useful in quantum metrology.

Their method is (relatively) straightforward and does not require many assumptions. This means that it could be applied to any shape of graph beyond the four studied here.

The results will be useful in various quantum technologies wherever precise knowledge of many-body quantum correlations is necessary.

The post Characterising quantum many-body states appeared first on Physics World.