Formulas for processes occurring in quantum dots are derived

Quantum dot is a fragment of a conductor or semiconductor whose charge carriers (electrons or holes)

limited in space on all threemeasurements. The size of a quantum dot must be small enough for quantum effects to be significant. This is achieved if the kinetic energy of the electron is noticeably greater than all other energy scales: first of all, greater than the temperature, expressed in energy units.

Rui sakano

Quantum dot (yellow) connected to twoelectrodes (blue). Electrons tunneling into the quantum dot from the electrodes interact with each other to form a highly correlated quantum state called a "Fermi liquid"

Japanese physicists have developed formulas forto describe the physical phenomenon occurring inside quantum dots and other nanoscale materials. This process is also called the “Kondo effect”: in 1964, theoretical physicist June Kondo described it for some magnetic materials. It is now known that it occurs in many other systems, including quantum dots.

Typically the electrical resistance of metalsdecreases with decreasing temperature. However, this does not work with metals that contain magnetic impurities; this only occurs up to a critical temperature. Above it, the resistance increases as the temperature decreases.

In order to derive the formula, the authorscompiled a mathematical description of the evolution of this cloud: they began with the state of the system at absolute zero, to which the well-established theoretical Fermi liquid model for interacting electrons is applicable. And as a second step, they introduced an amendment that describes the system’s response to external disturbances. 

As a result, the formulas reflect the work of electrons in such systems in two different ways

The predictions of the formulas can soon be tested experimentally. Research for this project has just begun. 

Akira Oguri research director at Osaka City University from the Institute of Theoretical and Experimental Physics

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