Control of single-spin decoherence by dynamical decoupling and spin bath manipulation

G. de Lange, Toeno van der Sar, Machiel Blok +3 more

Nan Zhao, Wei Hua Yang, Sai-Wah Ho +5 more

G. de Lange, Toeno van der Sar, Machiel Blok +3 more

Understanding and mitigating decoherence is a key challenge for quantum science and technology. The main source of decoherence for solid-state spin systems is the uncontrolled spin bath environment. Here, we demonstrate quantum control of a mesoscopic spin bath in diamond at room temperature that is composed of electron spins of substitutional nitrogen impurities. The resulting spin bath dynamics are probed using a single nitrogen-vacancy (NV) centre electron spin as a magnetic field sensor. We exploit the spin bath control to dynamically suppress dephasing of the NV spin by the spin bath. Furthermore, by combining spin bath control with dynamical decoupling, we directly measure the coherence and temporal correlations of different groups of bath spins. These results uncover a new arena for fundamental studies on decoherence and enable novel avenues for spin-based magnetometry and quantum information processing.

Nan Zhao, Sai-Wah Ho, Ren‐Bao Liu

We theoretically study the decoherence and the dynamical decoupling control of nitrogen vacancy center electron spins in high-purity diamond, where the hyperfine interaction with ${}^{13}$C nuclear spins is the dominating decoherence mechanism. The decoherence is formulated as the entanglement between the electron spin and the nuclear spins, which is induced by nuclear spin bath evolution conditioned on the electron spin state. The nuclear spin bath evolution is driven by elementary processes such as single spin precession and pairwise flip flops. The importance of different elementary processes in the decoherence depends on the strength of the external magnetic field.

Wen-Long Ma, Gary Wolfowicz, Nan Zhao +3 more

Central spin decoherence caused by nuclear spin baths is often a critical issue in various quantum computing schemes, and it has also been used for sensing single-nuclear spins. Recent theoretical studies suggest that central spin decoherence can act as a probe of many-body physics in spin baths; however, identification and detection of many-body correlations of nuclear spins in nanoscale systems are highly challenging. Here, taking a phosphorus donor electron spin in a 29Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in decoherence of the central spin under multiple-pulse dynamical decoupling control. We demonstrate that under control by an odd or even number of pulses, the central spin decoherence is principally caused by second- or fourth-order nuclear spin correlations, respectively. This study marks an important step toward studying many-body physics using spin qubits. Detecting many-body correlations is a long-standing challenge in many-body physics. By studying their effects on the decoherence of the central spin under dynamical decoupling, Ma et al.provide an experimental demonstration of detection of many-body correlations in nanoscale nuclear spin bath.

Ren‐Bao Liu