Psiquantum Corp.

Eric Dudley

Faraz Najafi

Mark G Thompson

Koustuban Ravi

Vimal Kumar Kamineni

Yong Liang

Jin Yao

Mihai Dorian Vidrighin

Mark Thompson

Ann Melnichuk

Stanley Burgos

Bryan Park

Mehdi Jadidi

A notch filter circuit includes a wavelength demultiplexer, a first pump rejection filter coupled to the wavelength demultiplexer, and a second pump rejection filter coupled to the wavelength demultiplexer. The notch filter circuit also includes a first notch filter arm coupled to the first pump rejection filter and including a first chain of asymmetric Mach-Zehnder interferometers (MZIs) and a second notch filter arm coupled to the second pump rejection filter and including a second chain of asymmetric MZIs.

System for integrated photonic notch filter

An example photon counting device includes one or more unit cells. Each unit cell includes one or more superconducting components. Each unit cell also includes a current dynamics control element coupled in series with the one or more superconducting components. Each unit cell further includes a transistor having a superconducting gate element that is coupled with the one or more superconducting components and a channel element that is electrically insulated from the superconducting gate element, where the channel element has a first resistance while the superconducting gate element is in a superconducting state and a second resistance while the superconducting gate element is in a non-superconducting state. The photon counting device further includes a bias current source coupled to the one or more unit cells and a waveguide optically coupled to the one or more unit cells.

Scalable photon number resolving photon detector

A device includes a spot size converter on a substrate. The substrate includes an optical fiber alignment structure formed thereon. The spot size converter is aligned with the optical fiber alignment structure. The spot size converter includes an oxide layer that has a first refractive index and includes a tapered section such that a first end of the spot size converter is smaller than a second end of the spot size converter. The spot size converter also includes a waveguide core in the oxide layer. The waveguide core is tapered and is smaller at the first end than at the second end of the spot size converter. The spot size converter further includes a cladding layer surrounding the oxide layer, the cladding layer having a second refractive index lower than the first refractive index of the oxide layer.

Single photon interconnect employing low index cladding spot size converter

An optical device includes a substrate, a dielectric layer on the substrate, a waveguide within the dielectric layer, a light sensitive component (e.g., a photodetector) in the dielectric layer and coupled to the waveguide, and a plurality of light isolation structures in at least one of the substrate or the dielectric layer and configured to prevent stray light from reaching the light sensitive component. In some embodiments, a light isolation structure in the plurality of light isolation structures includes two opposing sidewalls and a filling material between the two opposing sidewalls. The two opposing sidewalls include an optical isolation layer. The filling material is characterized by a coefficient of thermal expansion (CTE) matching a CTE of at least one of the substrate or the dielectric layer.

Isolation of waveguide-integrated detectors using a back end of line process

A method includes fabricating a device including a first dielectric layer, an optical waveguide in the first dielectric layer, and a superconducting circuit in the first dielectric layer and on the optical waveguide. The method also includes forming a sacrificial structure on the first dielectric layer, the sacrificial structure aligned with the superconducting circuit, depositing a second dielectric layer on the sacrificial structure, and cutting an opening in the second dielectric layer to expose the sacrificial structure. The method further includes wet etching the sacrificial structure through the opening and sealing the opening in the second dielectric layer with a third dielectric layer to form a micro-channel between the first dielectric layer and the second dielectric layer.

Cryogenic microfluidic cooling for photonic integrated circuits

A photon counting device includes unit cells, a bias current source coupled to the unit cells, and a waveguide coupled to the unit cells. Each unit cell includes photodetector(s). Each photodetector includes superconducting component(s) and a transistor. The transistor includes a superconducting gate that is coupled in parallel with the photodetector(s), and a channel that is electrically isolated from the superconducting gate. For each unit cell, a photodetector is optically coupled to the waveguide. A superconducting component is configured to transition from the superconducting state to the non-superconducting state in response to a photon being incident upon the superconducting component while the superconducting component receives at least a portion of bias current output from the bias current source. The superconducting gate of the unit cell is configured to transition from the superconducting state to the non-superconducting state in response to the superconducting component transitioning to the non-superconducting state.

A method of resolving a number of photons received by a photon detector includes optically coupling a waveguide to a superconducting wire having alternating narrow and wide portions; electrically coupling the superconducting wire to a current source; and electrically coupling an electrical contact in parallel with the superconducting wire. The electrical contact has a resistance less than a resistance of the superconducting wire while at least one narrow portion of the superconducting wire is in a non-superconducting state. The method includes providing to the superconducting wire, from the current source, a current configured to maintain the superconducting wire in a superconducting state in the absence of incident photons; receiving one or more photons via the waveguide; measuring an electrical property of the superconducting wire, proportional to a number of photons incident on the superconducting wire; and determining the number of received photons based on the electrical property.

Photon number resolving superconducting detector

A photonic switch includes a first waveguide including a first region extending between a first coupler section and a second coupler section and a second region extending between the second coupler section and a third coupler section. The photonic switch also includes a second waveguide including a first portion extending between the first coupler section and the second coupler section, the first portion including at least two first compensation sections each having a different waveguide width, and a second portion extending between the second coupler section and the third coupler section, the second portion including at least two second compensation sections each having a different waveguide width. The photonic switch further includes at least one variable phase-shifter disposed in at least one of the first waveguide or the second waveguide.

Interferometer filters with compensation structure

A Mach-Zehnder interferometer (MZI) filter comprising one or more passive compensation structures are described. The passive compensation structures yield MZI filters that are intrinsically tolerant to perturbations in waveguide dimensions and/or other ambient conditions. The use of n+1 waveguide widths can mitigate n different sources of perturbation to the filter. The use of at least three different waveguide widths for each Mach-Zehnder waveguide can alleviate sensitivity of filter performance to random width or temperature variations. A tolerance compensation portion is positioned between a first coupler section and a second coupler section, wherein the tolerance compensation portion includes a first compensation section having a second width, a second compensation section having a third width and a third compensation section having a fourth width, wherein the fourth width is greater than the third width and the third width is greater than the second width.

Techniques disclosed herein relate generally to photonic integrated circuits working at cryogenic temperatures. In one example, a device includes a substrate, a dielectric layer on the substrate, an optical waveguide in the dielectric layer, a superconducting circuit in the dielectric layer and coupled to the optical waveguide, and a micro-channel in the dielectric layer and adjacent to the superconducting circuit. The micro-channel is aligned with the superconducting circuit and is configured to conduct a liquid at a cryogenic temperature to locally cool the superconducting circuit.

A photon detector is provided. The photon detector includes a superconducting wire having a plurality of alternating narrow and wide portions; a current source electrically-coupled to the superconducting wire and configured to supply the superconducting wire with electrical current; and an optical waveguide optically coupled to the plurality of narrow portions of the superconducting wire.

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Sacramento, CA, United States of America

Eric Dudley