The Orion Artemis II Optical Communications System (informally, Optical to Orion (O2O)) demonstration will showcase standards-compliant High Photon Efficiency (HPE) optical communications for the first time on a crewed cislunar mission with Artemis II. In addition to the high data rate capability afforded by the optical signal, O2O uses the optical signal to enable a high-precision, synchronous, two-way telemetry ranging system for time of flight (ToF) measurement. In this paper we will describe the ToF system used for O2O, from the system architecture and algorithms, to simulations of predicted performance, and finally laboratory experiments of the system over several kilometers of fiber. We additionally describe a calibration technique in the ground terminal that eliminates the need for the measurement of multiple independent paths and test equipment delays. We show that the system enables high precision (< $100$ ps) high accuracy (< $1$ ns) ranging estimation over a wide variety of conditions.

Photon-counting optical receivers have the best sensitivity but are practically limited to relatively low data rates < ~1 Gbit/s. Here, we present technologies that can extend sensitive photon-counting-performance into the 100 Gbit/s regime and beyond.

Distributing quantum information between remote systems will necessitate the integration of emerging quantum components with existing communication infrastructure. This requires understanding the channel-induced degradations of the transmitted quantum signals, beyond the typical characterization methods for classical communication systems. Here we report on a comprehensive characterization of a Boston-Area Quantum Network (BARQNET) telecom fiber testbed, measuring the time-of-flight, polarization, and phase noise imparted on transmitted signals. We further design and demonstrate a compensation system that is both resilient to these noise sources and compatible with integration of emerging quantum memory components on the deployed link. These results have utility for future work on the BARQNET as well as other quantum network testbeds in development, enabling near-term quantum networking demonstrations and informing what areas of technology development will be most impactful in advancing future system capabilities.

A multi-mode photon-counting optical receiver was designed and tested for the NASA Orion Artemis II Optical Communications System downlink. The receiver achieved error-free communications from 20 Mb/s to 267 Mb/s with single-photon-level sensitivity.

We demonstrate electro-optic modulation up to 15GHz (3dB bandwidth) in a silicon nitride ring resonator by electrically poling the silicon nitride at a high temperature to engineer an electro-optic effect.

Precision synchronization is vital for robust long-distance quantum networking over fiber and free-space channels for which high-fidelity entanglement swapping between separate sources via an optical Bell state measurement requires temporal overlap of photonic qubits arriving from either source. This challenge is particularly distinct in satellite-based entanglement distribution in which relative motion, channel effects, and propagation delay must be addressed. This work presents a precision synchronization method for free space entanglement distribution, and reports on risk reduction testing in a quantum networking testbed at MIT Lincoln Laboratory. Primary consideration is for a dual-uplink architecture in which photons from entanglement sources at two ground locations interact in an optical Bell-state measurement implemented on a satellite in a low-earth orbit. The control approach uses independent entanglement sources at each ground location supplemented with a synchronization signal for feedback control from a timing discriminant measured at the spacecraft. The approach is being implemented in a laboratory testbed using 1-GHz repetition rate 1550-nm band entanglement sources generating ~10-MHz source entanglement rates with few-ps photon pulse lengths. The paper describes both fundamental architectural considerations and practical implementation details.

The Orion Artemis II Optical Communications (O2O) system will demonstrate the operational utility of laser communications for the first crewed Artemis mission scheduled to launch next year. O2O will provide an optical link with data rates up to 260 Mbps return from the moon and up to 20 Mbps forward to the moon. The optical link employs a Serially Concatenated Pulse Position Modulation (SCPPM) communications signal, compliant with the Consultative Committee for Space Data Systems (CCSDS) standard, and a modulated uplink beacon for acquisition and collaborative tracking. O2O employs optical ground stations located at the White Sands Complex (WSC) and Table Mountain Facility (TMF) to support the Earth end of the link. We describe interface testing performed between the space and ground terminals to verify the physical layer communication and beacon signals.

We designed and built two polarization entanglement sources optimized for high-rate quantum networking under pump power constraints. We demonstrated entanglement swapping between the sources.

We investigate entanglement source synchronization using a forwarded-pump signal sent over a 3.2-km free-space retro-reflected link. Results show sub-picosecond alignment between the sources. The paper considers several fundamental and practical aspects of this approach.

We propose a means for synchronizing picosecond-class photon generation at a Bell State Measurement device attempting to perform entanglement swapping with received photons that have been transmitted through the atmosphere from a moving platform.

Quantum low probability of intercept transmits ciphertext in a way that prevents an eavesdropper possessing the decryption key from recovering the plaintext. It is capable of Gbps communication rates on optical fiber over metropolitan-area distances. © 2019 The Author(s)

One-way noise across a 42-km deployed optical fiber link is measured using two different techniques employing referenced mode-locked lasers. We compare the two techniques and assess their suitability for stabilizing the fiber for quantum networks.

Noise imparted to an optical signal propagating along a 42-km deployed optical fiber link is measured using two different techniques employing referenced mode-locked lasers. We compare the two techniques and assess their suitability for stabilizing the fiber link for quantum networks.

Photonic integrated circuits (PICs) provide a compact and stable platform for quantum photonics. Here we demonstrate a silicon photonics quantum key distribution (QKD) transmitter in the first high-speed polarization-based QKD field tests. The systems reach composable secret key rates of 950 kbps in a local test (on a 103.6-m fiber with a total emulated loss of 9.2 dB) and 106 kbps in an intercity metropolitan test (on a 43-km fiber with 16.4 dB loss). Our results represent the highest secret key generation rate for polarization-based QKD experiments at a standard telecom wavelength and demonstrate PICs as a promising, scalable resource for future formation of metropolitan quantum-secure communications networks.

Short-wave infrared (SWIR) emitters are at the center of ground-breaking applications in biomedical imaging, next-generation optoelectronic devices, and optical communications. Colloidal nanocrystals based on indium arsenide are some of the most promising SWIR emitters to date. However, the lack of single-particle spectroscopic methods accessible in the SWIR has prevented advances in both nanocrystal synthesis and fundamental characterization of emitters. Here, we demonstrate an implementation of a solution photon correlation Fourier spectroscopy (s-PCFS) experiment utilizing the SWIR sensitivity and time resolution of superconducting nanowire single-photon detectors to extract single-particle emission linewidths from colloidal indium arsenide/cadmium selenide (InAs/CdSe) core/shell nanocrystals emissive from 1.2 to 1.6 μm. We show that the average single InAs/CdSe nanocrystal fluorescence linewidth is, remarkably, as narrow as 52 meV, similar to what has been observed in some of the most narrowband nanostructured emitters in the visible region. Additionally, the single nanocrystal fluorescence linewidth increases with increasing shell thickness, suggesting exciton-phonon coupling as the dominant emission line-broadening mechanism in this system. The development of the SWIR s-PCFS technique has enabled measurements of spectral linewidths of colloidal SWIR-emissive NCs in solution and provides a platform to study the single NC spectral characteristics of SWIR emitters.

We demonstrate the generation of high-dimensional time-frequency entangled photon pair states and the preservation of entanglement after transmission across a 42-km telecom fiber by violating a high-dimensional Einstein-Podolsky-Rosen steering inequality.

We implemented an active feedback loop to compensate path-length drift on a deployed ~84-km-long optical fiber link between Lincoln Laboratory and MIT to enable quantum networking measurements and applications.

We implemented an active feedback scheme to stabilize an ∼84 km deployed optical fiber between Lincoln Laboratory and MIT Campus. The residual fluctuations of less than 193 attoseconds RMS enable quantum networking and quantum secure communications.

We investigated the phase noise of an ~83-km-long optical fiber link between Lincoln Laboratory and MIT for a quantum communication system and observed a noise process that is not governed entirely by a random-walk process.