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Sinclair, Neil

Publications and source records attributed to Sinclair, Neil.

26 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Optical coherence and energy-level properties of a Tm 3+ -doped LiNbO 3 waveguide at subKelvin temperatures

We characterize the optical coherence and energy-level properties of the 795-nm 3 H 6 to 3 H 4 transition of Tm 3+ in a Ti 4+ :LiNbO 3 waveguide at temperatures as low as 0.65 K. Coherence properties are measured with varied temperature, magnetic field, optical excitation power and wavelength, and measurement timescale. We also investigate nuclear spin-induced hyperfine structure and population dynamics with varying magnetic field and laser excitation power. Except for accountable differences due to different Ti 4+ - and Tm 3+ -doping concentrations, we find that the properties of Tm 3+ :Ti 4+ :LiNbO 3 produced by indiffusion doping are consistent with those of a bulk-doped Tm 3+ :LiNbO 3 crystal measured under similar conditions. Furthermore, our results, which complement previous work in a narrower parameter space, support using rare-earth ions for integrated optical and quantum signal processing.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2021

Illinois Express Quantum Network (IEQNET): metropolitan-scale experimental quantum networking over deployed optical fiber

The Illinois Express Quantum Network (IEQNET) is a program to realize metro-scale quantum networking over deployed optical fiber using currently available technology. IEQNET consists of multiple sites that are geographically dispersed in the Chicago metropolitan area. Each site has one or more quantum nodes (Qnodes) representing the communication parties in a quantum network. Q-nodes generate or measure quantum signals such as entangled photons and communicate the results via standard, classical, means. The entangled photons in IEQNET nodes are generated at multiple wavelengths, and are selectively distributed to the desired users via optical switches. Here we describe the network architecture of IEQNET, including the Internet-inspired layered hierarchy that leverages software-defined-networking (SDN) technology to perform traditional wavelength routing and assignment between the Q-nodes. Specifically, SDN decouples the control and data planes, with the control plane being entirely classical. Issues associated with synchronization, calibration, network monitoring, and scheduling will be discussed. An important goal of IEQNET is demonstrating the extent to which the control plane can coexist with the data plane using the same fiber lines. This goal is furthered by the use of tunable narrow-band optical filtering at the receivers and, at least in some cases, a wide wavelength separation between the quantum and classical channels. We envision IEQNET to aid in developing robust and practical quantum networks by demonstrating metro-scale quantum communication tasks such as entanglement distribution and quantum-state teleportation.

Chung, Joaquin↗
DOE OSTI2020

Cavity electro-optics in thin-film lithium niobate for efficient microwave-to-optical transduction

Linking superconducting quantum devices to optical fibers via microwave-optical quantum transducers may enable large-scale quantum networks. For this application, transducers based on the Pockels electro-optic (EO) effect are promising for their direct conversion mechanism, high bandwidth, and potential for low-noise operation. However, previously demonstrated EO transducers require large optical pump power to overcome weak EO coupling and reach high efficiency. Here, we create an EO transducer in thin-film lithium niobate, a platform that provides low optical loss and strong EO coupling. We demonstrate on-chip transduction efficiencies of up to and of optical pump power. The transduction efficiency can be improved by further reducing the microwave resonator’s piezoelectric coupling to acoustic modes, increasing the optical resonator quality factor to previously demonstrated levels, and changing the electrode geometry for enhanced EO coupling. We expect that with further development, EO transducers in thin-film lithium niobate can achieve near-unity efficiency with low optical pump power.

Holzgrafe, Jeffrey (ORCID:0000000160121451)↗
DOE OSTI2020

Integrated microwave acousto-optic frequency shifter on thin-film lithium niobate

Electrically driven acousto-optic devices that provide beam deflection and optical frequency shifting have broad applications from pulse synthesis to heterodyne detection. Commercially available acousto-optic modulators are based on bulk materials and consume Watts of radio frequency power. Here, we demonstrate an integrated 3-GHz acousto-optic frequency shifter on thin-film lithium niobate, featuring a carrier suppression over 30 dB. Further, we demonstrate a gigahertz-spaced optical frequency comb featuring more than 200 lines over a 0.6-THz optical bandwidth by recirculating the light in an active frequency shifting loop. Our integrated acousto-optic platform leads to the development of on-chip optical routing, isolation, and microwave signal processing.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Non-reciprocal transmission of microwave acoustic waves in nonlinear parity–time symmetric resonators

Acoustic waves are versatile on-chip information carriers that can be used in applications such as microwave filters and transducers. Nonreciprocal devices, in which the transmission of waves is non-symmetric between two ports, are desirable for the manipulation and routing of phonons, but building acoustic non-reciprocal devices is difficult because acoustic systems typically have a linear response. Here, we report non-reciprocal transmission of microwave surface acoustic waves using a nonlinear parity–time symmetric system based on two coupled acoustic resonators in a lithium niobate platform. Furthermore, owing to the strong piezoelectricity of lithium niobate, we can tune the gain, loss and nonlinearity of the system using electric circuitry. Our approach can achieve 10 dB of non-reciprocal transmission for surface acoustic waves at a frequency of 200 MHz, and we use it to demonstrate a one-way circulation of acoustic waves in cascading non-reciprocal devices.

42 ENGINEERING↗
DOE OSTI2020

High-Q suspended optical resonators in 3C silicon carbide obtained by thermal annealing

We fabricate suspended single-mode optical waveguides and ring resonators in 3C silicon carbide (SiC) that operate at telecommunication wavelength, and leverage post-fabrication thermal annealing to minimize optical propagation losses. Annealed optical resonators yield quality factors of over 41,000, which corresponds to a propagation loss of 7 dB/cm, and is a significant improvement over the 24 dB/cm in the case of the non-annealed chip. This improvement is attributed to the enhancement of SiC crystallinity and a significant reduction of waveguide surface roughness, from 2.4 nm to below 1.7 nm. The latter is attributed to surface layer oxide growth during the annealing step. We confirm that the thermo-optic coefficient, an important parameter governing high-power and temperature-dependent performance of SiC, does not vary with annealing and is comparable to that of bulk SiC. Our annealing-based approach, which is especially suitable for suspended structures, offers a straightforward way to realize high-performance 3C-SiC integrated circuits.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗