More than one word changes from quantum dot to quantum ring
Quantum computing has become one of the hottest research projects nowadays, and the implementation of quantum bits as an information carrier is a key technology in quantum computer research.
Recently, researchers from the Institute of Microelectronics, Chinese Academy of Sciences, and Inspur Electronic Information Industry Co., Ltd. jointly published research papers jointly by Chongqing University of Posts and Telecommunications and Xiamen University, put forward the theoretical assumption of constructing quantum computers with multi-electron semiconductor quantum rings, Quantum bit implementation.
As the author of the article, Wu Zhenhua, a researcher at the IC R & D Center of the Institute of Microelectronics of the Chinese Academy of Sciences, said in an interview with Science and Technology Daily: 'The construction of quantum bits with a semiconductor quantum ring is a new idea based on the existing mature semiconductor technology to build a quantum computer '
The transistor size is close to the physical limit
In the recent 40 years, the microelectronics industry has followed the prediction of Moore's Law and has continued its rapid development.
But with the progress of technology, device integration is higher and higher, the number of transistors on the chip is more and more, a single transistor size smaller and smaller.Can be said that the current semiconductor chip development has been close to the size of the physical limit, Moore's Law era is coming to an end, the urgent need to develop new computing principles and new device architecture to meet the growing computing needs. 'Wu Zhenhua explained that' in this context, scientists from all over the world vigorously study the laws of quantum mechanics, the development of quantum computing and quantum Information technology, with a view to developing a practical quantum computer that can replace the traditional computer to realize supercomputing ability of ultrahigh quantum parallelism.
Quantum computers increase computational power by stacking and entangling quantum phenomena, which allow quantum bits to have values of 0 and 1 simultaneously for 'synchronous computation.' With each additional quantum bit, computational performance doubles . "Another author of the paper, Dr. Liu Yu, Inspur AI and HPC said.
At present, Google, Microsoft, IBM, Intel and other technology companies have laid out quantum computing research.Liu Yu said that IBM claims to have successfully developed a 50 qubits bit prototype; Quantum hardware leader Google Google John Martins Then in October last year revealed that Google already has 22 qubits of chips; China also released in early May 2017 the world's first quantum computer beyond the early classical computer, the successful realization of the 10 superconducting quantum bit entanglement is expected in the near future The future can be manipulated 20 superconducting qubits.
Meet a few specific 'indicators' to be more good
Quality quantum bit implementations generally need to meet several specific requirements, such as easier physical implementation of the vector, easier initial preparation and manipulation, longer coherence times, and more.
At present, the implementations of quantum bits mainly include superconducting loops, trapped ions, semiconductor quantum dots, diamond vacancies, topological arbitrary molecules, photons, etc. Each of these technologies has its own advantages and disadvantages. The final route in the future is not yet clear Wu Zhenhua told reporters.According to him, the above program, the semiconductor quantum dot program has the most core advantages, which can make use of existing semiconductor technology based on the development, operation speed, easy to achieve high-density integration, which attracted many research institutions attention.
However, due to the strong quantum confinement effect in semiconductor quantum dots, the electron coherence time is short and the electronic entanglement is difficult. To solve this problem, we use the configuration interaction method to theoretically study the semiconductors including 3 to 6 electrons Quantum ring in the multi-electron state and found that the number of electrons in the quantum ring is different from the electron will be coupled to form different entangled state, and can be different with the applied magnetic field, electric field showing different characteristics in order to achieve quantum state regulation.In addition, Our research also systematically expounded the scheme of measuring the characteristics of quantum rings by optics, Liu Yu said.
Available with existing semiconductor technology
In the view of Wu Zhenhua and Liu Yu, constructing a quantum bit with a multi-electron semiconductor quantum ring is a new concept for the existing single-electron semiconductor quantum dot scheme.The main obstacle to quantum computing is that it is difficult to maintain the quantum state for calculation, Which means the coherence time is short.The research shows that compared with the semiconductor quantum dots, the confinement potential of the semiconductor quantum ring is easy to be adjusted and the electron coherence time is longer, which is conducive to more quantum bit manipulation.Quantum quantum dots can only conduct single electron spin Fine control of the experimental requirements difficult.Multiple electronic quantum ring using electronic hybrid quantum number and electron spin state quantum bits, so have more freedom to manipulate.In addition quantum dots, the electron is bound at zero Dimensional space.Electrons in quantum rings also have the freedom to orbital motion in quasi-one-dimensional space, providing new coding possibilities beyond the spin of such charges.
Not only that, like the semiconductor quantum dots, the quantum ring can also be realized by using the existing semiconductor process, so that the transition from the classical semiconductor chip to the quantum chip can be smoothed based on the prior art, "Wu Zhenhua said.
This new research result is still a fruitful result of the cooperation between industry, universities and research institutes. "Liu Yu said:" This study uses a more rigorous and accurate theoretical simulation method, but with a huge amount of computation. The Institute of Microelectronics and Inspur Group, Give full play to the advantages of Inspur in the field of HPC and both parties will continue to promote cooperation and seek new breakthroughs in the field of quantum computing.