Direct transfer of two-electron quantum states in ac-driven triple quantum dots

Abstract

Preparation and transfer of quantum states is a fundamental task in quantum information. We propose a protocol to prepare a state in the left and center quantum dots of a triple dot array and transfer it directly to the center and right dots. Initially the state in the left and center dots is prepared combining the exchange interaction and magnetic field gradients. Once in the desired state, ac gate voltages in the outer dots are switched on, allowing to select a given photoassisted long-range path and to transfer the prepared state directly from one edge to the other with high fidelity. We investigate the effect of charge noise on the protocol and propose a configuration in which the transfer can be performed with high fidelity. Our proposal can be experimentally implemented and is a promising avenue for transferring quantum states between two spatially separated two-level systems.arXiv:1810.06517v2 [cond-mat.mes-hall]

Dynamical second-order noise sweetspots in resonantly driven spin qubits

“…This could produce a new set of dynamical sweetspots at large values of the ac voltage, in a similar way to the case of Ref. [53]. However, for the parameters considered here this results in a set of sidebands which are almost resonant, breaking the conditions for the cotunneling approximation.…”

“…If the states with double occupancy are sufficiently separated in energy from the states in Q, we may perform a time-dependent Schrieffer-Wolff transformation [53,74] (SWT) with respect to H T,I (t) in order to obtain an effective Hamiltonian for the low energy subspace Q, with virtual tunneling as the leading order of perturbation, given by ĤSW (t) = e Υ(t) ĤI (t) e − Υ(t) − i ∂ t Υ (t), where Υ (t) = σ s βα (t) ĉ † α,σ ĉβ,σ is an anti-Hermitian operator and the s αβ (t) satisfy…”

“…In the recent years, several works [46][47][48][49][50] have devel-oped the idea of employing ac gates to engineer noise sweetspots [51,52] in which the decoherence time due to noise is significantly increased. A recent paper [53] shows how an ac voltage can induce a dynamical sweetspot due to sideband interference, suppressing the coupling to the electric environment. In this work, we study how to employ ac gates to induce dynamical sweetspots in a qubit defined on a double quantum dot (DQD).…”

Dynamical second-order noise sweetspots in resonantly driven spin qubits

“…In the recent years, several works [42][43][44][45][46] have developed the idea of employing ac gates to engineer noise sweetspots [47,48] in which the decoherence time due to noise is significantly increased. A recent paper [49] shows how an ac voltage can induce a dynamical sweetspot due…”

Designing adiabatic time evolution from high-frequency bichromatic sources

“…Applying periodic perturbations has been shown to be a versatile tool to manipulate physical systems. For instance, they allow one to control spin qubits in quantum dots [7][8][9][10][11], or to induce new electronic, dynamical, and topological properties [12][13][14][15][16]. These works typically consider monochromatic driving, although bichromatic fields have been used in a few occasions [17][18][19][20], showing that their potential has not been fully explored.…”