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Longitudinal wave function control in single quantum dots with an applied magnetic field.

Cao S, Tang J, Gao Y, Sun Y, Qiu K, Zhao Y, He M, Shi JA, Gu L, Williams DA, Sheng W, Jin K, Xu X - Sci Rep (2015)

Bottom Line: With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane.Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process.Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.

ABSTRACT
Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots.

No MeSH data available.


(a) The contour plots of the PL spectra of X2− and X− as a function of bias voltage from −0.5 V to +0.5 V at different magnetic fields. Due to the Zeeman splitting, four peaks of X2− and X− at high magnetic fields can be observed, as marked in the Figure. The solid black lines are used to guide the eyes for the Stark shifts. (b) Transition energies (black square) of X2− as a function of Etotal across the quantum dot. The solid red line shows the fitted result and the fitted parameters are shown in the inset. (c) Transition energies (black square) of the two branches of X2− at 7 T as a function of Etotal. The solid red lines are the fitted results of the Stark effect.
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f2: (a) The contour plots of the PL spectra of X2− and X− as a function of bias voltage from −0.5 V to +0.5 V at different magnetic fields. Due to the Zeeman splitting, four peaks of X2− and X− at high magnetic fields can be observed, as marked in the Figure. The solid black lines are used to guide the eyes for the Stark shifts. (b) Transition energies (black square) of X2− as a function of Etotal across the quantum dot. The solid red line shows the fitted result and the fitted parameters are shown in the inset. (c) Transition energies (black square) of the two branches of X2− at 7 T as a function of Etotal. The solid red lines are the fitted results of the Stark effect.

Mentions: Figure 2(a) shows the PL spectra of X− and X2− as a function of bias voltage at different magnetic fields applied along the growth direction, from base to apex of quantum dots. This direction is denoted as z direction in this work. It can be seen that both X− and X2− peaks split in the presence of the magnetic field due to Zeeman effect, and the average energy of the splitted peaks shifts to high energy under the diamagnetic effect. The relative intensity of X− increases with increasing magnetic field because the probability for the in-plane (xy plane) electrons being captured by quantum dot is reduced by the applied magnetic field in z direction as discussed before35.


Longitudinal wave function control in single quantum dots with an applied magnetic field.

Cao S, Tang J, Gao Y, Sun Y, Qiu K, Zhao Y, He M, Shi JA, Gu L, Williams DA, Sheng W, Jin K, Xu X - Sci Rep (2015)

(a) The contour plots of the PL spectra of X2− and X− as a function of bias voltage from −0.5 V to +0.5 V at different magnetic fields. Due to the Zeeman splitting, four peaks of X2− and X− at high magnetic fields can be observed, as marked in the Figure. The solid black lines are used to guide the eyes for the Stark shifts. (b) Transition energies (black square) of X2− as a function of Etotal across the quantum dot. The solid red line shows the fitted result and the fitted parameters are shown in the inset. (c) Transition energies (black square) of the two branches of X2− at 7 T as a function of Etotal. The solid red lines are the fitted results of the Stark effect.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306960&req=5

f2: (a) The contour plots of the PL spectra of X2− and X− as a function of bias voltage from −0.5 V to +0.5 V at different magnetic fields. Due to the Zeeman splitting, four peaks of X2− and X− at high magnetic fields can be observed, as marked in the Figure. The solid black lines are used to guide the eyes for the Stark shifts. (b) Transition energies (black square) of X2− as a function of Etotal across the quantum dot. The solid red line shows the fitted result and the fitted parameters are shown in the inset. (c) Transition energies (black square) of the two branches of X2− at 7 T as a function of Etotal. The solid red lines are the fitted results of the Stark effect.
Mentions: Figure 2(a) shows the PL spectra of X− and X2− as a function of bias voltage at different magnetic fields applied along the growth direction, from base to apex of quantum dots. This direction is denoted as z direction in this work. It can be seen that both X− and X2− peaks split in the presence of the magnetic field due to Zeeman effect, and the average energy of the splitted peaks shifts to high energy under the diamagnetic effect. The relative intensity of X− increases with increasing magnetic field because the probability for the in-plane (xy plane) electrons being captured by quantum dot is reduced by the applied magnetic field in z direction as discussed before35.

Bottom Line: With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane.Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process.Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.

ABSTRACT
Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots.

No MeSH data available.