An optical digital to analog converter (oDAC) that may include (a) multiple optical paths that are parallel to each other; (b) a combiner, (c) a splitter that is configured to receive an optical signal at a splitter input and split the optical signal between multiple splitter outputs to provide multiple path input signals to the multiple optical paths. The multiple optical paths are configured to optically process, in parallel, path input signals to provide path output signals. Each optical path is configured to apply an optical process that comprises applying optical modulation, by an optical gate of the optical path and under a control of an electrical modulator, to provide an optical signal having a value selected out of multiple constellation levels. The combiner is configured to add the multiple path output signals to provide an oDAC output signal having a value selected from values of a single quadrature constellation.

The disclosure describes various aspects of a system with scalable and programmable coherent waveform generators. A network and digital-to-analog conversion (DAC) cards used by the network are described where each DAC card has a clock divider/replicator device with an input SYNC pin, a digital logic component, and one or more DAC components, and each output of the DAC components is used to control optical beams for a separate qubit of a quantum information processing (QIP) system. The network also includes a first distribution network to provide a clock signal to the clock divider/replicator device in the DAC cards, and a second distribution network to provide a start signal to the DAC cards, where the start signal is used by the digital logic component in the DAC card to assert the input SYNC pin when the start signal is asserted unless it is masked by the digital logic component.

The disclosure describes various aspects of a system with scalable and programmable coherent waveform generators. A network and digital-to-analog conversion (DAC) cards used by the network are described where each DAC card has a clock divider/replicator device with an input SYNC pin, a digital logic component, and one or more DAC components, and each output of the DAC components is used to control optical beams for a separate qubit of a quantum information processing (QIP) system. The network also includes a first distribution network to provide a clock signal to the clock divider/replicator device in the DAC cards, and a second distribution network to provide a start signal to the DAC cards, where the start signal is used by the digital logic component in the DAC card to assert the input SYNC pin when the start signal is asserted unless it is masked by the digital logic component.

Methods and apparatus for tuning a photonics-based component. An opto-electrical detector is configured to output an electrical signal based on a measurement of light intensity of the photonics-based component, the light intensity being proportional to an amount of detuning of the photonics-based component. Analog-to-digital conversion (ADC) circuitry is configured to output a digital signal based on the electrical signal output from the opto-electrical detector. Feedback control circuitry is configured to tune the photonics-based component based, at least in part, on the digital signal output from the ADC circuitry.

Methods and apparatus for tuning a photonics-based component. An opto-electrical detector is configured to output an electrical signal based on a measurement of light intensity of the photonics-based component, the light intensity being proportional to an amount of detuning of the photonics-based component. Analog-to-digital conversion (ADC) circuitry is configured to output a digital signal based on the electrical signal output from the opto-electrical detector. Feedback control circuitry is configured to tune the photonics-based component based, at least in part, on the digital signal output from the ADC circuitry.

The output computing unit includes cascade-connected N number of Y coupling elements having two inputs and one output, and N number of optical intensity modulators. The N number of light intensity modulators individually modulate the intensity of a continuous light to a second optical input port, which is different from a first optical input port to which no light is input or to which a signal light from an optical output port of a Y coupling element in a previous stage, out of two optical input ports of each of the cascade-connected N number of Y coupling elements, in accordance with corresponding bits of an N-bit electric digital signal. The output light acquired from the Y coupling element 1-N in the final stage is regarded as the N-bit digital analog computing result.

The output computing unit includes cascade-connected N number of Y coupling elements having two inputs and one output, and N number of optical intensity modulators. The N number of light intensity modulators individually modulate the intensity of a continuous light to a second optical input port, which is different from a first optical input port to which no light is input or to which a signal light from an optical output port of a Y coupling element in a previous stage, out of two optical input ports of each of the cascade-connected N number of Y coupling elements, in accordance with corresponding bits of an N-bit electric digital signal. The output light acquired from the Y coupling element 1-N in the final stage is regarded as the N-bit digital analog computing result.

A system for analog-to-digital conversion, preferably including one or more optical inputs, optical sources, phase remodulators, and/or photonic circuits, and optionally including detector banks and/or digital electronics. A method for analog-to-digital conversion, preferably including receiving an optical input signal, generating a phase-modulated optical signal, and/or generating a plurality of optical outputs, and optionally including generating a plurality of electrical outputs and/or encoding a digital representation of the outputs.

A photonic monobit analog-to-digital converter (ADC) includes an incoherent optical source, a dual optical modulator, a coupler, a coherent detector, a limiter, and a DSP. The incoherent optical source generates an optical noise signal. The dual optical modulator modulates phase and amplitude of an input complex baseband signal onto an input optical signal to generate an optical modulated signal. The coupler couples the modulated signal with the optical noise signal to generate a dithered optical signal. The coherent detector coherently detects a dithered in-phase (I) signal component and a dithered quadrature (Q) signal component associated with the input complex baseband signal using the dithered optical signal and a reference optical signal. The limiter outputs a complex decision signal based on the dithered I and Q signal components. The DSP generates a digital signal representative of the input complex baseband signal based on the complex decision signal.

A system for Nyquist zone disambiguation of a received broadband RF signal is disclosed. The system includes continuous-wave (CW) and pulsed photonic sources whose outputs may be combined into a single input. Both CW and pulsed components of the combined photonic input are modulated by sampling the received RF input signal. The system includes hybrid couplers for IQ demodulation of the modulated combined photonic signal. The system demultiplexes the demodulated inphase and quadrature differential photonic signals into their CW and pulsed component signals. The pulsed component signals may be digitized by narrowband multibit analog-digital converters (ADC) while the CW component signals are digitized by high speed low latency mono-bit ADCs to determine frequency components (e.g., bandwidth information) and other spectrum information of the RF input signal.