Preeti Ovartchaiyapong

Dynamic strain-mediated coupling of a single diamond spin to a mechanical resonator

The development of hybrid quantum systems is central to the advancement of emerging quantum technologies, including quantum information science and quantum-assisted sensing. The recent demonstration of high-quality single-crystal diamond resonators has led to significant interest in a hybrid system consisting of nitrogen–vacancy centre spins that interact with the resonant phonon modes of a macroscopic mechanical resonator through crystal strain. However, the nitrogen–vacancy spin–strain interaction has not been well characterized. Here, we demonstrate dynamic, strain-mediated coupling of the mechanical motion of a diamond cantilever to the spin of an embedded nitrogen–vacancy centre. Via quantum control of the spin, we quantitatively characterize the axial and transverse strain sensitivities of the nitrogen–vacancy ground-state spin. The nitrogen–vacancy centre is an atomic scale sensor and we demonstrate spin-based strain imaging with a strain sensitivity of 3 × 10−6 strain Hz−1/2. Finally, we show how this spin-resonator system could enable coherent spin–phonon interactions in the quantum regime.

High quality factor single-crystal diamond mechanical resonators

Single-crystal diamond is a promising material for microelectromechanical systems (MEMs) because of its low mechanical loss, compatibility with extreme environments, and built-in interface to high-quality spin centers. But its use has been limited by challenges in processing and growth. We demonstrate a wafer bonding-based technique to form diamond on insulator, from which we make single-crystal diamond micromechanical resonators with mechanical quality factors as high as 338 000 at room temperature. Variable temperature measurements down to 10 K reveal a nonmonotonic dependence of quality factor on temperature. These resonators enable integration of single-crystal diamond into MEMs technology for classical and quantum applications.

Topical review: spins and mechanics in diamond

There has been rapidly growing interest in hybrid quantum devices involving a solid-state spin and a macroscopic mechanical oscillator. Such hybrid devices create exciting opportunities to mediate interactions between disparate qubits and to explore the quantum regime of macroscopic mechanical objects. In particular, a system consisting of the nitrogen-vacancy defect center in diamond coupled to a high quality factor mechanical oscillator is an appealing candidate for such a hybrid quantum device, as it utilizes the highly coherent and versatile spin properties of the defect center. In this paper, we will review recent experimental progress on diamond-based hybrid quantum devices in which the spin and orbital dynamics of single defects are driven by the motion of a mechanical oscillator. In addition, we discuss prospective applications for this device, including long range, phonon-mediated spin-spin interactions, and phonon cooling in the quantum regime. We conclude the review by evaluating the experimental limitations of current devices and identifying alternative device architectures that may reach the strong coupling regime.

Nanomechanical Sensing Using Spins in Diamond

Nanomechanical sensors and quantum nanosensors are two rapidly developing technologies that have diverse interdisciplinary applications in biological and chemical analysis and microscopy. For example, nanomechanical sensors based upon nanoelectromechanical systems (NEMS) have demonstrated chip-scale mass spectrometry capable of detecting single macromolecules, such as proteins. Quantum nanosensors based upon electron spins of negatively charged nitrogen-vacancy (NV) centers in diamond have demonstrated diverse modes of nanometrology, including single molecule magnetic resonance spectroscopy. Here, we report the first step toward combining these two complementary technologies in the form of diamond nanomechanical structures containing NV centers. We establish the principles for nanomechanical sensing using such nanospin-mechanical sensors (NSMS) and assess their potential for mass spectrometry and force microscopy. We predict that NSMS are able to provide unprecedented AC force images of cellular biomechanics and to not only detect the mass of a single macromolecule but also image its distribution. When combined with the other nanometrology modes of the NV center, NSMS potentially offer unparalleled analytical power at the nanoscale.

Strain Coupling of a Mechanical Resonator to a Single Quantum Emitter in Diamond

The recent maturation of hybrid quantum devices has led to significant enhancements in the functionality of a wide variety of quantum systems. In particular, harnessing mechanical resonators for manipulation and control has expanded the use of two-level systems in quantum information science and quantum sensing. In this letter, we report on a monolithic hybrid quantum device in which strain fields associated with resonant vibrations of a diamond cantilever dynamically control the optical transitions of a single nitrogen-vacancy (NV) defect center in diamond. We quantitatively characterize the strain coupling to the orbital states of the NV center, and with mechanical driving, we observe NV-strain couplings exceeding 10 GHz. Furthermore, we use this strain-mediated coupling to match the frequency and polarization dependence of the zero-phonon lines of two spatially separated and initially distinguishable NV centers. The experiments demonstrated here mark an important step toward engineering a quantum device capable of realizing and probing the dynamics of non-classical states of mechanical resonators, spin-systems, and photons.