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

TL;DR

This paper introduces two methods for coherently transferring singlet-triplet qubit states across a triple quantum dot chain, demonstrating high fidelity with realistic silicon quantum dot parameters.

Contribution

It proposes and simulates two novel schemes for quantum state transfer in triple quantum dots, one pulse-gated and one adiabatic, with detailed fidelity analysis.

Findings

Pulse-gated scheme achieves 94.3% to 99.5% fidelity at sub-ns times.

Adiabatic scheme achieves 75.4% to 99.0% fidelity at tens of ns.

Fidelity remains high when accounting for charge noise dephasing.

Abstract

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