PORTLAND, Ore. — The first demonstration of high-temperature superconductivity in the surface of a topological insulator -- a promising material for quantum computers -- was reported this week by Lawrence Berkeley National Laboratory (Berkeley Lab).
Topological insulators are a unique class of new materials whose bulk properties are that of an insulator, but whose top layer is conducting. Their advantage for future quantum computers is that they are predicted to support what are called Majorana zero modes, which would make the q-bits stored there nonvolatile.
Eryin Wang (left) and Alexei Fedorov at ALS Beamline 12.0.1 where the induced high-temperature superconductivity in a topological insulator was confirmed.
(Source: Roy Kaltschmidt, LBL News Center)
Quantum computers hold the promise of easily solving the kind of combinatorial problems that are difficult for conventional computers -- such as sifting through vast databases -- which today requires that computers check and compare each record separately. However, quantum computers could sift through all records simultaneously, picking out the optimal solution is a single step.
Unfortunately, the q-bits used in quantum computers are very fragile, and subject to a phenomenon called decoherence, which destroys their reliability at quickly finding optimal solutions; fixing the unreliability requires sophisticated error-correction techniques.
Bismuth selenide cuprate (Bi2212) heterostructure showed proximity-induced high-temperature superconducting gap on the surface states of the bismuth selenide topological insulator.
Now, Berkeley Lab used its Advanced Light Source (ALS) has confirmed that a bismuth selenide topological thin film heterostructure, made at China's Tsinghua University (Beijing) in the laboratory of Xi Chen and Qi-Kun Xue using molecular beam epitaxy, is a high-temperature superconductor that may house Majorana zero modes opening the door to its potential use for future quantum computers.
"Up until now, these Majorana zero modes have just been theoretical," said Alexei Fedorov, a staff scientist for ALS at Berkeley Lab in an interview with EE Times. "We have characterized this new material and found that it is a good candidate to look for Majoran zero modes. The next step will be to set up an experiment to look for this effect."
Majoran zero modes, which are naturally immune from decoherence, would enable fault-tolerant quantum computers to be more easily built, since the q-bits stored there would be non-volatile.
Other researchers on the project include Eryin Wang of Tsinghua University, who is currently an ALS doctoral fellow in residence at Berkeley Lab, as well as other Tsinghua University researchers, including Shuyun Zhou Hao Ding and Xi Chen. Funding was provided by the National Natural Science Foundation of China.