AVS 71 Session QS1-TuA: Interdisciplinary Quantum Applications

Quantum information science is limited by the lack of materials that enable precise, rational control over quantum photonic, excitonic, and spin states and other properties of the quantum materials. While DNA nanotechnology offers in principle such control via spatial templating of chromophores, quantum dots, and molecular spin centers with nanometer-scale precision, this capability requires interfacing with silicon-based 2D devices to enable quantum information science with translational impact on devices. Toward this end, we previously demonstrated that programmable DNA templates can position quantum materials such as colloidal quantum dots and rods with nanometer-scale precision for integration with photonic devices through top-down electron beam lithography [1]. Here, we apply this approach to fabricate photonic cavities to control single-photon emissive properties and photonic waveguides for photonic quantum circuits. We additionally demonstrate pathways towards controlling molecular spins and excitons with DNA templates for quantum information science and technology. This scalable approach to templating quantum materials opens new applications to quantum sensing, networking, and simulation, with potential impact on secure communications, medical diagnostics, computing, and beyond.

[1] Luo, X. et al. DNA origami directed nanometer-scale integration of colloidal quantum emitters with silicon photonics. bioRxiv, doi: 10.1101/2025.01.23.634416 (2025).

Favorable optical and spin properties of the V2 silicon vacancy defect in 4H-SiC have made it a promising candidate for quantum technologies. For quantum sensing with defect spins, the contrast in optically-detected magnetic resonance (ODMR) is an important metric, which tends to be rather low (<1%) for V2 ensembles using off-resonant laser excitation. To improve contrast, we resonantly excite the V2 ensembles at low temperatures and compare our findings with off-resonant excitation. Our measurements show a ~90 times improvement for ODMR contrast over the off-resonant case for fairly low resonant excitation. We hypothesize that for a particular wavelength, the resonant laser excites a subset of defects within the ensemble and drives only one of the spin-selective optical transitions for each defect. This leads to a strong spin polarization, contributing to the high readout contrast. To test our hypothesis and further characterize the behavior, we examine the dependence of the contrast on the laser linewidth and the sample temperature. Modulating the resonant laser linewidth up to 1 GHz, corresponding to the splitting of the two optical transitions, results in the contrast decreasing by 50%. As the temperature is increased to 60 K, the contrast decreases and reaches the off-resonant value, presumably due to linewidth broadening. Although the PL signal is 50 times weaker than the off-resonant excitation due to the participation of the defect sub-ensemble, the sensing figure of merit (FoM) is 10 times higher, making the resonant approach still the best choice for sensing at low temperatures. Due to the high readout contrast and reduced laser power requirements, we plan to utilize this resonant technique for wide-field magnetic imaging of quantum materials and devices at low temperatures.

Next-generation quantum technologies demand precise control over the structural and electronic environment of solid-state qubits. Group IV color centers in diamond, particularly tin-vacancy (SnV) defects, have emerged as promising spin-photon interfaces due to their high optical coherence and symmetry-protected electronic states. However, practical deployment of these qubits is limited by low-temperature operational requirements driven by phonon-mediated decoherence.

This presentation will highlight a new synchrotron-enabled experimental platform under development to directly correlate local atomic structure and strain-induced quantum optical response in SnV qubits in diamond. Using micron-resolved high-resolution X-ray diffraction and diffuse scattering at the Advanced Photon Source, combined with integrated cryogenic photoluminescence spectro-microscopy, we are enabling in-situ studies of qubit behavior under extreme uniaxial tensile strain below 2 Kelvin temperatures.

The platform is based on a Joule-Thomson driven cryostat engineered for sub-2K operation, with nanometer positional control and wide-angle X-ray access. Strain engineering leverages enhanced spin-orbit coupling to suppress decoherence pathways, with the ultimate aim of achieving coherent qubit operation at liquid nitrogen temperatures.

This capability will resolve how long-range strain fields, local defect environments, and lattice disorder influence spin coherence and phonon scattering—key mechanisms governing both quantum state lifetimes and optoelectronic coupling. Our approach represents a new paradigm in synchrotron-enabled quantum materials research and paves the way for scalable, strain-tunable quantum devices.