Quantum Simulator Discovers the Hidden Phase Change at Last!

Researchers have finally observed a series of atoms undergoing a one-dimensional phase transition that has been so difficult to detect that it likely could only occur within a quantum simulator after years of searching.

“One of the motivations [for our experiment] is truly about deciphering fundamental physics. We are attempting to comprehend merely the basic states that matter can exist in,” states Alexander Schuckert from the University of Maryland.

He and his team utilized electromagnetic fields to align 23 ions of the element ytterbium into a straight line, which formed a nearly one-dimensional arrangement. While this apparatus could be applied for quantum computing, the researchers chose to use the arrangement as a simulator for this purpose.

Inside, they constructed a one-dimensional ytterbium magnet by placing atoms one after another. Earlier predictions indicated that this type of magnet would lose its magnetism when heated due to quantum phenomena. However, no earlier experiment had accomplished this phase transition.

One challenge is that systems like quantum computers and simulators usually perform optimally at very low temperatures. In fact, raising their temperature to induce the phase transition can lead to malfunctions, Schuckert explains.

To circumvent this issue, he and his colleagues adjusted the initial quantum state of the atoms so that over time, the collective state of the one-dimensional magnet evolved as if its temperature had been increased. This elucidated the previously unobserved phase transition.

The accomplishment is quite unusual because arrays of atoms generally are not expected to experience phase transitions, remarks Mohammad Maghrebi from Michigan State University. The researchers could only produce this phenomenon because they managed to enable each ion to interact with others that were distant, even without direct contact. This induced the entire line to exhibit an unexpected collective behavior.

Since their simulator allows for such strange states of matter to manifest, it could serve to investigate theoretical systems that may be incredibly rare – or even non-existent – in nature, asserts Maghrebi.

Schuckert indicates that quantum simulators might also assist in elucidating peculiar electrical or magnetic behaviors displayed by certain materials in reality. However, to achieve this, these instruments need to attain higher temperatures than their current capabilities. They currently can simulate extremely low temperature scenarios only, yet he anticipates that higher-temperature simulations could be achievable within the next five years.

Furthermore, more existing and theoretical scenarios could be examined if the simulators were expanded, such as by arranging the ions into two-dimensional configurations, suggests Andrea Trombettoni from the University of Trieste in Italy. “This will introduce new physics to investigate,” he notes.