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September 30, 2022

The Honda Prize 2022 Dr. Hidetoshi Katori, Professor, the Graduate School ofEngineering, The University of Tokyo—Invention of an optical lattice clock that only loses one second in 30 billion years
The Honda Foundation, the public interest incorporated foundation established by Soichiro
Honda and his younger brother Benjiro and currently led by President Hiroto Ishida, ispleased to announce that the Honda Prize 2022 will be awarded to Dr. Hidetoshi Katori,Professor, the Graduate School of Engineering, The University of Tokyo (Chief Scientist andTeam Leader, RIKEN) for his invention an optical lattice clock that is 1,000 times more precise
than conventional atomic clocks.
The Honda Prize, established in 1980 and awarded annually, is an international award thatrecognizes the work of individuals or groups generating new knowledge that will drive thenext generation from the standpoint of ecotechnology.*1 Dr. Katori invented in 2001 a novel
optical atomic clock that uses a large number of atoms trapped in an optical lattice to provide
an ultra-high precision time and frequency standard. In contrast to the cesium atomic clocks*2that keep the International Atomic Time with an accuracy of about 15 digits*3, the opticalatomic clocks are expected to allow 18-digit precision by employing optical transitions thathave tens of thousand times higher frequency than microwave frequency. At this precision, it
takes 30 billion years to lose one second.
This precision enables relativistic geodesy capable of measuring a height difference of one
centimeter on Earth based on the relativistic effect that time flows slowly for a strong
gravitational field. For example, relativistic geodesy may be applied to disaster prevention,such as detecting the rise of volcanic magma by clocks set on the mountain. The high-precision
clocks will open up new measurement technologies and research fields.
The origin of ecotechnology is in Soichiro Honda's words, "Make people happy withtechnology." The improvement in accuracy of one second is expected to have an immeasurable
impact on mankind. The Prize will be awarded to Dr. Katori for this groundbreaking invention,
which is worthy of the highest recognition.

-1-<Research on the optical lattice clock by Dr. Katori>
The importance of precision time measurement is growing ever greater in modern society eachyear. It forms an infrastructure vital to all social activities, including the Global Navigation
Satellite System (GNSS) with atomic clocks on board, timestamps used in e-commerce, andprecision measurements employed in cutting-edge science and technology.
At present, the definition of "one second" in the International System of Units (SI) isbased on the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom.
International Atomic Time based on the cesium atomic clocks (with a microwave frequency ofapprox. 9.2 GHz) has an accuracy of about 15 digits. However, the optical atomic clock thatuses optical transitions with a higher than microwave frequency holds the potential to create
atomic clocks with higher precision. The most promising candidate for an optical atomic clock
has been considered to be a clock based on a singly trapped ion in which the transition
frequency of a single ion, cooled to ultracold temperature and trapped between electrodes, isrepeatedly measured over a million times to achieve 18-digit precision. As each measurementtakes one second, a million seconds (10 days) of averaging time is required.
Instead of averaging one million
seconds, Dr. Katori conceived of an opticallattice clock to dramatically reduce theaveraging time by measuring many atoms
at a time. Atoms are trapped in an opticallattice created by the standing wave oflight*4 to reduce the Doppler effect causedby the atomic motion. At the same time,thequantum

noiseisreducedbyaveraging the signal from many trappedatoms. He proposed and demonstrated that

Schematic representation of an optical lattice©2015 Hidetoshi Katori

the optical lattice does not affect theeigenfrequency of the atoms by tuning the laser to the magic wavelength*5 to create the lattice.
Such high-precision atomic clocks have been mainly studied in the laboratory, as they
are consisted of many components and are sensitive to environmental conditions. The researchteam led by Dr. Katori conducted an experiment to compare two downsized optical latticeclocks—one installed on the observation deck and the other on the ground floor of Tokyo
SkyTree, which is a broadcasting tower in Tokyo. In April 2020, the team published a paper
reporting that the clock on the deck ticked faster by 4/1,000,000,000 of a second per day thanthe clock on the ground. This triggered a huge response from around the world, as theexperiment verified Einstein's general theory of relativity with a precision comparable to thatof spaceborne experiments using rockets and satellites, despite a height difference of only 450
meters. This demonstration was the first step toward relativistic geodesy employing highprecision atomic clocks.
-2-Dr. Katori is presently working on the further downsizing of the optical lattice clock.
While the SkyTree clock has a volume of approximately 1,000 liters, a smaller machine with avolume of 1/5 is underdevelopment. When continuous and stable operation of such
downsized clocks becomes possible, a network of optical lattice clocks can be realized byinstalling them in various locations. The clock network will not only provide time referencewith a precision far higher than GNSS but also will be able to detect spacetime curved bygravity, thus allowing precision monitoring and investigation of the environment on theearth’s surface, as well as the oceans, climate, and crustal movements. For example, real-timemonitoring of crustal movements may be used to study precursors of earthquakes.
*1 Ecotechnology: a neologism combining imaging of the natural world (ecology), including
civilization as a whole, and technology. Advocated by the Honda Foundation in 1979, it seeks newtechnological concepts required by human society to further the coexistence of people andtechnology.
*2 Cesium atomic clock: an atomic clock that uses the cesium 133 atom. Atomic clocks rely on theproperty of atoms to emit and absorb electromagnetic waves with a certain frequency. The
duration for the electromagnetic waves to oscillate 9,192,631,770 times, which is generated bycesium transition, defines one second and is used to keep the International Atomic Time, since the13th General Conference of Weights and Measures in 1967. The accuracy of the cesium clock
corresponds to a loss of 1 second in 60 million years.
*3 International Atomic Time accuracy of about 15 digits: accurate enough to measure with afractional accuracy with one part in 1015.
*4 Standing waves: frequency waves with a fixed amplitude distribution in space.
*5 Magic wavelength: the wavelength where the polarizabilities of two electronic states used for theclock transition become equal. Because the polarizability of the atomic state depends on theelectronic state, the light shift likewise differs with the electronic state. This results in a change inthe resonant frequency of atoms trapped in the optical lattice. However, the optical lattice createdwith a laser tuned to the magic wavelength equalizes the polarizability for the two states and does
not affect the resonant frequency of trapped atoms.

For more information, contact the Honda Foundation via:
phone at +81-3-3274-5125 or fax at +81-3-3274-5103
Honda Yaesu Building, 2-6-20 Yaesu, Chuo-ku, Tokyo 104-0028, Japan
https://www.hondafoundation.jp/en/
You may also contact Honda Motor’s Corporate PR Department via phone at +81-3-54121512.

-3-Dr. Hidetoshi Katori- Professor, Department of Applied Physics,
Graduate School of Engineering, The University of Tokyo- Chief Scientist, Quantum Metrology Laboratory /Team Leader, Space-Time Engineering Research Team,RIKEN Center for Advanced Photonics (RAP), RIKEN- Program Manager, JST-MIRAI Program,
Japan Science and Technology Agency
Born
September 27, 1964, Japan

Education and Qualifications
1988

B. Eng. in Applied Physics, Faculty of Engineering, The University of Tokyo

1990

M. Eng. in Applied Physics, Graduate School of Engineering, The University of Tokyo

1994

D. Eng. in Applied Physics, Graduate School of Engineering, The University of Tokyo

Scientific Positions
1991

Research Associate, Department of Applied Physics, Faculty of Engineering,
The University of Tokyo

1994

Guest Scientist, Max Planck Institute for Quantum Optics, Garching, Germany

1997Group Leader, ERATO Gonokami Cooperative Excitation Project,
Japan Science and Technology Corporation

1999

Associate Professor, Engineering Research Institute, Faculty of Engineering,
The University of Tokyo

2005

Associate Professor, Department of Applied Physics, Graduate School of Engineering,
The University of Tokyo
Principal Investigator, CREST, Japan Science and Technology Agency

2010～presentProfessor, Department of Applied Physics, Graduate School of Engineering,
The University of Tokyo

2010～2016

Research Director, ERATO Katori Innovative Space-Time Project,
Japan Science and Technology Agency

2011～present

Chief Scientist, Quantum Metrology Laboratory, RIKEN

2014～present

Team Leader, Space-Time Engineering Research Team,RIKEN Center for Advanced Photonics (RAP), RIKEN

2014～2022Distinguished Guest Professor, University of Tübingen

2018～presentProgram Manager, Space-time information platform with a cloud of optical lattice clocks,JST-Mirai Program, Japan Science and Technology Agency

Awards
2001Marubun Research Award

2005 The European Frequency and Time Award
The 1st JSPS (Japan Society for the Promotion of Science) Prize
Julius Springer Prize for Applied Physics
2006 Marubun Special Science AwardThe 20th IBM Japan Science Prize2008 Rabi Award
2010 The 42nd Ichimura Academic Award, Special Prize2011 The 12th Optics and Quantum Electronics Achievement Prize (Hiroshi Takuma Award)
The Commendation for Science and Technology by the Minister of Education, Culture, Sports,
Science and Technology, Prizes for Science and Technology, Research Category
The Philipp Franz von Siebold Prize2012 Asahi Prize 20112013 The 53rd Toray Science and Technology Prize
The 54th Fujihara Award
Nishina Memorial Prize2014 Medal with Purple Ribbon
2015 Japan Academy Prize
2016 JSAP (The Japan Society of Applied Physics) Outstanding Achievement Award 20152017 Leo Esaki Prize
2020 The 90th Anniversary Special Award from the Hattori Foundation
The Micius Quantum Prize 20202022 Breakthrough Prize in Fundamental Physics

Academic Society
The Physical Society of Japan, The Japan Society of Applied Physics, The Laser Society of Japan, American
Physical Society, The Engineering Academy of Japan