Novel thermal phases of topological quantum matter in the lab

April 17, 2018

For the first time in the lab, a group of researchers from Universidad Complutense de Madrid, IBM, ETH Zurich, MIT and Harvard University have observed topological phases of matter of quantum states under the action of temperature or certain types of experimental imperfections. The experiment has been carried out in a platform of superconducting qubits at IBM, also known as quantum simulator.

Quantum simulators were first conjectured by the Nobel Prize in Physics, Richard Feynman, in 1982 since ordinary classical computers that we use nowadays were proved to be inefficient to simulate systems of interacting quantum particles.

These new simulators are genuinely quantum and can be controlled very precisely (for instance, systems of cold atoms trapped with lasers, or superconducting materials coupled to microwave radiation). They replicate other quantum systems that are harder to manipulate and whose physical properties remain very much unknown.

In an article published in the journal Quantum Information of the Nature Publishing Group, these researchers explain how using a quantum simulator with superconducting qubits at IBM, they were able to replicate materials known as topological insulators at finite temperature, and measure for the first time their topological quantum phases.

Topological phase of matter represent a very exciting and active field of research that is revolutionising our understanding of nature and material science. The study of these novel phases of matter has given rise to new materials such as topological insulators, which behave as regular insulators in the bulk and as metals at the boundaries. These boundary electronic currents have the spin (intrinsic magnetic moment) polarised, thus they are expected to play a very important role in spintronics, a novel alternative to conventional electronic technology.

Thermal topological phases

Since the discovery of topological matter, researchers have looked for innovative ways to maintain their properties at finite temperature. Previous theoretical works of the researchers at Universidad Complutense proposed a new topologial quantum phase, known as Uhmann phase, to characterise these phases of matter in thermal systems. The Uhlmann phase allows to generalise the topological phases of matter to systems with temperature.

The results found in this experiment with quantum simulators represent the first measurement of topological quantum phases with temperature, and advance the synthesis and control of topological matter using quantum technologies. Among other applications, the topological quantum matter could be used as hardware for future quantum computers due to its intrinsic robustness against errors. The experimental results presented in this work show how these topological quantum phases can also be robust against temperature effects.
-end-
Reference

Observation of topological Uhlmann phases with superconducting qubits, O. Viyuela, A. Rivas, S. Gasparinetti, A. Wallraff, S. Filipp, M.A. Martin-Delgado, NPJ Quantum Information, Volume 4, Article number: 10 (2018). DOI:10.1038/s41534-017-0056-9

QUITEMAD+

Related Topological Insulators Articles from Brightsurf:

Tunable THz radiation from 3D topological insulator
Wu's research group has been investigating a three-dimensional topological insulator of bismuth telluride (Bi2Te3) as a promising basis for an effective THz system.

Knotting semimetals in topological electrical circuits
Scientists created exotic states of matter using electrical circuit enhanced by machine-learning algorithm

Penn engineers create helical topological exciton-polaritons
Researchers at the University of Pennsylvania's School of Engineering and Applied Science are the first to create an even more exotic form of the exciton-polariton, one which has a defined quantum spin that is locked to its direction of motion.

Bridging the gap between the magnetic and electronic properties of topological insulators
Scientists at Tokyo Institute of Technology shed light on the relationship between the magnetic properties of topological insulators and their electronic band structure.

Topological superconducting phase protected by 1D local magnetic symmetries
Scientists from China and USA classified 1D gapped topological superconducting quantum wires with local magnetic symmetries (LMSs), in which the time-reversal symmetry is broken but its combinations with certain crystalline symmetries, such as MxT, C2zT, C4zT, and C6zT, are preserved.

Octupole corner state in a three-dimensional topological circuit
Higher-order topological insulators featuring quantized bulk polarizations and zero-dimensional corner states are attracting increasing interest due to their strong mode confinement.

Quantum simulation for 3D chiral topological phase
Professor Liu at PKU, Professor Du and Professor Wang at USTC build up a quantum simulator using nitrogen-vacancy center to investigate a three-dimensional (3D) chiral topological insulator which was not realized in solid state system, and demonstrate a complete study of both the bulk and surface topological physics by quantum quenches.

Photonic amorphous topological insulator
The current understanding of topological insulators and their classical wave analogues, such as photonic topological insulators, is mainly based on topological band theory.

Recent advances in 2D, 3D and higher-order topological photonics
A research team from South Korea and the USA has provided a comprehensive review covering the recent progress in topological photonics, a recently emerging branch of photonics.

Synthetic dimensions enable a new way to construct higher-order topological insulators
Higher-order topological insulators (HOTIs) are a new phase of matter predicted in 2017, involving complicated high-dimensional structures which show signature physical effects called ''corner modes.'' Now, scientists have proposed a recipe to construct such HOTIs and observe corner modes for photons in simpler, lower-dimensional structures by harnessing an emerging concept called ''synthetic dimensions.'' This construction allows flexible tuning of the topological behavior and opens avenues for even more exotic phases of photons in very high dimensions.

Read More: Topological Insulators News and Topological Insulators Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.