Optical Electron Transfer between Quantum Dots

Башаров, А. М.; Dubovis, S. A.

doi:10.1134/1.2135854

Cited by 15 publications

(13 citation statements)

References 13 publications

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“…IV C to account for our numerical results reflecting very small influence of high-lying states of discrete part of HMI spectrum on electron dynamics. In principle, the continuum states being addressed directly can also be used as transport channels, but, at the same time, can bring about additional decoherence (see, e.g., [32]). …”

Section: Discussionmentioning

confidence: 99%

Single-qubit operations in the double-donor structure driven by optical and voltage pulses

Tsukanov

2007

Phys. Rev. B

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We study theoretically the quantum dynamics of an electron in the singlyionized double-donor structure in the semiconductor host under the influence of laser pulses whose frequencies are close to structure resonant frequencies. This system can be used as a charge qubit where the logical states are defined by the lowest two energy states of the remaining valence electron localized around one or another donor. The quantum operations are performed via resonant or Raman-like transitions between the localized (qubit) states and the excited states delocalized over the structure, combined with phase shifts between qubit states generated by voltage pulses. The possibility of realization of arbitrary single-qubit rotations is demonstrated.

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Section: Discussionmentioning

confidence: 99%

Single-qubit operations in the double-donor structure driven by optical and voltage pulses

Tsukanov

2007

Phys. Rev. B

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“…can be used as logical states of a quantum bit (qubit), the logical |0 (|1 ) being associated with the state |L (|R ) localized in the left (right) double-well potential minimum. These so-called charge qubits can be manipulated, e.g., by applying adiabatically switched gate voltages [6,7,8,9,26] or laser pulses (both resonant and off-resonant) [13,36,37,38,39] to the system.…”

Section: Discussionmentioning

confidence: 99%

“…Substituting expressions (39), (40), (41), (42) into Eq. (44), and neglecting, as above, the terms of the order of |g β | 4 , we obtain the density matrix elements in the energy basis:…”

Section: (I) Strongly Asymmetric Double-well Potential (Ementioning

confidence: 99%

Phonon-induced decoherence of the two-level quantum subsystem due to relaxation and dephasing processes

Openov

2008

Physics Letters A

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Phonon-related decoherence effects in a quantum double-well two-level subsystem coupled to a solid are studied theoretically by the example of deformation phonons. Expressions for the reduced density matrix at T = 0 are derived beyond the Markovian approximation by means of explicit solution of the non-stationary Schrödinger equation for the interacting electron-phonon system at the initial stage of its evolution. It is shown that as long as the difference between the energies of the electron in the left and the right well greatly exceeds the energy of the electron tunneling between the minima of the double-well potential, decoherence is primarily due to dephasing processes. This case corresponds to a strongly asymmetric potential and spatially separated eigenfunctions localized in the vicinity of one or another potential minimum.In the opposite case of the symmetric potential, the decoherence stems from the relaxation processes, which may be either "resonant" (at relatively long times) or "nonresonant" (at short times), giving rise to qualitatively different temporal evolution of the electron state. The results obtained are discussed in the context of quantum information processing based on the quantum bits encoded in electron charge degrees of freedom.

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“…As will be shown below, the problem of laserinduced transitions |0 → |1 , |1 → |0 in such a four-level system allows for an exact solution within the standard rotating wave approximation (RWA), without additional approximations like the adiabatic elimination of high-lying levels [32]. Relatively simple analytical expressions for the dependencies of the state amplitudes on time not only help to analyze the results of numerical calculations on much more complex systems [24,31] but enable to find out a novel regime of laser-iduced operations with charge qubits that differs from both resonant and nonresonant (in a commonly accepted interpretation [23,24,26]) regimes.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, much attention is now paid to the charge qubits based on the tunnel-coupled quantum dots [5][6][7]13,15] or a singly ionized pair of donor atoms nearby the surface [8,[16][17][18], the basis qubit states |0 and |1 being the orbital electron states |L and |R localized in different (left and right) quantum dots or at different donor sites. Operations with such qubits can be implemented, first, through the changes in the energies E L , E R of the states |L , |R and the height of the barrier separating the minima of the double-well potential (by the adiabatic changes in the voltages at corresponding gates [5][6][7][8]) and, second, through the influence of the resonant (tuned to the resonance with one of the excited levels that plays a role of the "transport" level) or nonresonant laser pulse [13,[18][19][20][21][22][23][24][25][26]. τ on the time t op of single-qubit operations [16][17][18][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Laser-induced operations with charge qubits in a double-well nanostructure

Voronko

Openov

2008

Physics Letters A

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We present the results of theoretical studies on operations with charge qubits in the system composed of two tunnel-coupled semiconductor quantum dots whose two lowest states (localized in different dots) define the logical qubit states while two excited states (delocalized between the dots) serve for the electron transfer from one dot to another under the influence of the laser pulse. It is shown that in the case of small energy separation between the excited levels, the optimal (from the viewpoint of minimal single-qubit operation time and maximum operation fidelity) strategy is to tune the laser frequency between the excited levels. The pulse parameters for implementation of the quantum NOT operation are determined. Analytical results obtained in the rotating-wave approximation are confirmed by rigorous numerical calculations.

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Optical Electron Transfer between Quantum Dots

Cited by 15 publications

References 13 publications

Single-qubit operations in the double-donor structure driven by optical and voltage pulses

Single-qubit operations in the double-donor structure driven by optical and voltage pulses

Phonon-induced decoherence of the two-level quantum subsystem due to relaxation and dephasing processes

Laser-induced operations with charge qubits in a double-well nanostructure

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