Time-evolution simulation of a controlled-NOT gate with two coupled asymmetric quantum dots

Abstract

We study a possible physical realization of a quantum controlled-NOT gate with the use of two weakly coupled asymmetric quantum dots. Solving the time-dependent Schrödinger equation for the model twoelectron system, we simulate the infrared-radiation-induced quantum transitions that correspond to basic gate operations. We require the transition probabilities to be close to 1 and optimize the parameters of the nanostructure in order to make the gate operation time as short as possible. In the simulations, we have taken into account the entire energy spectrum, which can be populated by the absorption or emission of the infrared radiation. We discuss the consequences of the existence of many bound two-electron states on the probability of radiative transitions.

Control of a double quantum dot structure by stimulated Raman adiabatic passage

“…2(b) θ = π/4, so the superposition (|0 − |1 )/ √ 2 is created. We note that the pulses used in STIRAP need not be of a specific shape or area, in contrast to the other approaches that have been proposed in such systems [1][2][3][4]. The choice of Gaussian pulses in the above examples was made only for convenience.…”

“…Several interesting phenomena have been recognized when the quantum dot structure contains one or two electrons. Examples include controlled transfer of electrons between the two quantum dots [1,3] and creation of maximally entangled states in two-electron quantum dot systems [2,4]. These effects are of central interest in the topical area of quantum computation as quantum dots are artificially created structures with potential scalability, so they are one of the most important candidates for realizing solid state quantum computation.…”

“…Examples include controlled transfer of electrons between the two quantum dots [1,3] and creation of maximally entangled states in two-electron quantum dot systems [2,4]. These effects are of central interest in the topical area of quantum computation as quantum dots are artificially created structures with potential scalability, so they are one of the most important candidates for realizing solid state quantum computation.In this work we study the potential for coherent manipulation of an asymmetric double quantum dot structure [3,4] by the use of adiabatic methods. These methods are the Stimulated Raman Adiabatic Passage (STIRAP) [5] and its modification the fractional STIRAP [6].…”

“…We show that such a method can be used for complete electron transfer between the two lower states of the quantum dots. In addition, with fractional STIRAP a coherent superposition of the two lower states of the quantum dots can be created.1 Introduction The interaction of electrons confined in double quantum dot structures with electromagnetic driving fields has attracted much attention in the past decade [1][2][3][4]. Several interesting phenomena have been recognized when the quantum dot structure contains one or two electrons.…”

Entanglement of two interacting electrons in a driven double quantum dot structure

“…In particular the creation of entangled states of two electrons in these structures has been studied in detail [1][2][3][4][5][6][7][8][9].In this work we revisit the quantum dot system studied by Zhang et al [5]. We study the case where the quantum dot system interacts with an electromagnetic pulse and present a method that is based on controlled rotation [10] for the creation of two-electron Bell entangled states.…”