Beyond the Purcell Effect: Controlling Pure Quantum Dephasing with Spin Noise Metasurfaces

TL;DR

This paper introduces broadband nanophotonic spin noise metasurfaces to control pure quantum dephasing of NV centers, expanding quantum light-matter interaction engineering beyond traditional Purcell effects.

Contribution

It presents a novel approach using ultra-subwavelength spin noise metasurfaces for broadband control of low-frequency dephasing, demonstrated with lithographically defined metasurfaces and NV centers.

Findings

Modified NV pure dephasing dynamics observed near different metasurfaces.

Metasurface-controlled dephasing isolated from other mechanisms.

Established a new method for engineering quantum light-matter interactions.

Abstract

One central theme in quantum photonics is tailoring the interactions between atoms/spins and their electromagnetic (EM) environments. Considerable effort has focused on engineering spontaneous emission by shaping EM environments, known as the Purcell effect. However, photonic environment control of pure dephasing, which is a complementary paradigm of non-unitary atom/spin couplings with EM environments, remains largely unexplored. Here, we introduce a nanophotonic approach to modify qubit pure dephasing dynamics. Unlike Purcell engineering that tailors photonic environments at qubit resonance frequencies (typically optical/near-infrared), we develop ultra-subwavelength spin noise metasurfaces for efficient broadband control of low-frequency (e.g., $\sim$MHz) photonic environments far off-resonant with atoms/spins for dephasing engineering. We experimentally demonstrate our approach using lithographically defined CoFeB metasurfaces and shallow nitrogen-vacancy (NV) centers in diamond. Instead of modified spontaneous emission, we observe modified NV pure dephasing dynamics near different spin noise metasurfaces. We further isolate metasurface-controlled dephasing from other dephasing mechanisms (e.g., spin bath) by measuring the NV ensemble dephasing noise spectrum with dynamical decoupling spectral decomposition techniques. Our results establish a new frontier in engineering quantum light-matter interactions with nanophotonic structures.