Coupling molecular spin states by photon-assisted tunneling

TL;DR

This paper demonstrates that microwave irradiation can induce spin-flip tunneling transitions in artificial molecules, enabling detailed spectroscopy and potential quantum control of spin states through spin-orbit interactions.

Contribution

It reveals that microwaves can excite spin-changing tunneling transitions in artificial molecules, expanding the understanding of spin dynamics and control in nanoscale quantum systems.

Findings

Microwave-induced spin-flip tunneling transitions observed.

Spin-orbit interaction identified as the main mechanism.

Potential for full quantum control of two-spin systems.

Abstract

Artificial molecules containing just one or two electrons provide a powerful platform for studies of orbital and spin quantum dynamics in nanoscale devices. A well-known example of these dynamics is tunneling of electrons between two coupled quantum dots triggered by microwave irradiation. So far, these tunneling processes have been treated as electric dipole-allowed spin-conserving events. Here we report that microwaves can also excite tunneling transitions between states with different spin. In this work, the dominant mechanism responsible for violation of spin conservation is the spin-orbit interaction. These transitions make it possible to perform detailed microwave spectroscopy of the molecular spin states of an artificial hydrogen molecule and open up the possibility of realizing full quantum control of a two spin system via microwave excitation.