Ultra-high precision optical-phase tracking Toward optical communications and measurements beyond the limits of conventional physics

September 27, 2012

Optical-phase tracking © Shuntaro Takeda
Input light is measured, and the measurement results are fed back to the detector so that the detector is optimized.

The research group of Professor Akira Furusawa and Project Lecturer Hidehiro Yonezawa (Graduate School of Engineering, the University of Tokyo) have demonstrated ultra-high precision measurements of time-varying optical phase. The researchers exploited phase squeezed lights (the phase noise of which is smaller than that of a laser beam) and feedback control techniques to realize “optical-phase tracking” and exceed the classical mechanical boundary of precision. Moreover, this research revealed that there is a quantum mechanical limitation due to Heisenberg’s uncertainty principle in highly precise optical-phase tracking. Such ultra-high precision phase measurements will provide a stimulus to applied research in many fields such as ultra-precise length measurement, ultra-high capacity coherent optical communication, and absolutely secure quantum cryptography.

This research was conducted in collaboration with Griffith University, The University of New South Wales, University of Queensland, and Macquarie University in Australia.

This work was partly supported by the Project for Developing Innovation Systems.

Press release


Hidehiro Yonezawa, Daisuke Nakane, Trevor A. Wheatley, Kohjiro Iwasawa, Shuntaro Takeda, Hajime Arao, Kentaro Ohki, Koji Tsumura, Dominic W. Berry, Timothy C. Ralph, Howard Wiseman, Elanor Huntington, Akira Furusawa,
“Quantum-Enhanced Optical-Phase Tracking”,
Science 337 (2012): 1514-1517, doi: 10.1126/science.1225258.
Article link


Graduate School of Engineering

Department of Applied Physics

Furusawa laboratory

Access Map
Kashiwa Campus
Hongo Campus
Komaba Campus