Complete coherent control of spin qubits in self-assembled InAs quantum dots under oblique magnetic fields

TL;DR

This paper demonstrates complete coherent control of a single spin qubit in InAs quantum dots using oblique magnetic fields, offering a versatile alternative to traditional geometries for quantum information processing.

Contribution

It introduces the use of oblique magnetic fields for full spin qubit control, expanding the design options for quantum dot-based quantum computing.

Findings

Achieved Rabi oscillations and Ramsey fringes in oblique field configuration.

Demonstrated arbitrary single-qubit rotations under oblique magnetic fields.

Compared control in oblique geometry with conventional Voigt geometry.

Abstract

We demonstrate complete coherent control of a single spin qubit confined in a self-assembled InAs negatively charged quantum dot subjected to an Oblique magnetic field, and directly compare this regime with the conventional Voigt geometry. In the Oblique-field configuration, the groundstate spin eigenstates are found to be unequal superpositions of the bare electron spin, with their composition tunable via the orientation of the applied field. This tunable spin mixing provides an additional degree of freedom to engineer the spin basis and associated optical couplings in the charged quantum dot system. Although this geometry has a distinct structure with important implications, it provides a regime in which we can fully and coherently control the tailored spin qubit. We observe Rabi oscillations and Ramsey fringes, and demonstrate arbitrary single-qubit rotations, enabling a direct comparison with the Voigt case. Our results establish that spin-qubit control does not necessarily require a pure Voigt geometry and can instead be achieved under Oblique magnetic fields. This relaxes constraints on device and field alignment and offers a versatile route to design and optimize quantum information processing architectures in semiconductor quantum dots.