Ultrafast universal quantum control of a quantum-dot charge qubit using Landau–Zener–Stückelberg interference

TLDR

Universal qubit control must occur on timescales much shorter than the coherence time, yet scaling ultrafast optical methods to many qubits remains challenging. The technique, performed in a solid‑state architecture, is encoding‑agnostic and promises broader applicability. The authors achieve complete picosecond‑scale control of a quantum‑dot charge qubit, observing tunable dynamics that agree with Landau–Zener–Stückelberg interference and demonstrating the feasibility of a full set of all‑electrical single‑qubit operations.

Abstract

A basic requirement for quantum information processing is the ability to universally control the state of a single qubit on timescales much shorter than the coherence time. Although ultrafast optical control of a single spin has been achieved in quantum dots, scaling up such methods remains a challenge. Here we demonstrate complete control of the quantum-dot charge qubit on the picosecond scale [corrected], orders of magnitude faster than the previously measured electrically controlled charge- or spin-based qubits. We observe tunable qubit dynamics in a charge-stability diagram, in a time domain, and in a pulse amplitude space of the driven pulse. The observations are well described by Landau-Zener-Stückelberg interference. These results establish the feasibility of a full set of all-electrical single-qubit operations. Although our experiment is carried out in a solid-state architecture, the technique is independent of the physical encoding of the quantum information and has the potential for wider applications.