Scientists discover new optically active quantum dot mechanism
Market Information Network 2023-01-30 11:37:45 Source: People’s Daily Online Comments:
Original title: Discovery of a new optically active quantum dot mechanism
Optically active semiconductor quantum dots are the most efficient spin-photonic interfaces known so far, and despite 10 years of research, scientists have struggled to extend their storage beyond a few microseconds. In a new study, researchers at the Universities of Cambridge, Linz and Sheffield have demonstrated that there is a simple material that can solve this problem, increasing the storage of quantum information to more than a hundred microseconds. The research results were published in the recent “Nature Nanotechnology”.
Quantum dots are crystalline structures made up of thousands of atoms. Each nucleus of these atoms has a magnetic dipole moment that couples to the quantum dot electrons and can cause the loss of quantum information stored in the electronic qubits. New research finds that in devices built from semiconductor materials with the same lattice parameters, atomic nuclei “feel” the same environment and behave consistently. The result is that this kernel noise can be filtered out and an improvement of nearly two orders of magnitude in storage time can be achieved.
According to the researchers, this is a novel mechanism for optically active quantum dots, in which the interaction with the nucleus is turned off and the electron spin is refocused over and over again to keep its quantum state active. For spins in quantum dots, the short coherence time is the biggest obstacle to application, and this finding provides a clear and simple solution for this.
In exploring the hundred-microsecond timescale for the first time, the researchers were pleasantly surprised to find that the electrons only see noise from the nucleus, not the electrical noise in the device.
Another thing that surprised the researchers was the “sound” received from the nucleus. It’s not as harmonious as initially expected, and there’s room for further improvement in the system’s quantum coherence through further material improvements.
One of the most exciting things about this research, the researchers say, is taming a complex quantum system: a hundred thousand atomic nuclei strongly coupled to a single well-controlled electron spin. Most researchers tackle the problem of isolating qubits from noise by eliminating all interactions. Their qubit became a bit like a sedated Schrödinger’s cat, unable to respond to anyone pulling its tail. The “cats” in the new study appear to be on powerful stimulants.
Quantum dots now combine high photon quantum efficiency with long spin coherence times. In the near future, the researchers envision these devices being able to create entangled light states for all-photonic quantum computing and allow fundamental quantum control experiments on nuclear spin systems. (Reporter Zhang Mengran)
Original manuscript link: http://edu.people.com.cn/n1/2023/0129/c1006-32613570.html
Editor in charge: Liu Yuan