Coherent transfer of singlet-triplet qubit states in an architecture of triple quantum dots

Abstract

We propose two schemes to coherently transfer arbitrary quantum states of the\ntwo-electron singlet-triplet qubit across a chain of 3 quantum dots. The\nschemes are based on electrical control over the detuning energy of the quantum\ndots. The first is a pulse-gated scheme, requiring dc pulses and engineering of\ninter- and intra-dot Coulomb energies. The second scheme is based on the\nadiabatic theorem, requiring time-dependent control of the detuning energy\nthrough avoided crossings at a rate that the system remains in the ground\nstate. We simulate the transfer fidelity using typical experimental parameters\nfor silicon quantum dots. Our results give state transfer fidelities between\n$94.3\\% < \\mathcal{F} < 99.5\\%$ at sub-ns gate times for the pulse-gated scheme\nand between $75.4\\% < \\mathcal{F} < 99.0 \\%$ at tens of ns for the adiabatic\nscheme. Taking into account dephasing from charge noise, we obtain state\ntransfer fidelities between $94.0\\% < \\mathcal{F} < 99.2\\%$ for the pulse-gated\nscheme and between $64.9\\% < \\mathcal{F} < 93.6\\%$ for the adiabatic scheme.\n