All-silicon quantum photonics using T centers

Non-technical summary

Optically active spin qubits are the fundamental building blocks of quantum networks and distributed quantum computers. This project aims to significantly advance quantum information science by developing optically active quantum bits (qubits) in silicon, allowing us to utilize the existing vast infrastructure for silicon processing to develop scalable quantum devices.

The program focuses on a color center called the T center. This optically active spin qubit can be directly engineered in silicon, enabling the convergence of quantum photonics and silicon photonics in a single material platform.

Our research will develop the fundamental science and device physics necessary to generate scalable spin qubits based on T centers for large-scale quantum photonic devices. We will enhance the T center's optical properties through nanophotonic integration to achieve an efficient interface between light and spin. We will demonstrate key quantum operations including indistinguishable single photon emission, spin initialization, and coherent control of electron and nuclear spins, paving the way to entangle spins over long distances using fiber-optic channels.

We will also use advanced noise spectroscopy to study the fundamental noise processes that limit spin coherence times, and establish advanced dynamical decoupling pulse sequences that can extend them by orders of magnitude.

Our ultimate goal is to create repeatable arrays of Elementary Memory Units (EMUs) using T centers. EMUs combine quantum memory with photonics, electrical tuning, and microwave control to form a self-contained building block for future quantum networks and distributed quantum processors. Using these EMUs, the project will explore methods to generate and distribute entanglement between T centers across different locations, including within the MARQI network, developed by the PI to connect quantum nodes at the University of Maryland campus, neighboring research labs, and quantum startups.

The program will have a wide-ranging impact on multiple fields including integrated photonics, quantum optics, and spin-based information processing. It will also contribute significantly to education and workforce development in quantum technology by supporting graduate and undergraduate students, as well as developing educational modules for the Quantum Atlas, an interactive resource aimed at enhancing public understanding of quantum science.

Furthermore, the project will offer research opportunities to students through the UMD GRAD-MAP program. Technical summary

Optically active spin qubits are the fundamental building blocks of quantum networks and distributed quantum computers. Integrating these qubits into silicon, a highly scalable integrated photonics platform, would constitute a significant breakthrough in quantum information processing. This program will develop a new class of optically active spin qubits in silicon that exhibit exceptional optical properties combined with long spin coherence times.

Our research will concentrate on the T center, a silicon color center that can exhibit efficient radiative emission within the telecom band along with the capability to store quantum information in both electron and nuclear spin. We will combine T center qubits with nanophotonic engineering and microwave excitation to demonstrate the core operations required for quantum applications: indistinguishable single photon emission, spin initialization, coherent electron and nuclear spin control, and single-shot readout.

We will leverage these capabilities to create repeatable arrays of Elementary Memory Units (EMUs) based on T centers that can serve as the building blocks of distributed quantum information processors. Furthermore, we will elucidate the fundamental properties of the T center spin qubit through noise spectroscopy and implement optimized dynamical decoupling pulse sequences to increase spin coherence times by orders of magnitude.

Finally, we will develop new methods to generate spin-photon entanglement optimized for T centers that leverage frequency and time-bin photonic qubit.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.