Complete readout of two-electron spin states in a double quantum dot

TL;DR

This paper presents a method for complete and efficient readout of two-electron spin states in a double quantum dot, leveraging fast tunability and repetitive measurements to distinguish all spin configurations.

Contribution

It introduces a protocol combining Pauli spin blockade with rapid tuning to achieve full spin state readout, advancing scalable spin qubit technology.

Findings

Successful demonstration of complete spin state readout

Fast tunability enables rapid measurement sequences

Protocol distinguishes all four two-electron spin states

Abstract

We propose and demonstrate complete spin state readout of a two-electron system in a double quantum dot probed by an electrometer. The protocol is based on repetitive single shot measurements using Pauli spin blockade and our ability to tune on fast timescales the detuning and the interdot tunnel coupling between the GHz and sub-Hz regime. A sequence of three distinct manipulations and measurements allows establishing if the spins are in S, Tzero, Tplus or Tminus state. This work points at a procedure to reduce the overhead for spin readout, an important challenge for scaling up spin qubit platforms.