Manipulation of qubits in non-orthogonal collective storage modes

TL;DR

This paper analyzes how to transfer, store, and manipulate multiple quantum bits in non-orthogonal collective modes of a large spin ensemble, with a focus on quantum dots, expanding quantum memory capabilities.

Contribution

It introduces methods for storing and manipulating several independent qubits in non-orthogonal modes of an ensemble, even when modes are not perfectly orthogonal.

Findings

Protocols for quantum state transfer between electron and nuclear spins.

Analysis applicable to various physical systems.

Potential for multi-qubit quantum memory in non-orthogonal modes.

Abstract

We present an analysis of transfer of quantum information between the collective spin degrees of freedom of a large ensemble of two-level systems and a single central qubit. The coupling between the central qubit and the individual ensemble members may be varied and thus provides access to more than a single storage mode. Means to store and manipulate several independent qubits are derived for the case where the variation in coupling strengths does not allow addressing of orthogonal modes of the ensemble. While our procedures and analysis may apply to a number of different physical systems, for concreteness, we study the transfer of quantum states between a single electron spin and an ensemble of nuclear spins in a quantum dot.