Quantum repeater systems and apparatus for quantum communication. In one aspect, a system includes a quantum signal receiver configured to receive a quantum field signal; a quantum signal converter configured to: sample quantum analog signals from a quantum field signal received by the quantum signal receiver; encode sampled quantum analog signals as corresponding digital quantum information in one or more qudits, comprising applying a hybrid analog-digital encoding operation to each quantum analog signal and a qudit in an initial state; decode digital quantum information stored in the one or more qudits as a recovered quantum field signal, comprising applying a hybrid digital-analog decoding operation to each qudit and a quantum analog register in an initial state; a quantum memory comprising qudits and configured to store digital quantum information encoded by the quantum signal converter; and a quantum signal transmitter configured to transmit the recovered quantum field signal.

Quantum repeater systems and apparatus for quantum communication. In one aspect, a system includes a quantum signal receiver configured to receive a quantum field signal; a quantum signal converter configured to: sample quantum analog signals from a quantum field signal received by the quantum signal receiver; encode sampled quantum analog signals as corresponding digital quantum information in one or more qudits, comprising applying a hybrid analog-digital encoding operation to each quantum analog signal and a qudit in an initial state; decode digital quantum information stored in the one or more qudits as a recovered quantum field signal, comprising applying a hybrid digital-analog decoding operation to each qudit and a quantum analog register in an initial state; a quantum memory comprising qudits and configured to store digital quantum information encoded by the quantum signal converter; and a quantum signal transmitter configured to transmit the recovered quantum field signal.

A high-voltage power supply system including a high-voltage regulator, a function generator, and a triggering circuit. The high-voltage regulator includes a microcontroller, a digital-to-analog convertor in communication with the microcontroller, and a high-voltage DC-DC converter in communication with the digital-to-analog converter. The function generator includes a high-voltage inverter including one or more MOSFET switches. The high-voltage inverter is in communication with the microcontroller of the high-voltage regulator. The triggering circuit includes one or more high-voltage electromechanical switches.

A high-voltage power supply system including a high-voltage regulator, a function generator, and a triggering circuit. The high-voltage regulator includes a microcontroller, a digital-to-analog convertor in communication with the microcontroller, and a high-voltage DC-DC converter in communication with the digital-to-analog converter. The function generator includes a high-voltage inverter including one or more MOSFET switches. The high-voltage inverter is in communication with the microcontroller of the high-voltage regulator. The triggering circuit includes one or more high-voltage electromechanical switches.

Quantum circuit assemblies that employ active pulse shaping in order to be able to control states of a plurality of qubits with signal pulses propagated over a shared signal propagation channel are disclosed. An example quantum circuit assembly includes a quantum circuit component that includes a first qubit, associated with a first frequency to control the state of the first qubit, and a second qubit, associated with a second frequency to control the state of the second qubit. A shared transmission channel is coupled to the first and second qubits. The assembly further includes a signal pulse generation circuit, configured to generate a signal pulse to be propagated over the shared transmission channel to control the state of the first qubit, where the signal pulse has a center frequency at the first frequency, a bandwidth that includes the second frequency, and a notch at the second frequency.

Quantum circuit assemblies that employ active pulse shaping in order to be able to control states of a plurality of qubits with signal pulses propagated over a shared signal propagation channel are disclosed. An example quantum circuit assembly includes a quantum circuit component that includes a first qubit, associated with a first frequency to control the state of the first qubit, and a second qubit, associated with a second frequency to control the state of the second qubit. A shared transmission channel is coupled to the first and second qubits. The assembly further includes a signal pulse generation circuit, configured to generate a signal pulse to be propagated over the shared transmission channel to control the state of the first qubit, where the signal pulse has a center frequency at the first frequency, a bandwidth that includes the second frequency, and a notch at the second frequency.

A circuit may include a two-stage feedforward compensated operational transconductance integrated amplifier, and the two-stage feedforward compensated operational transconductance integrated amplifier may include an input terminal, an output terminal, a signal path between the input terminal and the output terminal, the signal path comprising a first signal path gain stage and a second signal path gain stage, and ripple rejection circuitry coupled between the input terminal and an intermediate node of the signal path located between the first signal path gain stage and the second signal path gain stage. The ripple rejection circuitry may include a first ripple rejection circuitry gain stage coupled at its input to the input terminal and coupled at its output to an input terminal of a chopper circuit, a notch filter coupled at its input to an output terminal of the chopper circuit, and a second ripple rejection circuitry gain stage coupled at its input to an output terminal of the notch filter and coupled at its output to the intermediate node.

A circuit may include a two-stage feedforward compensated operational transconductance integrated amplifier, and the two-stage feedforward compensated operational transconductance integrated amplifier may include an input terminal, an output terminal, a signal path between the input terminal and the output terminal, the signal path comprising a first signal path gain stage and a second signal path gain stage, and ripple rejection circuitry coupled between the input terminal and an intermediate node of the signal path located between the first signal path gain stage and the second signal path gain stage. The ripple rejection circuitry may include a first ripple rejection circuitry gain stage coupled at its input to the input terminal and coupled at its output to an input terminal of a chopper circuit, a notch filter coupled at its input to an output terminal of the chopper circuit, and a second ripple rejection circuitry gain stage coupled at its input to an output terminal of the notch filter and coupled at its output to the intermediate node.

An analog filter, comprising, a first-time encoding machine (TEM); and a first delay element.

An inductive current digital-to-analog converter (DAC) includes: a power supply input adapted to be coupled to a power supply; a load terminal adapted to be coupled to a load; an inductor between the power supply input and the load terminal; and inductor current control circuitry. The inductor current control circuitry has: a sense signal input configured to receive a sense signal representative of the inductor current; a control code input configured to receive a control code; a set of switches having respective control terminals; and a set of control circuit outputs coupled to the respective control terminals of the set of switches. The inductor current control circuitry is configured to adjust control signals provided to the set of control circuit outputs based on the sense signal and the control code.