Microwave Control of the Tin-Vacancy Spin Qubit in Diamond with a Superconducting Waveguide

TL;DR

This paper demonstrates enhanced microwave control and extended coherence times of tin-vacancy centers in diamond using superconducting waveguides, advancing their potential for quantum network applications.

Contribution

It introduces the use of superconducting coplanar waveguides for improved microwave control of strained SnV centers, achieving significantly longer coherence times.

Findings

Hahn echo coherence time of 430 microseconds

Extended coherence to 10 milliseconds with dynamical decoupling

Observation of a nearby $^{13}$C spin as a potential quantum memory

Abstract

Group-IV color centers in diamond are promising candidates for quantum networks due to their dominant zero-phonon line and symmetry-protected optical transitions that connect to coherent spin levels. The negatively charged tin-vacancy (SnV) center possesses long electron spin lifetimes due to its large spin-orbit splitting. However, the magnetic dipole transitions required for microwave spin control are suppressed, and strain is necessary to enable these transitions. Recent work has shown spin control of strained emitters using microwave lines that suffer from Ohmic losses, restricting coherence through heating. We utilize a superconducting coplanar waveguide to measure SnV centers subjected to strain, observing substantial improvement. A detailed analysis of the SnV center electron spin Hamiltonian based on the angle-dependent splitting of the ground and excited states is performed. We demonstrate coherent spin manipulation and obtain a Hahn echo coherence time of up to $T_2 = 430\,\mu$s. With dynamical decoupling, we can prolong coherence to $T_2 = 10\,$ms, about six-fold improved compared to earlier works. We also observe a nearby coupling $^{13}\mathrm{C}$ spin which may serve as a quantum memory. This substantiates the potential of SnV centers in diamond and demonstrates the benefit of superconducting microwave structures.