Abstract: Provided herein is a photonic integrated circuit and methods for controlling a photonic integrated circuit that can utilize the resonant frequency of one or more components of the photonic integrated circuit to enhance the response of the circuit. At least one component of the photonic integrated circuit can be driven by an electrical signal whose frequency is substantially equal to the mechanical resonance frequency of the component such that the response of the optical component is increased. The component of the photonic integrated circuit can include a phase shifter that can impart a phase shift on a received optical signal. By driving the phase shifter with an electrical signal that is equal to the mechanical resonance frequency of the optical phase shifter, less power can be required to impart a desired phase shift on a received optical signal. The optical components can be implemented using piezoelectric cantilevers.

Abstract: A spectrally multiplexed quantum repeater (SMuQR) based on spatially arrayed nodes of frequency-multiplexed multi-qubit registers uses the natural inhomogeneous distribution of optical transition frequencies in solid state defect centers. This distribution enables spectrally selective, individual addressing of large numbers of defect centers within an optical diffraction limited spot along a long cavity or waveguide. The spectral selection relies on frequency shifting an incident optical field at a rate as fast as once per defect center lifetime. The defect centers are resonant at visible frequencies and emit visible single photons which are down-converted to a wavelength compatible with long-distance transmission via conventional optical fiber. The down-converted photons are all at the same telecommunications wavelength, with the different spectral bins mapped to different temporal bins to preserve the multiplexing in the time domain, for distribution to other nodes in the quantum network.

Abstract: Quantum information processing involves entangling large numbers of qubits, which can be realized as defect centers in a solid-state host. The qubits can be implemented as individual unit cells, each with its own control electronics, that are arrayed in a cryostat. Free-space control and pump beams address the qubit unit cells through a cryostat window. The qubit unit cells emit light in response to these control and pump beams and microwave pulses applied by the control electronics. The emitted light propagates through free space to a mode mixer, which interferes the optical modes from adjacent qubit unit cells for heralded Bell measurements. The qubit unit cells are small (e.g., 10 ?m square), so they can be tiled in arrays of up to millions, addressed by free-space optics with micron-scale spot sizes. The processing overhead for this architecture remains relatively constant, even with large numbers of qubits, enabling scalable large-scale quantum information processing.

Abstract: Methods and systems are described for precisely adjusting characteristics of microfabricated devices after device fabrication. The adjustments can be carried out in parallel on a plurality of the microfabricated devices. By carrying out the adjustment process, uniformity of feature sizes to a few picometers (one standard deviation) and corresponding uniformity of operating characteristics for a plurality of microfabricated devices are possible.

Abstract: A spatial light modulator (SLM) comprised of a 2D array of optically-controlled semiconductor nanocavities can have a fast modulation rate, small pixel pitch, low pixel tuning energy, and millions of pixels. Incoherent pump light from a control projector tunes each PhC cavity via the free-carrier dispersion effect, thereby modulating the coherent probe field emitted from the cavity array. The use of high-Q/V semiconductor cavities enables energy-efficient all-optical control and eliminates the need for individual tuning elements, which degrade the performance and limit the size of the optical surface. Using this technique, an SLM with 106 pixels, micron-order pixel pitch, and GHz-order refresh rates could be realized with less than 1 W of pump power.

Abstract: Quantum information processing involves entangling large numbers of qubits, which can be realized as defect centers in a solid-state host. The qubits can be implemented as individual unit cells, each with its own control electronics, that are arrayed in a cryostat. Free-space control and pump beams address the qubit unit cells through a cryostat window. The qubit unit cells emit light in response to these control and pump beams and microwave pulses applied by the control electronics. The emitted light propagates through free space to a mode mixer, which interferes the optical modes from adjacent qubit unit cells for heralded Bell measurements. The qubit unit cells are small (e.g., 10 ?m square), so they can be tiled in arrays of up to millions, addressed by free-space optics with micron-scale spot sizes. The processing overhead for this architecture remains relatively constant, even with large numbers of qubits, enabling scalable large-scale quantum information processing.

Abstract: An all-photonic computational accelerator encodes information in the amplitudes of frequency modes stored in a ring resonator. Nonlinear optical processes enable interaction among these modes. Both the matrix multiplication and element-wise activation functions on these modes (the artificial neurons) occur through coherent processes, enabling the representation of negative and complex numbers without digital electronics. This accelerator has a lower hardware footprint than electronic and optical accelerators, as the matrix multiplication happens in a single multimode resonator on chip. Our architecture provides a unitary, reversible mode of computation, enabling on-chip analog Hamiltonian-echo backpropagation for gradient descent and other self-learning tasks. Moreover, the computational speed increases with the power of the pumps to arbitrarily high rates, as long as the circuitry can sustain the higher optical power.

Abstract: A spectrally multiplexed quantum repeater (SMuQR) based on spatially arrayed nodes of frequency-multiplexed multi-qubit registers uses the natural inhomogeneous distribution of optical transition frequencies in solid state defect centers. This distribution enables spectrally selective, individual addressing of large numbers of defect centers within an optical diffraction limited spot along a long cavity or waveguide. The spectral selection relies on frequency shifting an incident optical field at a rate as fast as once per defect center lifetime. The defect centers are resonant at visible frequencies and emit visible single photons which are down-converted to a wavelength compatible with long-distance transmission via conventional optical fiber. The down-converted photons are all at the same telecommunications wavelength, with the different spectral bins mapped to different temporal bins to preserve the multiplexing in the time domain, for distribution to other nodes in the quantum network.

Abstract: We disclose optical entanglement distribution in quantum networks based on a quasi-deterministic entangled photon pair source. Combining heralded photonic Bell pair generation with spectral mode conversion to interface with quantum memories eliminates switching losses due to multiplexing in the source. This zero-added-loss multiplexing (ZALM) Bell pair source is especially useful for the particularly challenging problem of long-baseline entanglement distribution via satellites and ground-based memories, where it unlocks additional advantages: (i) the substantially higher channel efficiency ? of downlinks versus uplinks with realistic adaptive optics, and (ii) photon loss occurring before interaction with the quantum memory—i.e., Alice and Bob receiving rather than transmitting—improve entanglement generation rate scaling by (?{square root over (?)}).

Abstract: Many of the features of neural networks for machine learning can naturally be mapped into the quantum optical domain by introducing the quantum optical neural network (QONN). A QONN can be performed to perform a range of quantum information processing tasks, including newly developed protocols for quantum optical state compression, reinforcement learning, black-box quantum simulation and one way quantum repeaters. A QONN can generalize from only a small set of training data onto previously unseen inputs. Simulations indicate that QONNs are a powerful design tool for quantum optical systems and, leveraging advances in integrated quantum photonics, a promising architecture for next generation quantum processors.

Abstract: An atom control architecture based on VIS-IR photonic integrated circuit (PIC) technology is characterized by (1) visible (VIS) and near-infrared (IR) wavelength operation, (2) channel counts extensible beyond 1000s of individually addressable atoms, (3) high intensity modulation extinction and (4) repeatability compatible with low gate errors, and (5) fast switching times. A 16-channel SiN-based APIC with (5.8±0.4) ns response times and <?30 dB extinction ratio at a wavelength of 780 nm. Based on a complementary metal-oxide-semiconductor (CMOS) fabrication process, this atom-control PIC (APIC) technology can be used for atomic, molecular, and optical physics and emerging applications, from quantum computers with cold atoms or ions to quantum networks with solid-state color centers. This APIC technology is especially suitable for scalable quantum information processing based on optically programmable atomic systems.

Abstract: A multiplicative analog frequency transform optical neural network (MAFT-ONN) encodes data in the frequency domain, achieves matrix-vector products in a single shot using photoelectric multiplication, and uses a single electro-optic modulator for the nonlinear activation of all neurons in each layer. Photoelectric multiplication between radio frequency (RF)-encoded optical frequency combs allows single-shot matrix-vector multiplication and nonlinear activation, leading to high throughput and ultra-low latency. This frequency-encoding scheme can be implemented with several neurons per hardware spatial mode and allows for an arbitrary number of layers to be cascaded in the analog domain. For example, a three-layer DNN can compute over four million fully analog operations and implement both a convolutional and fully connected layer.

Abstract: NetCast is an optical neural network architecture that circumvents constraints on deep neural network (DNN) inference at the edge. Many DNNs have weight matrices that are too large to run on edge processors, leading to limitations on DNN inference at the edge or bandwidth bottlenecks between the edge and server that hosts the DNN. With NetCast, a weight server stores the DNN weight matrix in local memory, modulates the weights onto different spectral channels of an optical carrier, and distributes the weights to one or more clients via optical links. Each client stores the activations, or layer inputs, for the DNN and computes the matrix-vector product of those activations with the weights from the weight server in the optical domain. This multiplication can be performed coherently by interfering the spectrally multiplexed weights with spectrally multiplexed activations or incoherently by modulating the weight signal from the weight server with the activations.

Abstract: A 1D diamond nanobeam can act as a coherent mechanical interface between spin defect centers in diamond and telecom optical modes. The nanobeam includes embedded mechanical and electric field concentrators with mechanical and optical mode volumes of Vmech/?p3 ˜10?5 and Vopt/?3 ˜10?3, respectively. With a Group IV vacancy in the concentrator, the nanobeam can operate at spin-mechanical coupling rates approaching 40 MHz with high acousto-optical couplings. This nanobeam, used in an entanglement heralding scheme, can provide high-fidelity Bell pairs between quantum repeaters. Using the mechanical interface as an intermediary between the optical and spin subsystems enables addressing the spin defect center with telecom optics, bypassing the native wavelength of the spin. As the spin is never optically excited or addressed, the device can operate at temperatures up to 40 K with no appreciable spectral diffusion, limited by thermal losses.

Abstract: A filter-based color imaging array that resolves N different colors detects only 1/Nth of the incoming light. In the thermal infrared wavelength range, filtering loss is exacerbated by the lower sensor detectivity at infrared wavelengths than at visible wavelengths. To avoid loss due to filtering, most spectral imagers use bulky optics, such as diffraction gratings or Fourier transform interferometers, to resolve different colors. Fortunately, it is possible to avoid filtering loss without bulky optics: detect light with interleaved arrays of sub-wavelength-spaced antennas tuned to different wavelengths. An optically sensitive element inside each antenna absorbs light at the antenna's resonant wavelength. Metallic slot antennas offer high efficiency, intrinsic unidirectionality, and lower cross-talk than dipole or bowtie antennas. Graphene serves at the optically active material inside each antenna because its 2D nature makes it easily adaptable to this imager architecture.

Abstract: Optical microcavity resonance measurements can have readout noise matching the fundamental limit set by thermal fluctuations in the cavity. Small-heat-capacity, wavelength-scale microcavities can be used as bolometers that bypass the limitations of other bolometer technologies. The microcavities can be implemented as photonic crystal cavities or micro-disks that are thermally coupled to strong mid-IR or LWIR absorbers, such as pyrolytic carbon columns. Each microcavity and the associated absorber(s) rest on hollow pillars that extend from a substrate and thermally isolate the cavity and the absorber(s) from the rest of the bolometer. This ensures that thermal transfer to the absorbers is predominantly from radiation as opposed to from conduction. As the absorbers absorb thermal radiation, they shift the resonance wavelength of the cavity.

Abstract: Using the Meissner effect in superconductors, demonstrated here is the capability to create an arbitrarily high magnetic flux density (also sometimes referred to as “flux squeezing”). This technique has immediate applications for numerous technologies. For example, it allows the generation of very large magnetic fields (e.g., exceeding 1 Tesla) for nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), the generation of controlled magnetic fields for advanced superconducting quantum computing devices, and/or the like. The magnetic field concentration/increased flux density approaches can be applied to both static magnetic fields (i.e., direct current (DC) magnetic fields) and time-varying magnetic fields (i.e., alternating current (AC) magnetic fields) up to microwave frequencies.

Abstract: A reflective spatial light modulator (SLM) made of an electro-optic material in a one-sided Fabry-Perot resonator can provide phase and/or amplitude modulation with fine spatial resolution at speeds over a Gigahertz. The light is confined laterally within the electro-optic material/resonator layer stack with microlenses, index perturbations, or by patterning the layer stack into a two-dimensional (2D) array of vertically oriented micropillars. Alternatively, a photonic crystal guided mode resonator can vertically and laterally confine the resonant mode. In phase-only modulation mode, each SLM pixel can produce a ? phase shift under a bias voltage below 10 V, while maintaining nearly constant reflection amplitude. This high-speed SLM can be used in a wide range of new applications, from fully tunable metasurfaces to optical computing accelerators, high-speed interconnects, true 2D phased array beam steering, beam forming, or quantum computing with cold atom arrays.

Abstract: Deep learning performance is limited by computing power, which is in turn limited by energy consumption. Optics can make neural networks faster and more efficient, but current schemes suffer from limited connectivity and the large footprint of low-loss nanophotonic devices. Our optical neural network architecture addresses these problems using homodyne detection and optical data fan-out. It is scalable to large networks without sacrificing speed or consuming too much energy. It can perform inference and training and work with both fully connected and convolutional neural-network layers. In our architecture, each neural network layer operates on inputs and weights encoded onto optical pulse amplitudes. A homodyne detector computes the vector product of the inputs and weights. The nonlinear activation function is performed electronically on the output of this linear homodyne detection step.

Abstract: An evaporatively cooled device and a system including the same. In some embodiments, the system includes an oligolayer conductive sheet; a superconductor; a tunneling barrier, between the oligolayer conductive sheet and the superconductor; and a bias circuit, configured to apply a bias voltage across the tunneling barrier, the bias voltage being less than a gap voltage of the superconductor and greater than one-half of the gap voltage of the superconductor.