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Pumped double quantum dot with spin-orbit coupling.

Khomitsky D, Sherman E - Nanoscale Res Lett (2011)

Bottom Line: Two types of external perturbation are considered: a periodic field at the Zeeman frequency and a single half-period pulse.Spin-orbit coupling leads to a nontrivial evolution in the spin and orbital channels and to a strongly spin- dependent probability density distribution.Both the interdot tunneling and the driven motion contribute into the spin evolution.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physical Chemistry, Universidad del País Vasco, 48080 Bilbao, Spain. evgeny_sherman@ehu.es.

ABSTRACT
We study driven by an external electric field quantum orbital and spin dynamics of electron in a one-dimensional double quantum dot with spin-orbit coupling. Two types of external perturbation are considered: a periodic field at the Zeeman frequency and a single half-period pulse. Spin-orbit coupling leads to a nontrivial evolution in the spin and orbital channels and to a strongly spin- dependent probability density distribution. Both the interdot tunneling and the driven motion contribute into the spin evolution. These results can be important for the design of the spin manipulation schemes in semiconductor nanostructures.PACS numbers: 73.63.Kv,72.25.Dc,72.25.Pn.

No MeSH data available.


Motion driven by the single-pulse field. Upper panel: Bz = 1.73T, Δz = ΔEg/2, and Tz(Bz) = 90 ps; lower panel: Bz = 6.92T, Δz = 2ΔEg, and Tz(Bz) = 22 ps Black line is the probability to find the electron in the right quantum dot. Red and blue dashed lines show corresponding spin components, as marked near the lines, determined both by the spin-orbit coupling and external magnetic field.
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Figure 3: Motion driven by the single-pulse field. Upper panel: Bz = 1.73T, Δz = ΔEg/2, and Tz(Bz) = 90 ps; lower panel: Bz = 6.92T, Δz = 2ΔEg, and Tz(Bz) = 22 ps Black line is the probability to find the electron in the right quantum dot. Red and blue dashed lines show corresponding spin components, as marked near the lines, determined both by the spin-orbit coupling and external magnetic field.

Mentions: As the second example we consider the probabilities ωR(t) and for the pulse-driven motion, presented in Figure 3. As one can see in the figure, the initial stage is the preparation for the tunneling, which develops only after the pulse is finished. Electric field of the pulse induces the higher-frequency motion by involving higher-energy states, as can be seen in the oscillations at t ≤ Tz (Bz)/2, however, prohibits the tunneling. Such a behavior of the probability and spin density can be explained by taking into account the detailed structure of matrix elements xnm. Namely, due to the symmetry of the eigenfunctions in a symmetric double QW the largest amplitude can be found for the matrix element of -operator for the pairs of states with opposite space parity having the same dominating spin projection. Hence, the dynamics involving all four lowest levels first of all triggers the transitions inside these pairs which do not involve the spin flip and only after this the spin-flip processes can become significant. As a result, Figure 3 shows that the spin flip has only partial character while the free tunneling dominates as soon as the pulse is switched off. A detailed description of other processes of nonresonant driven dynamics in the case of a half-period perturbation can be found in ref. [21].


Pumped double quantum dot with spin-orbit coupling.

Khomitsky D, Sherman E - Nanoscale Res Lett (2011)

Motion driven by the single-pulse field. Upper panel: Bz = 1.73T, Δz = ΔEg/2, and Tz(Bz) = 90 ps; lower panel: Bz = 6.92T, Δz = 2ΔEg, and Tz(Bz) = 22 ps Black line is the probability to find the electron in the right quantum dot. Red and blue dashed lines show corresponding spin components, as marked near the lines, determined both by the spin-orbit coupling and external magnetic field.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211269&req=5

Figure 3: Motion driven by the single-pulse field. Upper panel: Bz = 1.73T, Δz = ΔEg/2, and Tz(Bz) = 90 ps; lower panel: Bz = 6.92T, Δz = 2ΔEg, and Tz(Bz) = 22 ps Black line is the probability to find the electron in the right quantum dot. Red and blue dashed lines show corresponding spin components, as marked near the lines, determined both by the spin-orbit coupling and external magnetic field.
Mentions: As the second example we consider the probabilities ωR(t) and for the pulse-driven motion, presented in Figure 3. As one can see in the figure, the initial stage is the preparation for the tunneling, which develops only after the pulse is finished. Electric field of the pulse induces the higher-frequency motion by involving higher-energy states, as can be seen in the oscillations at t ≤ Tz (Bz)/2, however, prohibits the tunneling. Such a behavior of the probability and spin density can be explained by taking into account the detailed structure of matrix elements xnm. Namely, due to the symmetry of the eigenfunctions in a symmetric double QW the largest amplitude can be found for the matrix element of -operator for the pairs of states with opposite space parity having the same dominating spin projection. Hence, the dynamics involving all four lowest levels first of all triggers the transitions inside these pairs which do not involve the spin flip and only after this the spin-flip processes can become significant. As a result, Figure 3 shows that the spin flip has only partial character while the free tunneling dominates as soon as the pulse is switched off. A detailed description of other processes of nonresonant driven dynamics in the case of a half-period perturbation can be found in ref. [21].

Bottom Line: Two types of external perturbation are considered: a periodic field at the Zeeman frequency and a single half-period pulse.Spin-orbit coupling leads to a nontrivial evolution in the spin and orbital channels and to a strongly spin- dependent probability density distribution.Both the interdot tunneling and the driven motion contribute into the spin evolution.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physical Chemistry, Universidad del País Vasco, 48080 Bilbao, Spain. evgeny_sherman@ehu.es.

ABSTRACT
We study driven by an external electric field quantum orbital and spin dynamics of electron in a one-dimensional double quantum dot with spin-orbit coupling. Two types of external perturbation are considered: a periodic field at the Zeeman frequency and a single half-period pulse. Spin-orbit coupling leads to a nontrivial evolution in the spin and orbital channels and to a strongly spin- dependent probability density distribution. Both the interdot tunneling and the driven motion contribute into the spin evolution. These results can be important for the design of the spin manipulation schemes in semiconductor nanostructures.PACS numbers: 73.63.Kv,72.25.Dc,72.25.Pn.

No MeSH data available.