Coherent control of spin chains in graphene nanostructures

Introduction

Elementary nuclear and electronic spins are called to be key components in the second quantum revolution. Their atomic-scale integration into scalable platforms with tunable interactions is a demand that I will address in CONSPIRA by synthesizing graphene architectures with interacting spin chains, using customized on-surface reactions of organic precursors, and by controlling their quantum state through microwave spectroscopies.

Vision

I envision the formation of collective magnetic states through the assembly of interacting electronic and nuclear spins in periodic arrays with atomically precise spacings. Through rational design and synthesis strategies, we will tune spin interactions via the graphene host and hyperfine coupling, with the goal of bringing the quantum state of the arrays into different regimes of energy, coherence, and topology.

Experimental Techniques

To access the broad energy range of such multiscale interacting systems and to probe its quantum dynamics, we will combine two antagonist experimental techniques:

1. Scanning Tunnelling Microscopy (STM)
2. Cavity Quantum Electrodynamics (QED)

This will be realized by incorporating superconducting coplanar waveguide resonators (CWRs) as the substrate of a low temperature STM.

QED Techniques

We will use QED techniques to couple the resonant states of spin chains with microwave photons of the resonator, while the STM tip acts as a local gate. The MHz and picometer resolution of this new type of spectrometer will enable us to study the quantum coherence of the spin arrays and undertake the coherent control of distant nuclear states entangled through the electronic spin system, a potential system for QED-based quantum computation.

Conclusion

CONSPIRA will provide a new platform for quantum spins and methods to address and manipulate their coherent state. The combination of QED and STM represents a ground-breaking experimental development, which is called to boost studies of general correlated phenomena in condensed matter physics.