An optical logic device includes a distributed feedback laser configured to generate a first signal corresponding to distributed feedback laser output signal, the first signal being at a first wavelength. The device further includes a bandpass filter having a center frequency corresponding to the first wavelength. Additionally, the device can include an optical circulator having a first port coupled to a logic device input signal, a second port coupled to the first signal, and a third port coupled to the bandpass filter, wherein when the logic device input signal has a power above a predetermined threshold and there is a wavelength difference between the first wavelength and an input wavelength of the logic device input signal, a suppression of the first signal occurs.

An optical logic device includes a distributed feedback laser configured to generate a first signal corresponding to distributed feedback laser output signal, the first signal being at a first wavelength. The device further includes a bandpass filter having a center frequency corresponding to the first wavelength. Additionally, the device can include an optical circulator having a first port coupled to a logic device input signal, a second port coupled to the first signal, and a third port coupled to the bandpass filter, wherein when the logic device input signal has a power above a predetermined threshold and there is a wavelength difference between the first wavelength and an input wavelength of the logic device input signal, a suppression of the first signal occurs.

A two-photon logic gate introduces a phase shift between two photons using a Q-switched cavity with some nonlinearity. The two-photon logic gate catches photons in and releases photons from de-coupled cavity modes in response to electronic or photonic control signals. This catch-and-release two-photon gate can be formed in semiconductor photonic integrated circuit (PIC) that operates at room temperature. When combined with sources, linear circuits, other logic gates, and detectors, it can be used to make a quantum computer with up to 1000 error-corrected logical qubits on a cm.sup.2 PIC, with full qubit connectivity to avoid overhead. Two-qubit gate fidelity exceeding 99% is possible with near-term technology, and scaling beyond 99.9% is possible. Two-photon logic gates are also suitable for gate-based quantum digital computing and for analog quantum computing schemes, such as adiabatic quantum computing or quantum annealing.

A two-photon logic gate introduces a phase shift between two photons using a Q-switched cavity with some nonlinearity. The two-photon logic gate catches photons in and releases photons from de-coupled cavity modes in response to electronic or photonic control signals. This catch-and-release two-photon gate can be formed in semiconductor photonic integrated circuit (PIC) that operates at room temperature. When combined with sources, linear circuits, other logic gates, and detectors, it can be used to make a quantum computer with up to 1000 error-corrected logical qubits on a cm.sup.2 PIC, with full qubit connectivity to avoid overhead. Two-qubit gate fidelity exceeding 99% is possible with near-term technology, and scaling beyond 99.9% is possible. Two-photon logic gates are also suitable for gate-based quantum digital computing and for analog quantum computing schemes, such as adiabatic quantum computing or quantum annealing.

A method of performing a multiplication operation in the optical domain using a device (100) comprising: an optical waveguide (101), and a modulating element (102) that is optically coupled to the optical waveguide (101), the modulating element (102) modifying a transmission, reflection or absorption characteristic of the waveguide (101) dependant on its state, wherein the state of the modulating element (102) is adjustable by a write signal (103). The method comprises: encoding a first value to the write signal (103), using the write signal (103) to map the first value to a state of the modulating element (102); encoding a second value to a read signal (104); producing an output signal intensity as the transmitted or reflected read signal, wherein the product of the first value and the second value is encoded in the output signal intensity.

An optical-fiber atomic light-filtering apparatus comprising an optical-fiber coupling focusing collimating mirror, a first polarizing optical fiber, a first permanent magnetic ring, a pure iron frame shaped like the Chinese character , a heat preservation box, a first capillary atomic cell, an armored twisted-pair heating wire, a second permanent magnetic ring, a second polarizing optical fiber, a thermostat, a cable, a third permanent magnetic ring, a temperature sensor, a second capillary atomic cell, a fourth permanent magnetic ring, a third polarizing optical fiber and a photoelectric detector. The two pairs of permanent magnetic rings are matched with the pure iron frame shaped like the Chinese character to provide magnetic fields for the two capillary atomic cells working in the same temperature environment; a polarizing plane changes after interaction between a weak signal light and atoms.

An optical-fiber atomic light-filtering apparatus comprising an optical-fiber coupling focusing collimating mirror, a first polarizing optical fiber, a first permanent magnetic ring, a pure iron frame shaped like the Chinese character , a heat preservation box, a first capillary atomic cell, an armored twisted-pair heating wire, a second permanent magnetic ring, a second polarizing optical fiber, a thermostat, a cable, a third permanent magnetic ring, a temperature sensor, a second capillary atomic cell, a fourth permanent magnetic ring, a third polarizing optical fiber and a photoelectric detector. The two pairs of permanent magnetic rings are matched with the pure iron frame shaped like the Chinese character to provide magnetic fields for the two capillary atomic cells working in the same temperature environment; a polarizing plane changes after interaction between a weak signal light and atoms.

A method of generating a photon with multiple dimensions includes a step of generating a first photon encoded with quantum information in each of two or more frequency bins and at least one time bin. The method further includes performing a frequency dependent time operation to entangle (i.e. make non-separable) the frequency bins and the time bins in the photon.

A method of generating a photon with multiple dimensions includes a step of generating a first photon encoded with quantum information in each of two or more frequency bins and at least one time bin. The method further includes performing a frequency dependent time operation to entangle (i.e. make non-separable) the frequency bins and the time bins in the photon.

Provided is an optical transmission module which can generate PAM4 optical modulation signals without converting a plurality of binary electric signals to a multi-level electric signal. An optical transmission module (200) comprising: a light source (60) for emitting continuous waveform (CW) light; optical modulators (51,52,53) arranged in series with a path of the CW light configured to modulate the CW light by switching relatively large absorption and relatively small absorption of the optical modulators in response to a modulation signal applied to the respective optical modulators; and an arithmetic logic circuit (100) configured to receive a plurality of binary electrical signals, and then to perform logic operation on the plurality of binary electrical signals for generating a new plurality of binary electrical signals, wherein each of the new plurality of binary electrical signals is applied to the respective optical modulators as the modulation signal.