Our publications

New quantum behaviours in one dimension

Swinburne researchers have discovered unexpected and entirely new quantum behaviors that only occur in one-dimensional systems, such as electrical current, in a new paper published in Physical Review Letters.

The paper explores a fundamental question in quantum physics: what happens when a single "impurity" particle, such as an atom or electron, is introduced into a tightly packed crowd of identical particles. See also the media report by Phys Org.

Realizing the Einstein-Podolsky-Rosen paradox for atomic clouds

A viewpoint article by Margaret Reid was published in the American Physical Society's journal Physics examining the implications of a recent experiment realizing the Einstein-Podolsy-Rosen paradox for atomic clouds.

Finding all the Feynman diagrams for the Fermi polaron problem

Polaron has been a very active topic in solid-state physics and atomic physics. This study provides a general and exact theory to determine finite-temperature quasiparticle properties of Fermi polarons, which is important for the current exploration of polaron physics in cold-atom research and in condensed matter physics.

Interestingly, their work presents a very rare case that a quantum many-body system can be exactly solved by working out the complete Feynman diagrams. This non-trivial case may inspire future developments of more accurate diagrammatic theories of strongly correlated Fermi systems.

Simulating Gaussian boson sampling quantum computers

A growing cohort of experimental linear photonic networks implementing Gaussian boson sampling (GBS) have now claimed quantum advantage. However, many open questions remain on how to effectively verify these experimental results, as scalable methods are needed that fully capture the rich array of quantum correlations generated by these photonic quantum computers.

This article reviews recent theoretical methods to simulate experimental GBS networks with a focus on methods using phase-space representations of quantum mechanics. A brief overview of the theory of GBS, recent experiments, and other types of methods are also presented.

Quantum central limit theorems, emergence of classicality and time-dependent differential entropy

The Central Limit Theorem (CLT) is a cornerstone of statistics, serving as a powerful tool for making inferences about populations based on sample data. It states that even if a population does not have a normal distribution, the means of many samples drawn from it will form a normally distributed population under some general and mild conditions.

In the quantum domain, Professor Tien Kieu has now derived a Quantum Central Limit Theorem (QCLT) which serves as a powerful tool for understanding macroscopic behaviours of quantum systems. It provides a pathway for classical behaviours to emerge in the bulk from the random behaviour of quantum systems.

Exact many-body solution for Fermi polarons

The behaviour of an impurity immersed in a Fermi sea – the so-called Fermi polaron – is a long-standing problem in condensed matter physics. Over the last 15 years, due to the unprecedented controllability, there are great efforts from ultracold atom community to quantitatively understand Fermi polaron.

Our researchers have proposed an exact solvable model of Fermi polarons in the heavy impurity limit and solved it by using a novel functional determinant approach (FDA). The key ingredient is the superfluid pairing gap of the many-body background, which strongly suppresses the multiple particle-hole excitations in the background BCS superfluid as the pair-breaking will cost energy.

Second sound attentuation near quantum criticality

In collaboration with USTC Shanghai, we contribute to observing the second sound attentuation of a unitary Fermi gas near the superfluid transition. Various quantum transport coefficients, such as shear viscosity and thermal conductivity, have been determined with unprecedented accuracy.

This work accomplishes a quantitative experimental examination of the dissipative two-fluid hydrodynamic theory in the unitary Fermi gas and paves a new way for determining the universal critical scaling functions in the strongly interacting regime.