Temperature evolution of impurities in a quantum gas – ScienceDaily

Quantum Pollution Theory investigates the behavior of intentionally introduced atoms (ie “impurities”) that behave as particularly “clean” quasiparticles in an atomic background gas, thus enabling a controllable “perfect test environment” for quantum correlations.

The study extends quantum impurity theory, which is of great interest to the quantum matter research community, into a new dimension – the thermal effect.

“We discovered a general relationship between two different experimental protocols, namely ejection and injection radio frequency spectroscopy, for which no such relationship was known prior to our work,” explains lead author Dr. Weizhe Liu (Faculty of Physics and Astronomy at Monash University).

QUANTUM IMPURITY THEORY

Quantum impurity theory studies the effects of introducing atoms of one element (i.e., “impurities”) into an ultra-cold atomic gas of another element.

For example, a small number of potassium atoms can be introduced into a “background” quantum gas of lithium atoms.

The introduced impurities (in this case the potassium atoms) behave like a particularly “clean” quasiparticle in the atomic gas.

Interactions between the introduced impurity atoms and the atomic background gas can be “tuned” via an external magnetic field, whereby quantum correlations can be investigated.

In recent years there has been an explosion of studies on the subject of quantum impurities, which, thanks to their controllable realization in ultra-cold atomic gases, have been immersed in various background media.

MODELING ‘PUSH’ AND ‘PULL’ WITH RADIO FREQUENCY PULSES

“Our study is based on high frequency spectroscopy and models two different scenarios: ejection and injection,” says Dr. Weizhe Liu, research associate at FLEET, FLEET in the group of A / Prof Meera Parish and Dr. Jesper Levinsen.

The team modeled the effect of high-frequency pulses that would force impurity atoms from one spin state to another, unoccupied spin state.

• In the “ejection” scenario, high frequency pulses act on impurities in a spin state that interact strongly with the background medium and “push” these impurities into a non-interacting spin state.
• The inverse “injection” scenario “pulls” contaminants from a non-interacting state to an interacting state.

These two spectroscopies are commonly used separately to study different aspects of the quantum pollution problem.

* Instead, the new Monash study shows that the ejection and injection logs check the same information.

“We found that the two scenarios – ejection and injection – are linked by an exponential function of the difference in free energy between the interacting and non-interacting impurity states,” says Dr. Liu.