RIKEN, NEC Corporation, and JST (“Japan Science and Technology Agency”) have successfully demonstrated a laser emission from one artificial atom by coupling superconducting quantum bits (“qubits”) to a resonator. The lasing effect was achieved by an extremely simple system – a single “atom” coupled to a resonator – and represents a world first in the use of a superconducting qubit as an artificial atom to generate lasing photons.
The laser emission system leverages several features of the superconducting qubit – the basic circuits of a quantum computer. For example, the qubit can be easily used as a mediator in the resonator, and also allows easy control of the circuit parameters by varying the gate potential and the local magnetic field.
Application of a nano-ampere current to the superconducting qubit enabled the resonator to emit a photon every 0.5 nanoseconds, and a laser with a frequency of approximately 10 GHz (in the microwave range) was detected. Shooting a microwave at the system from an external source increased the power almost three fold, aligning the waves to demonstrate the emission to be a laser.
The emission system is expected to contribute to both fundamental and applied research on lasers. In particular, it may facilitate the development of an information system for converting electronic information to microwaves, the compact microwave source that is necessary to control and read qubits, and the quantum code that will be essential for absolutely secure information management.
This research was carried out as part of “Developing a superconducting qubit system”, under JST’s CREST project “Creation of New Technology Aiming for the Realization of Quantum Information Processing Systems”, and was led by Dr. J. S. Tsai, Team Leader of RIKEN’s Macroscopic Quantum Coherence Laboratory and Chief Researcher at NEC’s Nano Electronics Research Laboratories. Further details of this research were published on October 4 by Nature journal of science.
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The Riken Institute was first founded in 1917 as a private research foundation known as ‘RIKEN’. In 2003, it was reorganized as an Independent Administrative Institution under the Ministry of Education, Culture, Sports, Science and Technology, since when it has engaged in wide-ranging research activities that span basic to applied science. The objectives of RIKEN are to conduct comprehensive research in science and technology (excluding only humanities and social sciences) under the ‘Riken Law’, and to disseminate the results of its scientific research and technological developments. Riken carries out high-level experimental and research work in a wide range of fields, including physics, chemistry, medical science, biology and engineering extending from basic research to practical application.
The Japan Science and Technology Agency (JST) mission is to promote science and technology in Japan by conducting a broad range of activities, including promotion of consistent research and development from basic research to commercialization with particular emphasis on the creation of new technological seeds, and upgrading the infrastructure for the promotion of science and technology, including dissemination of scientific and technological information. Under the independent administrative institution system, the realization of voluntary and self-reliant operation of activities, and the pursuit of operations more effective than those of the past is required.