<title>Nutation effect in an ensemble of quantum dots</title>

Photon-assisted conditionality for double-dot charge qubits in a single-mode cavity

“…The inversion of population of logical states is equivalent to the NOT operation. Its successful implementation in a single-electron DQD requires meeting several conditions, as was found earlier [22][23][24][25][26][27]. First, it is necessary to tune the energies of excited states |A1 and |B1 close to each other or, more generally, to minimize their energy difference relative to the tunnel coupling, | 0 | V 0 .…”

“…In analogy to Refs. [22][23][24][25][26][27], we identify the logical qubit states with the DQD ground states: |0 ≡ |A0 and |1 ≡ |B0 . In order to protect the qubit in the absence of the pulse from unwanted evolution (optical transition and/or level shift) caused by the cavity photon one has to choose (i) the frequency detunings to be large compared to the coupling coefficients, |g A(B) | |δ A(B)m |, and (ii) the tunneling to be small compared to the excited state energy difference, V m | m |.…”

“…An alternative strategy for the charge qubit design and control was proposed by Openov [22] and developed in * tsukanov@ftian.ru papers [23][24][25][26][27] by later researchers. In his proposal, the qubit logical states are presented by electron orbital states localized in the conduction band of a symmetric double quantum dot (DQD).…”

Indirect Coupling in a Cluster of Quantum-Dot-Based Charge Qubits

“…In contrast to conventional representation of logical states 0 and 1 of the charge qubit by low-lying single-electron orbital states of a double quantum dot (DQD), [5][6][7][8][9][10][11][12][13][14][15] we use the p x and p y states (hereafter, x and y states) of a twodimension single quantum dot (QD) to encode quantum information whereas the QD ground state g plays role of an intermediate state. The electromagnetic field taken in the form of two resonant laser pulses each polarized along x or y axes, E = E x e x cos x t + E y e y cos y t , drives the electron transitions between logical and intermediate states Indirect Coupling in a Cluster of Quantum-Dot-Based Charge Qubits Tsukanov resulting in a desired final qubit state (Fig.…”