We present photonic crystal cavities that enable strong atom-photon coupling at telecom wavelengths, providing a scalable interface for distributed quantum technologies. Additionally, we present progress on metasurfaces for generating in situ optical tweezer arrays.
Wavelengths in the telecommunication window (ca.1.25--1.65 $\ensuremath{\mu}$m) are ideal for quantum communication, due to the low transmission loss in optical-fiber networks. To realize quantum networks operating at these wavelengths, we need long-lived quantum memories that couple efficiently to telecom-band photons. This study proposes using optical tweezers to couple neutral ytterbium atoms, which have a strong telecom-wavelength transition, to a silicon photonic-crystal cavity. The combination of high system efficiency, telecom-band operation, and long coherence times makes this platform well suited for quantum optics on a silicon chip and long-distance quantum communication.
In this Invited Paper, we will summarize our vision for quantum networks based on arrays of individual neutral atoms. With a photonic interface such as an optical cavity, some atoms in the array – the “communication” qubits – can establish remote entanglement while others – the “data” qubits – are used for large-scale quantum information processing or for quantum-enhanced metrology via an atomic clock transition. Deterministic gates within the array will enable operations and algorithms that are distributed among all the qubits in two or more nodes. Additionally, we will discuss our efforts to realize this vision with arrays of ytterbium-171 atoms in optical tweezers, in which telecom-band photons can be directly entangled with nuclear spin qubits without the need for wavelength conversion.
The realization of an efficient quantum optical interface for multi-qubit systems is an outstanding challenge in science and engineering. Using two atoms in individually controlled optical tweezers coupled to a nanofabricated photonic crystal cavity, we demonstrate entanglement generation, fast nondestructive readout, and full quantum control of atomic qubits. The entangled state is verified in free space after being transported away from the cavity by encoding the qubits into long-lived states and using dynamical decoupling. Our approach bridges quantum operations at an optical link and in free space with a coherent one-way transport, potentially enabling an integrated optical interface for atomic quantum processors.