Control as a “science to design movement”

Associate Professor Koji Tsumura
(Department of Information Physics and Computing)

Associate Professor Tsumura views control as “manipulation of movement as intended – a science to design movement” and researches widely applicable universal rules (control theory) and the development of control theory in specific application areas.  Control mechanisms are used with different targets as in controlling movements of automobiles and robots, keeping room temperature at 28°C by air conditioning, or maintaining body temperature at 36°C by human mechanisms.

One of the leading-edge researches Associate Professor Tsumura is engaged in is quantum control.  At the hearts of quantum information technology such as quantum computers are quantum bits (qubits), over which, using the spin of atoms and electrons, 1 or 0 is written depending on the spin direction – upward or downward.  Ultra high speed computation is achievable with quantum bits since 1 and 0 can be written (computed) in a superposition unlike normal computer devices.

In order to align the spin in the intended direction, the concept of feedback control may be used.  Associate Professor Tsumura established a method to confirm whether the spin is upward or downward and is in pursuit of the essence of quantum systems by making a breakthrough in feedback control of quantum system.

In addition to this quantum bit research in which control theory is applied to quantum information systems, his other research focus is networked control to discover a new universal control theory by unifying control theory and information theory.

When it comes to applying control theory to new areas such as quantum computers, communication, and measurement of biological phenomena, a new complementary tool is necessary as traditional control theory by itself is insufficient.  In other words, “system control theory” that incorporates new perspectives including information theory needs to be developed to address problems to which traditional control theory did not have solutions.  “Unification of control theory and information theory” is the vision of Associate Professor Tsumura to solve this challenge.