Another day, another exciting quantum computing advancement
The existence of parafermions, which are grouped electrons that behave as liquids in a special state of matter, may have just given the quantum computing field a boost in coherence and error prevention. Scientists from Singapore's Nanyang Technical University(opens in new tab) have demonstrated experimental results that they believe will lead to parafermions when electrons are kept at temperatures close to absolute zero (-273 degrees Celsius). Scientists had only thought that electrons could have strong interactions, but the study proved that they can when certain conditions are met. This was a big step forward.
Electricity is produced by the ordered movement of electrons. Even when electrons are moving in this "ordered" pattern, they are not. Because electrons are negatively charged, they repel one another and tend to move in random directions (like a gas) rather than as a cohesive whole. They're similar to drunk drivers in that they may arrive at their destination with a few "bumps" along the way. But when electrons act like liquids, it's like replacing drunk drivers with orderly ones who know and respect each other's boundaries, speed, and direction to avoid accidents and get to their destinations faster.
There has been a lot of theoretical speculation about these types of drivers, but now we know for sure that strong electron interactions do happen.
When electrons are made to act in a "helical Tomonaga-Luttinger liquid," there are fewer particle interactions and energy exchanges between them and the system. This reduces the amount of systemic and environmental interference, which is frequently the source of errors and collapsed quantum states in quantum systems. The electrons' previously being cooled to near absolute zero is also an important factor, as it allows certain materials to achieve the state of a superconductor, in which electrons traverse their surface without any electrical resistance, reducing the possibility of environmental interference. When a system is cooled to absolute zero (4.5 Kelvin or -269 degrees Celsius in the experiment), particles slow down to the point where they are almost immobile.
Electrons (and their spin properties) have long been used as quantum-programmable particles. Improvements in electron control that result in fewer disturbances result in fewer errors and improved coherence, resulting in a longer life for the actual qubits that can store or process information. In fact, superconducting qubits are already used in some quantum systems (such as IBM's Quantum One and Quantum Two).
In this case, scientists used an atom-thick graphene substrate to deposit atom-thick crystals of tungsten ditelluride, an almost two-dimensional material known as a "quantum spin Hall insulator" that insulates gravity on the inside while containing electrons on the outside. The graphene/tungsten ditelluride substrate was assembled and cooled to absolute zero before being examined under a scanning tunneling microscope at one nanometer from its surface: smaller than a DNA strand and smaller than any transistor ever manufactured (even when looking at the ones powering the latest and greatest graphics cards).
Researchers found that when electrons in a graphene/tungsten substrate were put under a scanning tunneling microscope and cooled to absolute zero, they moved away from each other more. Because of the interaction between each electron's repulsion field, their repulsion was so strong that the electrons were forced to move collectively. The researchers recorded a Luttinger parameter between 0.21 and 0.33. This parameter represents the strength of particle interactions; when it reaches 1, the interactions are the weakest.
"When the Luttinger parameter is less than 0.5, the electrons are forced into collective motion and the interactions are strong." "This is the realm where parafermions are expected to exist," explained Assistant Prof. Weber. "Because the Luttinger parameter can only be between 0 and 1," he continued, "this is a truly remarkable range of variation." "The Luttinger parameter has never been able to be controlled at such low values in any helical Tomonaga-Luttinger liquid before."
The team is now planning to lower temperatures even further by utilizing NTU Singapore's newly built Ultra-Low Vibration Laboratory, which was completed earlier this year. The laboratory will enable researchers to conduct experiments at even lower temperatures of 150 millikelvins (mK)—even closer to absolute zero—allowing them to observe stronger electron repulsion and the actual witnessing of parafermion groupings.
Surprisingly, the researchers' approach seems to be related to Microsoft's own race to implement so-called topological qubits and their required (but still non-working) Majorana modes.
