Quantum computing (QC) is theorized to solve certain important problems much faster than classical computers. The current state of QC, the noisy intermediate-scale quantum (NISQ) era, is limited in the scope of problems it can solve, largely due to the quantity of reliable qubits available to universal quantum operations. And while all available quantum computing systems have their advantages, ion-based systems have been shown to be a reliable option with low infidelity and a capability for universal gating procedure. These advantages are dependent on achieving low crosstalk when addressing ions, a vital challenge for this QC system, particularly when using only bulk optic systems. Here we show a microfabricated planar waveguide which can selectively interact in free space with 8 trapped Ba+ ions. This performance meets or exceeds that of similar waveguides couple to trapped ion systems and shows a reliable method to selectively interact with ions bound by a Paul Trap using imaged waveguide outputs.
We report a fully-packaged, on-chip multi-photon-pair source using spontaneous-four-wave-mixing (SFWM) in silicon waveguide spirals. Our source consists of four, two-centimeter long spiral waveguides that are pumped in parallel using a pulsed laser source. We detected a four-fold coincidence rate of 180±20Hz, corresponding to an on-chip coincidence rate of 908±42Hz.
The star coupler is an integrated diffractive element which realizes an imperfect discrete Fourier transform in the optical path basis. We simulate star couplers of many different sizes / dimensions and calculate their mixing entropy and their transmission. Based on these results, we discuss the suitability of star coupler devices for enabling multi-plane light conversion in the path basis using photonic integrated circuits.
We lay down a general scheme to quantify the amount of genuine tripartite entanglement present in the spatial and energy-time degrees of freedom using the correlations naturally present in many such sources. To that end, we test our method using the three-photon states generated in three-party extensions of spontaneous parametric down-conversion, and demonstrate that a substantial amount of spatial and energy-time genuine tripartite entanglement can exist for reasonable experimental sources.
Silicon photonic foundries offer one path for scaling quantum photonic integrated circuits to useful sizes composed of many circuit elements. I will describe our group’s work using the AIM Photonics Foundry to create sources of high-dimensional entanglement across many waveguide paths by exciting arrays of microring-resonator photon pair sources in parallel. Aspects of our work include efficient schemes to certify and quantify entanglement, multi-mode components for manipulating high-dimensional states of light, and advanced packaging techniques.
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.
This Conference Presentation, “Efficiently quantifying entanglement in high-dimensional quantum photonic systems,” was recorded for the Photonics West 2021 Digital Forum.
Silicon-based photonics is mobilizing into a manufacturing industry with specialized integrated circuit design requirements for applications in low power cloud computing, high speed wireless, smart sensing, and augmented imaging. The AIM Photonics Manufacturing USA Institute, which operates the world’s most advanced 300mm semiconductor research fab, has co-developed a Process Design Kit (PDK) in fabless circuit design for these expanding digital and analog applications; however, there currently isn’t available an in-depth curriculum to train engineers (academia, industry) in the AIM PDK process and Electronic Photonic Design Automation (EPDA) software. AIM Photonics Academy, an education initiative of AIM Photonics based at MIT, has collaborated with faculty to create three online MOOC edX courses that (1) introduce integrated photonics devices, and applications performance needs and metrics; and (2) train into the AIM PDK and specialized EPDA tools in a six week design project to lay out an application-specific photonic transceiver. The courses are structured around asynchronous video lectures and exploratory design problems that involve Python and Matlab-based first-principles calculations (systems modeling) or advanced EPDA tools (circuit design and layout). The online MOOC courses can optionally form a tandem blended learning component with two AIM Photonics Academy on-site training programs: the annual AIM Summer Academy one-week intensive program (held every July at MIT), or a photonic integrated circuit testing workshop (the first workshop is planned for fall 2019). These courses are a cornerstone effort at AIM to found and support a specialized cohort community of future integrated photonics designers.
A modular laboratory curriculum with exercises for students and lesson plans for teachers is presented. Fundamentals of basic integrated photonic (IP) devices can be taught, first as a lecture-in-the-lab followed by “hands-on” laboratory measurements. This comprehensive curriculum utilizes data collected from the “AIM Photonics Institute PIC education chip” that was designed specifically for the purpose of education, and was fabricated at AIM SUNY Poly. Training using this modular curriculum will be performed through the AIM Photonics Academy network in New York (NY) and Massachusetts (MA), either as a full semester course or as a condensed boot-camp. A synergistic development and delivery of this curriculum will coherently leverage multiple resources across the network and can serve as a model for education and workforce development in other Manufacturing USA institutes, as well as for overseas partners.
Unitary operations using linear optics have many applications within the quantum and neuromorphic space. In silicon photonics, using networks of simple beam splitters and phase shifters have proven sufficient to realize large-scale arbitrary unitaries. While this technique has shown success with high fidelity, the grid physically scales with an upper bound of O(n2). Consequently, we propose to considerably reduce the footprint by using multimode interference (MMI) devices. In this paper, we investigate the active control of these MMIs and their suitability for approximating traditionally used unitary circuits.
As applications of quantum information and processing grow in scale in sophistication, the ability to quantify the resources present in very high-dimensional quantum systems is an important experimental problem needing solution. In particular, quantum entanglement is a resource fundamental to most applications in quantum information, but becomes intractable to measure in high dimensional systems, both because of the difficulty in obtaining a complete description of the entangled state, and the subsequent calculation of entanglement measures. In this paper, we discuss how one can measure record levels of entanglement simply using the same correlations employed to demonstrate the EPR paradox. To accomplish this, we developed a new entropic uncertainty relation where the Einstein-Podolsky-Rosen (EPR) correlations between positions and momenta of photon pairs bound quantum entropy, which in turn bounds entanglement. To sample the EPR correlations efficiently, one can sample at variable resolution, and combine this with relations in information theory so that only regions of high probability are sampled at high resolution, while entanglement is never over-estimated. This approach makes quantifying extremely high-dimensional entanglement scalable, with efficiency that actually improves with higher entanglement.
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. These spectrally indistinguishable photons can then be routed through optical waveguide circuitry, concatenated interferometers, to manipulate and entangle the photons into the desired quantum states. Photon sources and circuitry are only two of the three required pieces of the puzzle. The final piece which this research is aimed at interfacing with are trapped ion quantum memories, based on trapped Ytterbium ions. These 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 caveat with trapped ions is the interaction wavelength of the photons is 369.5nm and therefore the goal of this research is to develop entangled photon sources and circuitry in that wavelength regime to interact directly with the trapped ions and bypass the need for frequency conversion.
The need for bright efficient sources of entangled photons has been a subject of tremendous research over the last decade. Researchers have been working to increase the brightness and purity to help overcome the spontaneous nature of the sources. Periodic poling has been implemented to allow for the use of crystals that would not normally satisfy the phase matching conditions. Utilizing periodic poling and single mode waveguide confinement of the pump field has yielded extremely large effective nonlinearities in sources easily producing millions of photon pairs. Here we will demonstrate these large nonlinearity effects in a periodically poled potassium titanyl phosphate (PPKTP) waveguide as well as characterizing the source purity.
Measurements on quantum systems are always constrained by uncertainty relations. For traditional, projective measurements, uncertainty relations correspond to resolution limitations; a detector's position resolution is increased at the cost of its momentum resolution and vice-versa. However, many experiments in quantum measurement are now exploring non- or partially-projective measurements. For these techniques, measurement disturbance need not manifest as a blurring in the complementary domain. Here, we describe a technique for complementary imaging | obtaining sharp position and momentum distributions of a transverse optical field with a single set of measurements. Our technique consists of random, partially-projective filtering in position followed by projective measurements in momentum. The partial-projections extract information about position at the cost of injecting a small amount of noise into the momentum distribution, which can still be directly imaged. The position distribution is recovered via compressive sensing.
Here, we discuss the development of a new inequality in information theory; a Fano inequality suitable for continuous variables. With this inequality, we show how one can demonstrate Einstein-Podolsky-Rosen (EPR) steering in the position-momentum statistics of entangled photon pairs from spontaneous parametric down-conversion (SPDC). More importantly, we show how with sufficiently strong position and momentum correlations, we can demonstrate continuous-variable EPR steering without having to assume the photo-detectors have access to the entire joint intensity distribution. Moreover, we demonstrate this experimentally with the position and momentum statistics of entangled photon pairs in SPDC.
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