There are provided optical quantum logic gate (OQLG) characterized by 2.sup.n*2.sup.n unitary matrix and method of operating thereof. OQLG comprises first optical structure comprising 2.sup.n optically-coupled cores with one-to-one correspondence to input binary values specified by the matrix and second optical structure optically connected to the first optical structure and comprising 2.sup.n amplifying channels corresponding to the 2.sup.n cores. The first optical structure is configured to receive photons in binary fundamental quantum states (FQSs) representing input binary values specified by the matrix and to inject the received photons in the 2.sup.n cores, use optical coupling between the cores to mix the injected photons, and output photons into the second optical structure, wherein outputted mixed photons correspond to output binary values specified by the matrix. The second optical structure is configured to amplify, in a controllable manner, photons in the amplifying channels with preserving the FQSs and relative quantities of photons with different FQSs.

There are provided optical quantum logic gate (OQLG) characterized by 2.sup.n*2.sup.n unitary matrix and method of operating thereof. OQLG comprises first optical structure comprising 2.sup.n optically-coupled cores with one-to-one correspondence to input binary values specified by the matrix and second optical structure optically connected to the first optical structure and comprising 2.sup.n amplifying channels corresponding to the 2.sup.n cores. The first optical structure is configured to receive photons in binary fundamental quantum states (FQSs) representing input binary values specified by the matrix and to inject the received photons in the 2.sup.n cores, use optical coupling between the cores to mix the injected photons, and output photons into the second optical structure, wherein outputted mixed photons correspond to output binary values specified by the matrix. The second optical structure is configured to amplify, in a controllable manner, photons in the amplifying channels with preserving the FQSs and relative quantities of photons with different FQSs.

A system includes a first photonic integrated circuit. The circuit includes a qubit encoder configured to receive a spatial-mode qubit and convert the spatial-mode qubit to a temporal-mode qubit and an optical interconnect configured to receive and transmit the temporal-mode qubit. The system further includes a second photonic integrated circuit, itself including a qubit decoder configured to receive the temporal-mode qubit and convert the temporal-mode qubit back into the spatial-mode qubit.

A system includes a first photonic integrated circuit. The circuit includes a qubit encoder configured to receive a spatial-mode qubit and convert the spatial-mode qubit to a temporal-mode qubit and an optical interconnect configured to receive and transmit the temporal-mode qubit. The system further includes a second photonic integrated circuit, itself including a qubit decoder configured to receive the temporal-mode qubit and convert the temporal-mode qubit back into the spatial-mode qubit.

Photonic processors are described. The photonic processors described herein are configured to perform matrix multiplications (e.g., matrix vector multiplications). Matrix multiplications are broken down in scalar multiplications and scalar additions. Some embodiments relate to devices for performing scalar additions in the optical domain. One optical adder, for example, includes an interferometer having a plurality of phase shifters and a coherent detector. Leveraging the high-speed characteristics of these optical adders, some processors are sufficiently fast to support clocks in the tens of gigahertz of frequency, which represent a significant improvement over conventional electronic processors.

Photonic processors are described. The photonic processors described herein are configured to perform matrix multiplications (e.g., matrix vector multiplications). Matrix multiplications are broken down in scalar multiplications and scalar additions. Some embodiments relate to devices for performing scalar additions in the optical domain. One optical adder, for example, includes an interferometer having a plurality of phase shifters and a coherent detector. Leveraging the high-speed characteristics of these optical adders, some processors are sufficiently fast to support clocks in the tens of gigahertz of frequency, which represent a significant improvement over conventional electronic processors.

Optical circuits support reconfigurable spatial rearrangement (also referred to as “spatial multiplexing”) for a group of photons propagating in waveguides. According to some embodiments, a set of 2×2 muxes can be used to rearrange a pattern of photons on a first set of waveguides into a usable input pattern for a downstream optical circuit.

Optical circuits support reconfigurable spatial rearrangement (also referred to as “spatial multiplexing”) for a group of photons propagating in waveguides. According to some embodiments, a set of 2×2 muxes can be used to rearrange a pattern of photons on a first set of waveguides into a usable input pattern for a downstream optical circuit.

An expanded Bell state generator can generate a Bell state on four output modes of a set of m output modes, where m is greater than four. Some expanded Bell state generators can receive inputs on any four of a set of 2m input modes. Subsets of the m output modes can be multiplexed to reduce the number of modes to four. According to some embodiments, a set of 2×2 muxes can be used to rearrange the output modes prior to reducing the number of modes.

A technique is described to deterministically tune the emission frequency of individual semiconductor photon sources, for example quantum dots. A focused laser is directed at a film of material that changes form when heated (for example, a phase change material that undergoes change between crystal and amorphous forms) overlaid on a photonic membrane that includes the photon sources. The laser causes a localized change in form in the film, resulting in a change in emission frequency of a photon source.