This PDF file contains the front matter associated with SPIE Proceedings Volume 11917.

With the recent passage of the National Quantum Initiative (NQI) into law, increased levels of Quantum research and workforce development will be enabled. Undoubtedly, this work will accelerate breakthroughs in many Quantum Information Science and Technology areas. In this talk, I will briefly describe the National Photonics Initiative (NPI) and it’s linkage to the National Quantum Initiative. Further, I will describe the background of the NQI and discuss the roles, as defined in the legislation, for the Office of Science and Technology Policy (OSTP), NIST, NSF and the DOE. Finally, I will describe the next steps planned to address funding “appropriation” process associated with the $1.275B that has been allocated to the work described in the legislation.

AIM Photonics seeks to advance integrated photonic circuit manufacturing technology development while simultaneously providing access to state-of-the-art fabrication, packaging, and testing capabilities for small-to-medium enterprises, academia, and the government; create an adaptive integrated photonic circuit workforce capable of meeting industry needs and thus further increasing domestic competitiveness; and meet participating commercial, defense, and civilian agency needs in this burgeoning technology area. The talk describes the status of AIM technology, current applications and potential development for photonic quantum systems.

In this talk, I describe new results on three research topics within my research group. We first describe some of the unusual optical properties of materials, known as epsilon-near-zero (ENZ) materials, for which the dielectric permittivity is very small. We describe some of the unusual geometrical optical properties of such materials and present theoretical predictions of how fundamental radiative properties are modified under such conditions. We also describe how these materials can display extremely large nonlinear optical effects under ENZ conditions [1,2]. The second topic of study is the filamentation of intense laser beams as they propagate through nonlinear optical materials. Our recent work has demonstrated that the threshold for filamentation can be raised by properly controlling the polarization properties of the transverse structure of the beam [3]. The third topic is quantum radiometry. Historically, black body radiation has been taken to constitute a calibration standard for optical instruments. However, the zero-point fluctuations of the electromagnetic field constitute another fundamental calibration standard. We have devised a means for calibrating the response of a spectrophotometer by utilizing these vacuum fluctuations to seed the process of spontaneous parametric down conversion [4].

Quantum frequency conversion between superconducting (SC) microwave qubits and telecom optical photons is critical for long distance communication of networked SC quantum processors. While SC qubits operate at cryogenic temperatures to sustain their quantum coherence, converting them to the optical domain enables transferring the quantum states to room temperature and over long distances. For such a quantum state transduction process, several schemes have been investigated, including optomechanics, magnons, piezomechanics, and Pockels electro-optics (EO). The EO conversion approach is particularly attractive since it is broadband, low noise, mechanically and thermally stable (i.e., does not rely on freestanding structures), scalable (largescale integration of EO devices with superconducting circuits is possible), and tunable (e.g., using bias voltages). In this presentation we review our progress in an electro-optic based quantum transduction and discuss the promises and challenges.

It would be difficult to overestimate the level of attention being paid worldwide to quantum information processing, and anticipated advantages it may offer to a wide variety of pursuits in engineering, technology, and basic science. Futurists muse on the wondrous possibilities and theorists formulate actual algorithms for advanced computing not possible with classical computing machines, if only there were scalable quantum computers. Further, several groups have performed compelling experiments related to quantum teleportation and quantum key distribution – both essential pieces for quantum cryptography. Still, it is a very challenging hardware problem to design architectures that support, appropriately protect, route, and process qubits to function as universal logic gates. To date, most of the optical successes toward this goal have been in bulk media, which is not easily scalable to carry out the required degree quantum error correction. In this talk, I will discuss a couple of the proposals that my collaborators at the Air Force Research Laboratory, at the Rochester Institute of Technology, and I have made toward addressing the issue, among others, of scalability. Further, thanks to the inception of the AIM Photonics Initiative, I will talk briefly about experimental tests that we have started and others that we have planned for assessing in situ the effectiveness of the devices that we have analyzed theoretically.

Most quantum experiments are based on repeated “trials”. We present a roadmap based on integrated photonics for “very fast” sources and detectors to achieve a large improvement in the speed at which such trials can be performed.

Trapped ions are among the top candidates for realizing high fidelity gate operations for quantum computation as well as other applications including quantum simulation and sensing [1]. However, scaling these systems up to the number of qubits required to solve interesting problems with conventional macroscopic traps quickly becomes intractable. To overcome the scalability challenge, advanced microfabrication techniques have been developed to support a variety of complex electrode layouts, allowing for precise and dynamic control of confining potentials. Using Sandia’s microfabricated surface ion traps, which feature low heating rates, high trap frequencies, and long trapping times, we demonstrate novel classical control techniques that employ parametric voltage solutions for elegant composition of shuttling operations and accurate control over the curvature of the confining potential. To demonstrate the viability of Sandia's microfabricated ion traps for quantum information processing, we’ve realized of high-fidelity single-qubit gates below a rigorous fault tolerance threshold for general noise [2,3] and two-qubit Mølmer-Sørensen gates with a process fidelity of 99.58(6)%.

Integrated Photonic circuits provide a scalable and stable platform for realizing quantum information technologies. In this talk I will discuss integrated photonic chips for the production, manipulation and storage of quantum bits (qubits). I will present two platforms for quantum photonics: one based on Silicon which leverages the high density of Silicon Photonic technologies, and the other based on Aluminum Nitride (AlN) which operates at visible/UV wavelengths and is highly suited for the realization of hybrid quantum systems based on atoms and solid state emitters. Lastly, I will present our related work on integrated photonic packaging at AIM Photonics Test, Assembling and Packaging (TAP) facility. The packaging capabilities include die, laser and fiber attach – all of which enable the realization of complex quantum photonic circuits.

In this talk we will review the latest developments in Ytterbium based fiber laser and OPO technologies and discuss their implementation in a range of quantum based experiments. This will include a route to the detection of quantum signatures at 690nm (using third harmonic generation); the generation and detection of down-converted photon pairs at 2.080 μm (as a potential source for free-space quantum communications) and; the use of our tuneable near-IR OPO source to interrogate SiN and AlN integrated waveguides with entangled photons.

Career and Workforce Panel presentation

The precise quantum control of single photons, together with the intrinsic advantage of being mobile make optical quantum system ideally suited for delegated quantum information tasks, reaching from well-established quantum cryptography to quantum clouds and quantum computer networks. Here I present that the exploit of quantum photonics allows for a variety of quantum-enhanced data security for quantum and classical computers. The latter is based on feasible hybrid classical-quantum technology, which shows promising new applications of readily available quantum photonics technology for complex data processing. As outlook I will discuss technological challenges for the scale up of photonic quantum computers, and our group’s current work for addressing some of those.

Photons play a central role in many areas of quantum information science, either as qubit themselves or to mediate interactions between long-lived matter based qubits. Techniques for (1) high-fidelity generation, (2) precise manipulation and (3) ultra-efficient detection of quantum states of light are therefore a prerequisite for virtually all quantum technologies. A quantum photonics processor is the union of these three core technologies into a single system, and, bolstered by advances in integrated photonics, promises to be a versatile platform for quantum information science. In this talk we present recent progress towards large-scale quantum photonic processors, leveraging the platform of silicon photonics. We demonstrate how quantum photonic processors can accelerate both quantum and classical machine learning, and how optimization techniques can enhance large-scale quantum control.

Integrated micro- and nano-structures allows for the efficient generation of photon pairs via parametric fluorescence, thanks to the enhancement of the light-matter interaction associated with light confinement in small volumes. For instance, the efficiency of spontaneous four wave mixing in a silicon micro ring resonator can range up to 10 orders of magnitude larger than in bulk silicon. Yet the advantages of using integrated devices go well beyond the sole efficiency improvement, for micro structures grant an unprecedented control over the properties of generated non-classical light. For instance, in a single photonic integrated circuit, one can exploit the interferences of many optical elements to construct complex multipartite states in a compact, stable, and scalable system. In this talk I will focus on the generation of photon pairs and show how their spectral properties can be engineered in an integrated device for use as building blocks in the construction of a whole variety of states, from heralded single-photons to multipartite states.

Hybrid quantum interconnects and processor components are likely to play an important role in future scalable quantum communication and computation networks. In this talk, I will outline several nascent ideas for a new type of hybrid system, composed of mechanical elements, superconducting metamaterials, and superconducting qubits, which could be applicable to quantum transduction and memory functions. Before introducing these new ideas, I will start with a summary of recent incipient work at Syracuse that has inspired them. My summary will include a brief overview of efforts in the LaHaye group to investigate interactions between a superconducting transmon qubit and UHF nanomechanical element1; as well, I will highlight work conducted concomitantly and independently by the Plourde group to study the mode structure2 and cQED interactions of a superconducting metamaterial transmission line. The talk will then conclude with an overview of related ideas to utilize qubit-coupled nanoresonator architectures as platforms for quantum simulation.

Photonics is at the forefront of quantum computing and simulations. It enabled a host of pioneering demonstrations of the variational quantum eigensolver (VQE) algorithm, of molecular vibronic spectra and dynamics simulations, and of experimental Hamiltonian learning. It offers a versatile platform to process quantum information with low noise in a multitude of encodings, ranging from spatial or polarization degrees of freedom, to temporal modes. We discuss how frequency encoding, where qubits are represented by photons in narrow frequency bins, can be utilized for simulating complex many-body quantum phenomena in nuclear physics and quantum field theory. Using an all-optical quantum frequency processor, the ground-state energies of light nuclei including the triton, 3He, and the alpha particle are computed. Complementing these calculations and utilizing a 68-dimensional Hilbert space, our photonic simulator is used to perform sub-nucleon calculations of the two-body and three-body forces between heavy mesons in the Schwinger model. This work is a first step in simulating subatomic many-body physics on quantum frequency processors---augmenting classical computations that bridge scales from quarks to nuclei.

We show that using the electric field as a quantization variable in nonlinear optics leads to incorrect expressions for the squeezing parameters in SPDC, the conversion rates in frequency conversion, and the wrong behavior of cross- and self-phase modulation. This observation is related to the fact that if the electric field is written as a linear combination of boson creation and annihilation operators one cannot satisfy Maxwell’s equations in a nonlinear dielectric.

Solid-state materials are providing new insights into quantum optics and offer unique opportunities for quantum information science. In this talk I will discuss how localized quantum emitters in solid-state materials can be leveraged to support the generation of quantum states of light as well as how these same objects can enable new approaches to metrology.

We will discuss our recent efforts in engineering various integrated photonics devices and platforms for manipulating the fundamental quantum properties of photons.

Although existing experiments have implemented protocols employing up to 10 or even 12 photons, the inefficiencies of sources has resulted in exceedingly low rates of these high-photon events. Single and entangled-photon emitters both suffer from probabilistic operation, substantial losses, or both, so that extrapolating even to 20 photons is discouraging. However, recent experiments employing multiplexing techniques can trade overall rate (or component count) for increased probability, e.g., factors of 10-30 enhancement have been demonstrated. How far can such experiments be pushed? Using our best guesstimates on what system capabilities may be feasible, we discuss the near-term future for multi-photon quantum processing.

Measured quantum systems exhibit their own form of dynamics that is stochastic and nonunitary. Of particular interest are the most likely paths in quantum space between two boundary conditions in a certain time. I will show how caustic structures can arise in these paths, and predict the occurrence of chaos. In the former case, comparison with experiments on superconducting quantum circuits will be given.

Quantum information processing relies on the fundamental property of quantum interference, where the quality of the interference directly correlates to the indistinguishability of the interacting particles. The creation of these indistinguishable particles, photons in this case, has conventionally been accomplished with nonlinear crystals and optical filters to remove spectral distinguishability, albeit sacrificing the number of photons. This research describes the use of an integrated aluminum nitride microring resonator circuit to selectively generate photon pairs at the narrow cavity transmissions, thereby producing spectrally indistinguishable photons in the ultraviolet regime to interact with trapped ion quantum memories. The spectral characteristics of these photons must be carefully controlled for two reasons: (i) interference quality depends on the spectral indistinguishability, and (ii) the wavelength must be strictly controlled to interact with atomic transitions. The specific ion of interest for these trapped ion quantum memories is Ytterbium which has a transition at 369.5 nm with 12.5 GHz offset levels. Ytterbium ions serve as very long lived and stable quantum memories with storage times on the order of 10’s of minutes, compared with photonic quantum memories which are limited to 10-6 to 10-3 seconds. The combination of the long-lived atomic memory, integrated photonic circuitry, and the photonic quantum bits are necessary to produce the first quantum information processors. In this seminar, I will present results on ultraviolet wavelength operation, dispersion analysis, propagation loss in aluminum nitride waveguides, and the path forward to towards multiwavelength integration.

Integrated photonics panel presentation

The precision of an atomic clock based on the standard Ramsey spectroscopy, involving the measurement of the population of the atomic excited state, essentially a measurement of energy, is determined by the free evolution time T between successive /2 pulses. The longer the time T, the narrower the Ramsey interference fringes and thus the greater the precision. The stability of an atomic clock is also increased with increased T. But there are practical limits to the degree to which T can be extended. The main approach so far has been through the introduction of the so-called atomic fountain clocks. In this talk we present alternative approach not based on extending T but based on collective atomic states where a non-classical observable, an observable having no classical counterpart, is to be measured. This is the collective atomic, or SU(2), parity for an ensemble of two-level atoms. We show that with this observable the corresponding Ramsey-like fringes can become remarkably narrower with an increasing number of atoms in the ensemble even when the atomics are not prepared in an entangled state. By preparing the atoms in an entangled state, such as a state known to be spin-squeezed, the precision can be further increased through atomic parity measurements. The issue of performing the required collective atomic parity measurements will be discussed.

Photonic integrated circuits (PICs) have become increasingly important in classical communications applications over the past decades, including as transmitters and receivers in long-haul, metro and datacenter interconnects. Many of the same attributes that make PICs attractive for these applications — compactness, high bandwidth, and the ability to control large numbers of optical modes with high phase stability — also make them appealing for quantum information processing. Here we review our recent progress in developing PICs for quantum information processing. The first part of the talk will describe architectures for programmable PIC that can be programmed to implement arbitrary unitary linear-optics transformations. We recently applied these chips to applications ranging from deep neural networks1 to quantum transport simulations2, but this talk will focus on recent advances in entangled photon sources3 and proposals for on-demand single photon sources4, photon-photon nonlinear interactions, and neural neural network processors5. The second part of the talk will consider new PIC platforms that can be integrated directly with atom-like quantum memories. In particular, we will discuss PICs based on the AlGaN-sapphire material system that are transparent in the UV-VIS spectrum, for applications in multiplexed quantum repeaters. This PIC platform now allows quality factors in excess of 20,000 for wavelengths as short as 369nm6 and the integration of diamond nitrogen vacancy color centers and superconducting single-photon resolving detectors7. Finally, we describe a blueprint for scalable cluster-state quantum computing that builds on large numbers of cavity-coupled diamond color centers networked by photonic switches and waveguides8.

Single-photon detector array technologies have advanced significantly in recent years. Cameras now exist that are not only sensitive to single photons but the individual pixels in the sensor provide photon time-of-arrival information the picosecond regime. Such unprecedented sensitivity and temporal resolution opens up a number of exiting new applications, such as light-in-flight imaging, looking around corners with laser echoes, and seeing through dense scattering media. I will discuss the recent developments of the camera technology and discuss our latest results. I will give details of our latest field trials, where we have been using single-photon detector array sensors to see through fog and smoke, discuss the application to ultra-fast imaging in three dimensions, and give details of quantum imaging of high-dimensional entanglement.

At the core of most quantum technologies, including quantum networks and quantum simulators, is the development of homogeneous, long lived qubits with excellent optical interfaces, and the development of high efficiency and robust optical interconnects for such qubits. To achieve this goal, we have been studying color centers in diamond (SiV, SnV) and silicon carbide (VSi in 4H SiC), in combination with novel fabrication techniques, and relying on the powerful and fast photonics inverse design approach that we have developed. Our inverse design approach offers a powerful tool to implement classical and quantum photonic circuits with superior properties, including robustness to errors in fabrication and temperature, compact footprints, novel functionalities, and high efficiencies. We illustrate this with a number of demonstrated devices, including efficient quantum emitter-photon interfaces for color centers in diamond and in silicon carbide. We are also employing this approach to implement a quantum simulator based on color centers in semiconductors.

Efficient single-photon detectors have enabled new directions in experimental physics. Superconducting nanowire single-photon detectors (SNSPDs) are a vital component in loophole-free Bell inequality violation, metrology beyond the shot-noise limit, and nuclear clock transition sensing. We discuss recent progress in cryogenic silicon photonic platforms at the National Institute of Standards and Technology (NIST). These platforms co-integrate SNSPDs, silicon-on-insulator waveguides, superconducting amplifiers, and all-silicon light sources based on emissive crystal defect centers. Together, these elements lay a foundation for large-scale quantum information systems and extremely low-power neuromorphic architectures. Neuromorphic photonics uses the complementary properties of optics and electronics to realize information processing capabilities far beyond what is possible with pure electronics. Its performance potentials are highly desired as neural network approaches have retaken the helm of machine learning. We present recent results in neuromorphic photonic architectures at NIST and Princeton: one signaling at single-photon levels, one signaling on sub-nanosecond timescales, both propelled by the emerging industrialization of silicon photonics. Neuromorphic and quantum processing approaches based on silicon photonics will overlap substantially in terms of technical challenges and enabling technologies.

Ongoing research at SUNY Polytechnic Institute to enable large scale fabrication of quantum devices with tightly controlled performance characteristics will be presented. Josephson junctions and transmon qubits patterned with 193 nm lithography will be used to illustrate how advanced process tools can control critical dimensions of devices, necessary for building larger ensembles of qubits. Advances in the CMOS industry enable superior surface roughness and interface quality to be achieved across the entire 300mm wafer – some examples will be presented. The integration of photonic circuits (waveguides and on-chip cryogenic IR emitters) with superconducting Josephson junctions to enable large-scale neuromorphic computing structures in the near future will be discussed. Ongoing work on developing materials and processes for UV-transparent photonic circuits at 300mm will be presented – such chips could be useful as part of the interface to trapped ion qubits. The talk will wrap up with a discussion of the synergies in technology development, and functionality integration that can be achieved using an advanced fabrication facility.

Superconducting qubits based on Josephson junctions are one of the leading candidates for building a largescale quantum information processor. There have been significant advances in the performance of superconducting qubits over the past decade and there is currently rapid progress in the development of systems with up to tens of qubits. In order to build to yet larger systems, new techniques will need to be developed to address the overhead requirements for room-temperature electronics hardware and cryostat wiring for controlling and reading out large numbers of qubits. One approach to this challenge involves implementing more of the qubit control and readout in the low-temperature environment. I will describe our efforts on integrating superconducting classical digital circuitry with superconducting qubits for coherent control and readout.

Entanglement and encoding in discrete frequency bins – essentially a quantum analogue of wavelength-division multiplexing – represents a relatively new degree of freedom for quantum information with photons. In this talk I discuss biphoton frequency combs, generated either by spontaneous four-wave mixing (SFWM) from on-chip microring resonators or by spectral filtering of spontaneous parametric down conversion (SPDC) in second order nonlinear crystals. Potential advantages include generation of high dimensional units of quantum information (qudits), which can carry multiple qubits per photon, robust transmission over fiber, frequency parallelism and routing, and compatibility with on-chip implementations, as well as hyperentanglement with other photonic degrees, e.g., time-frequency hyperentanglement. Since the initial experiments less than two years ago, frequency bin quantum photonics has been advancing rapidly [1-8]. In this talk I will discuss a method using pulse shapers and phase modulators in order to mix different frequencies and perform two photon interference experiments for characterization of the frequency-bin entanglement. Similar components (pulse shapers and phase modulators) may be used to manipulate the frequency-encoded quantum states; this will be described in another talk by our collaborators at Oak Ridge National Labs. I will also discuss the use of time bins and frequency bins as independent degrees of freedom in a quantum encoding fashion to realize what we believe to be the first deterministic two qudit gates. Finally, I comment briefly on potential applications and on prospects for realization of integrated frequency bin quantum photonics.

Real-world platforms for enabling quantum information technologies are varied and imperfect; therefore, the quantum resources they provide must be characterized before they can be used. For some tasks, such as secure communication, resources like entanglement must be guaranteed, or certified. In large quantum systems, traditional approaches demand an intractable number of measurements. We demonstrate a practical method for quantifying high-dimensional entanglement from extremely limited data that does not require numerical optimization techniques. Using only 6,456 measurements, we certify over 7 ebits of entanglement-of-formation shared by entangled photon pairs in a joint-measurement space exceeding 68 billion dimensions.

Photons offer a myriad of bases for encoding quantum information, including such popular choices as polarization, spatial modes, and time bins. And due to frequency’s inherent stability and compatibility with optical fiber, spectral modes provide a particularly attractive Hilbert space for quantum computation. Yet control and processing of such modes can prove quite challenging, typically requiring complicated operations and strong classical pump fields. In this talk, I will describe our paradigm for universal quantum computation based on frequency-bin qubits and standard lightwave technology: electro-optic phase modulators and Fourier-transform pulse shapers. Our approach offers excellent resource scaling, parallelizability, and compatibility with fiber-optic technology. I will discuss experiments so far, including frequency-bin Hadamard and tritter gates, both with ultrahigh fidelity and broad bandwidth; quantum interference and independent spectral control of two photons in the same optical fiber; and a frequency-bin controlled-NOT, the first of its kind. Such experiments are augmented by Bayesian machine learning techniques, allowing for more detailed gate analysis than possible with conventional approaches. Finally, I will conclude with an outlook on future work, highlighting opportunities to address current challenges and summarizing the potential for our technique, not only in quantum computation proper, but also quantum interconnects, frequency-multiplexed networks, and on-chip integration.

Photon pair sources are fundamental building blocks for quantum entanglement and quantum communication. Recent studies in silicon photonics have documented promising characteristics for photon pair sources within the telecommunications band, including sub-milliwatt optical pump power, high spectral brightness, and high photon purity. However, most quantum systems suitable for local operation (e.g., storage/computation) support optical transitions in the visible or short nearinfrared bands. In comparison to telecommunications wavelengths, the significantly higher optical attenuation in silica at such wavelengths limits the length scale over which optical-fiber-based quantum communication between such local nodes can take place. One approach to connect such systems over fiber is through a photon pair source that can bridge the visible and telecom bands, but an appropriate source, which should produce narrow-band photon pairs with a high signal-to-noise ratio, has not yet been developed in an integrated platform. Here, we demonstrate a nanophotonic visible-telecom photon pair source for the first time, using high quality factor silicon nitride resonators to generate narrow-band photon pairs with unprecedented purity and brightness, with coincidence-toaccidental ratio (CAR) up to 3,780 ± 140 and detected photon-pair flux up to (18,400 ± 1,000) pairs/s. We further demonstrate visible-telecom time-energy entanglement and its distribution over a 20 km fiber, far exceeding the fiber length over which purely visible wavelength quantum light sources can be transmitted. Finally, we show how dispersion engineering of the microresonators enables the connections of different species of trapped atoms/ions, defect centers, and quantum dots to the telecommunications bands for future quantum communication systems.