Telecom-Band Quantum Optics with Ytterbium Atoms and Silicon Nanophotonics

Abstract

Wavelengths in the telecommunication window (∼ 1.25 − 1.65 µm) are ideal for quantum communication due to low transmission loss in fiber networks. To realize quantum networks operating at these wavelengths, long-lived quantum memories that couple to telecom-band photons with high efficiency need to be developed. We propose coupling neutral ytterbium atoms, which have a strong telecom-wavelength transition, to a silicon photonic crystal cavity. Specifically, we consider the 3 P0 ↔ 3 D1 transition in neutral 171 Yb to interface its long-lived nuclear spin in the metastable 3 P0 'clock' state with a telecom-band photon at 1.4 µm. We show that Yb atoms can be trapped using a short wavelength (≈ 470 nm) tweezer at a distance of 350 nm from the silicon photonic crystal cavity. At this distance, due to the slowly decaying evanescent cavity field at a longer wavelength, we obtain a single-photon Rabi frequency of g/2π ≈ 100 MHz and a cooperativity of C ≈ 47 while maintaining a high photon collection efficiency into a single mode fiber. 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.

An Atomic-Array Optical Clock with Single-Atom Readout

“…In parallel, single-atom detection and control techniques have propelled quantum simulation and computing applications based on trapped atomic arrays; in particular, ion traps [10], optical lattices [11], and optical tweezers [12,13]. Integrating such techniques into an optical clock would provide atom-by-atom error evaluation, feedback, and thermometry [14]; facilitate quantum metrology applications, such as quantum-enhanced clocks [15][16][17][18] and clock networks [19]; and enable novel quantum computation, simulation, and communication architectures that require optical clock state control combined with single atom trapping [20][21][22].…”

Microwave-to-optical conversion via four-wave mixing in a cold ytterbium ensemble

“…Finally, our system could be extended to 171 Yb, an isotope with nuclear spin I = 1/2, to introduce a long-lived quantum memory. This could enable entanglement between a microwave photon and the nuclear spin by the same mechanism as recently proposed for an optical photon [22], and could provide a platform for integrating a quantum memory with superconducting quantum circuits. Such a possibility showcases the potential of using cold alkaline-earth atoms, in which nuclear coherence times far exceed that of solid-state platforms.…”

“…The fourlevel cycle operates in a diamond configuration whose lowest level is the 'clock' state 3 P 0 of lifetime > 20 s, which can be accessed from the ground state 1 S 0 by either direct excitation [23,24] or by multi-photon excitation via 3 P 1 [25] (see Ref. [22] for a more complete level diagram and Appendix II.A for analysis of the branching ratios to the 3 P J manifold). The diamond configuration of the transducer cycle is shown in Fig.…”

“Tweezer Clock” Offers New Possibilities in Timekeeping

“…In addition, AOCs offer an advanced toolset for generation and detection of entanglement to reach beyond standard quantum limit operation-either through cavities [16,46] or Rydberg excitation [15]-and for implementing quantum clock networks [19]. Furthermore, the demonstrated techniques provide a pathway for quantum computing and communication with neutral alkaline-earth-like atoms [8,20,22]. Finally, features of atomic array clocks -such as experimental simplicity, short dead time, and three-dimensional confinement-make these systems attractive candidates for robust portable clock systems and space-based missions [31].…”

“…In parallel, single-atom detection and control techniques have propelled quantum simulation and computing applications based on trapped atomic arrays; in particular, ion traps [10], optical lattices [11], and optical tweezers [12,13]. Integrating such techniques into an optical clock would provide atom-by-atom error evaluation, feedback, and thermometry [14]; facilitate quantum metrology applications, such as quantumenhanced clocks [15][16][17][18] and clock networks [19]; and enable novel quantum computation, simulation, and communication architectures that require optical-clock-state control combined with single-atom trapping [20][21][22].…”