Negative spin exchange in a multielectron quantum dot

Abstract

By operating a one-electron quantum dot (fabricated between a multielectron dot and a one-electron reference dot) as a spectroscopic probe, we study the spin properties of a gate-controlled multielectron GaAs quantum dot at the transition between odd and even occupation number. We observe that the multielectron groundstate transitions from spin-1/2-like to singlet-like to triplet-like as we increase the detuning towards the next higher charge state. The sign reversal in the inferred exchange energy persists at zero magnetic field, and the exchange strength is tunable by gate voltages and in-plane magnetic fields. Complementing spin leakage spectroscopy data, the inspection of coherent multielectron spin exchange oscillations provides further evidence for the sign reversal and, inferentially, for the importance of non-trivial multielectron spin exchange correlations.

8 pages, including 4 main figures and 2 supplementary figurures

References in corpus (9)

• Coherent control of a single electron spin with electric fields
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• Prospects for Spin-Based Quantum Computing
• Electrometry Using Coherent Exchange Oscillations in a Singlet-Triplet-Qubit
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Cited by in corpus (2)

• Crosstalk error correction through dynamical decoupling of single-qubit gates in capacitively coupled singlet-triplet semiconductor spin qubits
• Extended orbital modeling of spin qubits in double quantum dots