Voltage-controlled coded qubit based on electron spin

Abstract

We design and analyze a solid state qubit based on electron spin and controlled by electrical means. The coded qubit is composed of a three-electron complex in three tunable gated quantum dots. The two logical states of a qubit, |0L and |1L , reside in a degenerate subspace of total spin S = 1/2 states. We demonstrate how applying voltages to specific gates changes the one-electron properties of the structure, and show how electron-electron interaction translates these changes into the manipulation of the two lowest energy states of the three-electron complex.

Electron-electron interactions, topological phase, and optical properties of a charged artificial benzene ring

“…Its electronic properties are described microscopically within the extended Hubbard model [17], which in the real-space basis, is given as [29] …”

“…Single [1,2], double [3][4][5], triple [6][7][8][9][10][11][12], and quadruple lateral gated quantum dot molecules in GaAlAs/GaAs heterojunctions or with dangling bonds on silicon surface have been demonstrated experimentally [13][14][15] and extensively studied theoretically [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. The capability to localize electrons in artificial lateral quantum dot molecules opens up the possibility of exploring the properties of the 1D Hubbard model, a model of strongly correlated electrons [32][33][34][35][36][37][38].…”

Charged-impurity-induced dephasing of a voltage-controlled coded qubit based on electron spin in a triple quantum dot

“…It follows that the eigenstates of the Hamiltonian have well defined wave vector K and can be written as a linear combination of only configurations with the same K : Figure 1 shows the energy levels of the coded qubit in the absence of impurity. 9,10 The energy levels are labeled by the corresponding eigenvectors ͉K i 0 ͘. In terms of localized configurations, the six highest levels are mostly composed of doubly occupied configurations whereas the three lowest energy levels are mainly composed of singly occupied configurations…”

“…In this work we study the effect of remote charged impurity on the qubit encoded in the two low-energy levels of electrostatically defined triple quantum dot ͑TQD͒ with one-electron spin each. 9,10 A coded qubit controlled by exchange interaction composed of three spins has been proposed by Di Vincenzo et al 11 Its implementation in a triple lateral quantum dot with one electron each has been proposed by some of us in Refs. 9 and 10 and a triple quantum dot molecule with controlled electron numbers has been demonstrated recently.…”

Phonon-Induced Pure Dephasing of Two-Electron Spin States in Vertical Quantum Dot Molecules

“…The carrier-phonon interaction leads to pure dephasing of charge-state superpositions on picosecond timescales. One of the possible solutions to this problem is to use the electron spin degrees of freedom for information storage [1] or as the qubit itself [2][3][4]. Phonon influence on spin states is much weaker than on charge states due to the lack of a direct spin-phonon coupling (an interaction is mediated by the spin-orbit coupling which is weak in QDs and strongly dependent on the magnitude of the magnetic field).…”