It is our great honour to be able to organise the 21st RIES-Hokudai International Symposium and to welcome all the participants.

Due to the rapid world-wide spreading of the new coronavirus infections (COVID-19), we have decided to hold the symposium as an online virtual symposium on December 10-11, 2020.

Research Institute for Electronic Science (RIES) started as “Research Institute of Ultrashort Waves” in 1943 is now conducting a diverse range of science including optical science, material science, life science and mathematics under the mission of development of new interdisciplinary fields. For this purpose, we carry out several programs to encourage active interactions between researchers in different research fields. The International Symposium having been held annually since 1999 is one of the most important events.

The symposium each year has been symbolised by a single "Kanji" (aChinese character). The “Kanji” in 2020 is the character “間” [ma] whichgenerally denotes “distance”, "interval", “scale”, and means also “between” or “across the space separating”. Although we need to keep physical distance each other under this circumstance, we wish to bridge across the space and develop the interdisciplinary research field through scientific collaborations. I wish that this symposium could be an opportunity for it.

I expect the present symposium would be fruitful and positive for all the participants to be much stimulated and to obtain inspirations on science.

Representing the organising committee of 21st RIES-Hokudai International Symposium,
Prof. Hiroshi Uji-i,
the chair of 21st RIES-Hokudai International Symposium