Kinetic inductance compensated photon detectors

Abstract

A photonic integrated circuit and method. A waveguide is configured to propagate one or more photons. A photon-sensitive portion of a superconducting wire proximate to the waveguide is configured to transition from a superconducting state to a non-superconducting state in response to detection of a. photon within the waveguide. A low resistance metal structure is connected to a first lead and a second lead, the first lead being connected to one end of the photon-sensitive portion and the second lead being connected to another end of the photon-sensitive portion. The low resistance metal structure is separated from the waveguide to create a gap between a portion of the low resistance metal structure and the photon-sensitive portion. A resistor is connected between the first lead, and a middle section of the low resistance metal structure such that current through the resistor causes a short circuit to bypass the photon-sensitive portion.

Description

Docket No. 6224.003WD1 / Client Ref. No. PSIQ-507WD1KINETIC INDUCTANCE COMPENSATED PHOTON DETECTORSCLAIM OF PRIORITY

[0001] This application claims the benefit of priority to U.S. Patent Application Serial No. 63 / 441,147, filed on January 25, 2023, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to superconducting devices, and more particularly to devices utilizing both superconducting and non- superconducting states and kinetic inductance reducing architectures.BACKGROUND

[0003] Photon detectors are key components in many electronic devices. High-performance ultra-sensitive photon detectors that are capable of detecting individual photons can be used in different applications such as optical communications, medical diagnostics, quantum optics, and quantum optics-based information processing applications such as quantum-based communication schemes and optical quantum computing.

[0004] Superconductors are materials capable of operating in a superconducting state with zero electrical resistance under particular conditions. Superconductors are also capable of operating in a non- superconducting (conducting) state. Because of many useful properties of superconductors, photon detectors based on superconductors exhibit superior performance over conventional light detectors, such as photodiodes.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] T he following description includes discussion of figures having illustrations given by way of example of implementations of embodiments of the disclosure. The drawings should be understood by way of example, and not by way of limitation. As used herein, references to one or more "embodiments" are to be understood as describing a particular feature.Docket No. 6224.003WO1 / Client Ref. No. PSIQ-507WO1structure, or characteristic included in at least one implementation of the inventive subject matter. Thus, phrases such as "in one embodiment" or "in an alternate embodiment" appearing herein describe various embodiments and implementations of the inventive subject matter, and do not necessarily all refer to the same embodiment. However, they are also not necessarily mutually exclusive. To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure (“FIG.”) number in which that element or act is first introduced.

[0006] FIG. 1 shows a top view of a photon architecture, in accordance with some example embodiments.

[0007] FIG. 2A shows an upper side perspective view of a kinetic inductance compensated photon detector architecture, in accordance with some example embodiments.

[0008] FIG. 2B shows an upper side perspective view of an equivalent circuit schematic of the kinetic inductance compensated photon detector architecture of FIG. 2 A, in accordance with some example embodiments.

[0009] FIG. 3 A shows an upper side perspective view of a compensated photon detector in operation in a first configuration state, in accordance with some example embodiments.

[0010] FIG. 3B shows an upper side perspective view of a compensated photon detector in operation in a second configuration state, in accordance with some example embodiments.

[0011] FIG. 4 shows an upper side perspective view of a multiple compensated photon detector architecture, where the units are configured in a series to detect multiple individual photons, in accordance with some example embodiments.

[0012] FIG. 5A shows a front view of a compensation architecture, in accordance with some example embodiments.

[0013] FIG. 5B shows a field profile log of the compensation architecture of FIG. 5 A, in accordance with some example embodiments.

[0014] FIG. 6A shows a front view of a split compensation architecture, in accordance with some example embodiments.Docket No. 6224.003WO1 / Client Ref. No. PSIQ-507WO1

[0015] FIG. 6B shows a perspective view of the split compensation architecture of FIG. 6 A, in accordance with some example embodiments.

[0016] FIG. 7 shows a front view of a vertical split compensation architecture, in accordance with some example embodiments.

[0017] FIG. 8 shows a top view of a Superconducting Nanowire Avalanche Photodetector (SNAP) architecture, in accordance with some example embodiments.

[0018] FIG. 9 illustrates operations of an example method for detection of light in a photonic integrated circuit, in accordance with some example embodiments.

[0019] Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the disclosure is provided below, followed by a more detailed description with reference to the drawings.DETAILED DESCRIPTION

[0020] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide an understanding of various embodiments of the inventive subject matter. It will be evident, however, to those skilled in the art, that embodiments of the inventive subject matter may be practiced without these specific details. In general, well-known instruction instances, structures, and techniques are not necessarily shown in detail.

[0021] A photon number resolving detector that can operate at high detection efficiency to detect multiple photons can create a large footprint (e.g., large superconducting layout footprint) which will exhibit a large total kinetic inductance. Kinetic inductance is the manifestation of the inertial mass of mobile charge carriers (e.g., in a superconductor) in alternating electric fields as an equivalent series inductance. In particular, for example, in superconductive material, kinetic inductance is how the current flow's in the material, which can be affected by small or microscopic details (e.g..Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1penetration depth of the superconducting material, thickness of the superconductor film in a superconducting individual photon detector, or photon number resolving detectors). Having high kinetic inductance in a given detector architecture can limit the photodetector repetition rate and readout signal amplitudes in the given photon detection architecture.

[0022] To address the foregoing, a compensated photon detector is configured with a single superconducting detection wire per unit of a given compensated photon detector and a resistor to bypass the current in response to detections, which thereby significantly decreases the amount of kinetic inductance (e.g., by a factor two or more) of the photonic device. The example photon detectors described herein are suitable for inclusion in a photonic integrated circuit (PIC) or another suitable photonic device.

[0023] The reduction of kinetic inductance achieved by some examples described herein is significant and can decrease all the time scales that would otherwise limit high repetition rates of the photon detection architecture. In some example embodiments, quantum optics-based logic devices require very high repetition rates to enable detection of fast consecutive cliques (e.g., due to rapidly impinging consecutive photons). If these time scales are not fast enough, the quantum optics logic device will not be capable of operating at a fast enough repetition rate to function, which can lead to degraded readout performance. The following are time scale relations of the compensated photon detector that are reduced by reducing the kinetic inductance: first, the photon-number-resolving detector (PNRD) reset time, which is proportional to the kinetic inductance divided by the readout impedance; second, the discharge time of the readout circuit capacitors, which is proportional to: the square root of (the capacitance times the kinetic inductance); and third, resistor-capacitor (RC) timescales, which is proportional to: the largest resistance component's resistance times the kinetic inductance.

[0024] FIG. 1 shows a photon detector architecture 100, in accordance with some example embodiments. In the example illustrated, a superconducting wire of the architecture 100 has a wide non-photon-sensitive portion 110, and further has a narrow photon-sensitive portion 120 that is configured toDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1detect light that is propagating in a waveguide 125. In particular, the narrow photon-sensitive portion 120 can operate as one or more photon detection points 115 that can detect individual photons by transitioning from a super conductive state to a non-super conductive state, in accordance with some example embodiments. The photon detector architecture 100 includes a resistor 105 to bypass the current in response to photon detections.

[0025] FIG. 2A shows a kinetic inductance compensated photon detector architecture 200, in accordance with some example embodiments. In the example illustrated, the superconducting wire has a wide non-photon sensitive portion 210 that is connected to a previous cell 228 (e.g., another instance of the kinetic inductance compensated photon detector architecture 200, depicted as a block in FIG. 2A). Further, the superconducting wire has a narrow photon sensitive portion 215 coupled at a first end to a first lead 232 and at a second end to a second lead 234 (shown in FIG. 2A as portions of the superconducting wire). The narrow photon sensitive portion 215 functions as a detector 222 to detect light (e.g., individual photons) that propagates in the waveguide 205. In response to photon detection, the narrow photon sensitive portion 215 (e.g., detector 222) transitions from a superconducting state to a non-superconducting state which causes a current to be transmitted to a low resistance metal structure 225. The low resistance metal structure 225 is two-dimensionally separated (e.g., vertically distanced from) and connected (via a middle section 238 of the low resistance metal structure 225) to a finite resistance resistor 220, in accordance with some example embodiments. The resistor 220 can function to short the detector 222 and a segment 236 of the low resistance metal structure 225, as further discussed below.

[0026] In some example embodiments, the low' resistance metal structure 225 is positioned far enough away from the waveguide 205 to ensure minimization of errant photon absorption by the detector 222. Thus, the low resistance metal structure 225 is separated from the waveguide 205 to create a gap between at least a portion of the low7resistance metal structure 225 and the photon-sensitive portion 215: in the illustrated example, the waveguide 205 is in a first layer of the photonic integrated circuit, the photon-sensitive portion 215 is in a second layer of the photonic integrated circuit The lowDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1resistance metal structure 225 provides readout circuitry and is further connected to the next cell 227 (e.g. another instance of the kinetic inductance compensated photon detector architecture 200, shown as a block in FIG. 2A).

[0027] FIG. 2B illustrates an equivalent circuit schematic 230, functionally equivalent to the kinetic inductance compensated photon detector architecture 200 of FIG. 2 A, for clarity.

[0028] In some example embodiments, in operation of the kinetic inductance compensated photon detector architecture 200, when the detector 222 is idle, in a superconductive state, all the current is configured to pass through the detector 222 (e.g., narrow photon sensitive portion 215 of the superconducting wire), and through a full length of a low resistive path (e.g., low resistance metal structure 225). In response to a photon being absorbed by the detector 222, the narrow photon sensitive portion 215 becomes very resistive and all of the current will pass through the resistor 220, thereby causing a short circuit to occur, bypassing the detector 222 and the segment 236 of the low resistance metal structure 225, which decreases kinetic inductance. When the current passes through the resistor 220, a finite voltage on the resistor 220 is then measured to record detection of one or more individual photons. In some example embodiments, the voltage measured across the resistor 220 is recorded or stored as a data value in a memory circuit of the PIC (not shown) coupled to the resistor 220 via a readout circuit.

[0029] FIG. 3 A and FIG. 3B show a compensated photon detector in operation, in accordance with some example embodiments. In a first configuration state 300 shown in FIG. 3A, the kinetic inductance compensated photon detector architecture 200 is idle, and as illustrated by the arrows, the current can pass through the detector 222 and through a full length of the low resistance metal structure 225. In a second configuration state 350 shown in FIG. 3B, a photon has been absorbed by the detector 222, and in response the current (IDC) bypasses the detector 222 and instead is directed through the resistor 220 to a portion of the low resistance metal structure 225.Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1

[0030] FIG. 4 shows a multiple compensated photon detector architecture 400, where the units are configured in a series to detect multiple individual photons, according to some example embodiments. In addition to the detector 222, resistor 220, and other components labelled in FIG. 4, each further unit or cell of the multiple compensated photon detector architecture 400 includes a further detector 222, a further resistor 220, and so on. In operation, when multiple photons are absorbed by individual units in the multiple compensated photon detector architecture 400, due to the resistor and low resistance structure arrangement, a voltage proportional to the number of cells will then be measured to indicate the quantity of photons that have been detected in the waveguide (not depicted) that passes by each unit of the multiple compensated photon detector architecture 400, while kinetic inductance is reduced per unit and thereby significantly reduced for the overall architecture 400 thereby enabling high repetition rates and accurate individual photon readouts. Thus, one photon may be absorbed by the detector 222, and another photon may be absorbed by a further detector of another cell (e.g., previous cell 228 or next cell 227), with the voltages across the resistors 220 of the various cells being measured to determine how many photons have been absorbed in total.

[0031] In some example embodiments, a superconducting nanowire avalanche photodetector (SNAP) comprises a plurality of superconducting nanowires (e.g., between two and ten nanowires) coupled in parallel to one another, such that each nanowire functions as a narrow photon sensitive portion 215 of a superconducting wire as described above. In some example embodiments, a SNAP provides amplification of a detection current that is produced in response to detection (e.g., absorption) of the photon, and can increase the signal to noise ratio of a detection signal. At a high level, if a single photons strikes one of the in-parallel nanowires, the nanowire absorbs a photon and the photon absorption region or spot transitions to a non- superconducting state (e.g., a hotspot). The hotspot in the nanowire that absorbed the photon incurs higher resistance overall, and thereby more current is directed to another in-parallel nanowire as part of an amplified current signal, which then causes another hotspot from current crowding in the other nanowire, causing the other nanowire to transition to a non¬Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1superconducting state, which (possibly along with the transition of one or more additional in-parallel nanowires) increases resistance which can be read out as an amplified detection at that SNAP device. This cascade of transitions of multiple nanowires may be referred to as a SNAP avalanche process.

[0032] In some example embodiments, the SNAP device is configured such that it is at an angle to the waveguide, such as an orthogonal or nearly orthogonal angle to the waveguide that propagates the photons.

[0033] FIG. 5A to FIG. 7 discuss a kinetic inductance minimizing architecture implementing one or more superconducting nanowire avalanche photodetectors, in accordance with some example embodiments. High detection efficiency photon number resolving detectors or multiple photons will incur a large total kinetic inductance that can limit the detectors' repetition rate and readout signal amplitude.

[0034] In some example embodiments, two or more nanowires (e.g., niobium nitride (NbN) nanowires) can be configured in a structural support sandwich architecture (e.g., between Aluminum Nitride layers) to form a SNAP-like device that can be arranged in different configurations, such as vertical (normal to) the plane of the waveguide that propagates the light, or placed on either side of the waveguide that propagates the light for detection to reduce kinetic inductance of the photon detector.

[0035] FIG. 5A shows a compensation architecture 500, in accordance with some example embodiments. In the architecture 500, the plurality of nanowire 515A and 515B are connected in parallel to an electrical trace 507 of readout resistor 505. The two sides of the electrical trace 507 function analogously to the first, lead 232 and second lead 234, respectively, described above with reference to the kinetic inductance compensated photon detector architecture 200. The portion of the electrical trace 507 projecting upward from the sandwich structure including nanowire 515A and 515B and coupled to readout resistor 505 functions analogously to the low resistance metal structure 225 of the kinetic inductance compensated photon detector architecture 200. In the example of FIG. 5 A, the nanowire 515A and 515B are sandwiched or otherwise supported by one or more structuralDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1layers, such as aluminum nitride layer 520A and aluminum nitride layer 520B, where a cladding or oxide layer 510 is on top of a top layer that has the top nanowire (e.g., “top” from the perspective of FIG. 5 A). As shown in the field profile log graph 535 in FIG. 5B, light propagates down the waveguide core which causes a field that distributes and attenuates throughout the field profile log graph 535 of FIG. 5B. As further shown in the field profile log graph 535, an approximate uniform field distribution over the two nanowire 515A and 515B (e.g., two to N nanowires, in accordance with some example embodiments) indicates equal probability of distribution in each nanowire.

[0036] On a side opposite of the cladding or oxide layer 510, coupling material 525 is positioned closest to a waveguide core 530 that, propagates the light. In some example embodiments, the coupling material 525 and the waveguide core 530 are composed of the same material (e.g., silicon, silicon nitride). As photons propagate down the waveguide core 530 (and a z-axis direction as illustrated in FIG. 5A), one or more of the photons can be absorbed by one of the nanowire 515 A or 515B that are in the vertical configuration, and undergo a SNAP avalanche process to cause amplified current to be transmitted to the readout resistor 505, thereby reducing the kinetic inductance of the compensation architecture 500. In some example embodiments, the waveguide core 530 is located in a first layer of a PIC, and the plurality of superconducting nanowire 515A and 515B are located in a second layer of the PIC adjacent to the first layer. The first nanowire 515 A and the second nanowire 515B are vertically offset (along the Y-axis) within the second layer, such that the first nanowire 515 A is closer to the waveguide than the second nanowire 515B. The waveguide core 530 is configured to propagate the photons along a photon propagation axis defined by the Z-axis in FIG. 5 A extending into and out of the plane of the drawing.

[0037] FIG. 6A shows a split compensation architecture 600 in accordance with some example embodiments. In the example split compensation architecture 600 of FIG. 6A, the nanowire 515A and 515B are arranged in separate sandwich structures 605 and 610 (e.g., sandwiched by one or more layers of aluminum nitride for structural support and electrical and optical properties). As illustrated, a first nanowire sandwich structure 605 isDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1separated from a second nanowire sandwich structure 610 but still in a SNAP configuration due to the lower portion of the electrical trace 507 that provides a low resistance route for current to avalanche from a first detecting wire to a second “tripped” ware that receives the advancing current, thereby reducing kinetic inductance and improving readout signal and repetition rate.

[0038] FIG. 6B shows a perspective view 650 of the split compensation architecture 600, showing arrangement of the first nanowire sandwich structure 605, second nanowire sandwich structure 610, and electrical trace 507 in relation to the Z-axis, whereby the Z-axis substantially defines a longitudinal axis of the waveguide core 530.

[0039] FIG. 7 shows a vertical split compensation architecture 700, in accordance with some example embodiments. In the architecture 700, a first nanowire sandwich structure 705 is connected by two leads to two respective electrical traces to a second nanowire sandwich structure 710, such that when one of the nanowire sandwich structures is tripped (e.g., a photon is absorbed), current is directed or avalanched towards one of more remaining un-tripped nanowire sandwich structures, thereby reducing kinetic inductance and improving readout signal and repetition rate, in accordance with some example embodiments.

[0040] FIG. 8 illustrates a photodetector 800 in accordance with some example embodiments. In some embodiments, the photodetector 800 is a Superconducting Nanowire Avalanche Photodetector (SNAP) that includes two or more superconducting components (e.g., two, three, four, or five, or a number typically no more than 10 superconducting components 805) coupled in parallel to one another. In some embodiments, each superconducting component 805 is a superconducting nanowire. In this example, the SNAP includes a first superconducting component 805A and a second superconducting component 805B coupled in parallel to one another. Each superconducting component 805 of the photodetector 800 is coupled (e.g., optically coupled) to a waveguide 810 and acts as an independent (e.g., isolated) photodetector that absorbs a portion (e.g., less than all, a subset, a fraction) of light propagating in the waveguide 810. In some embodiments, each superconducting component 805 of the SNAP has a predeterminedDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1length orthogonally overlapping the waveguide 810. For example, the length, LI, of the superconducting components 805A and 805B orthogonally overlapping the waveguide 810 may be approximately 2 μm, and typically is less than 5 μm or 10 μm. The short length (e.g., ~2 μm) of the superconducting components 805 increases yield and decreases dark counts due to light scattering.

[0041] The SNAP also includes junctions 815A and 815B (e.g., a compact junction) that are disposed between the superconducting components 805 and the rest of the circuit (e.g., the rest of the photon counting device). For example, the first superconducting components 805A and 805B are disposed between junctions 815A and 815B.

[0042] FIG. 9 illustrates an example method 900 for detection of light in a photonic integrated circuit. Whereas the method 900 is described with reference to the example device architectures described herein, it will be appreciated that in various example embodiments the method 900 may be performed by any suitable photonic integrated circuit.

[0043] Although the example method 900 depicts a particular sequence of operations, the sequence may be altered without departing from the scope of the present disclosure. For example, some of the operations depicted may be performed in parallel or in a different sequence that does not materially affect, the function of the method 900, In other examples, different components of an example device or system that implements the method 900 may perform functions at substantially the same time or in a specific sequence.

[0044] According to some examples, the method 900 includes propagating one or more photons in a waveguide (e.g., waveguide 125, 205, or 810) at operation 902.

[0045] According to some examples, the method 900 includes absorbing the photons using a photon-sensitive portion of a superconducting wire (e.g., a narrow photon-sensitive portion of a superconducting wire, or a nanowire) at operation 904. The photon-sensitive portion of a superconducting wire is located proximate to the waveguide, as described above, to enable theDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1detection of one or a small number of photons propagating within the waveguide.

[0046] According to some examples, the method 900 includes the photon¬ sensitive portion transitioning from a superconducting state to a non- superconducting state at operation 906. As described above, when the one or more photons are detected by the photon-sensitive portion of the superconducting wire, the temperature of the photon-sensitive portion increases, rendering the photon-sensitive portion non-superconducting and creating a voltage gradient across the photon-sensitive portion, which is wired in parallel with a resistor. n examples using a SNAP architecture, such as those described above in FIG. 5A through FIG. 8, when a first nanowire (e.g., nanowire 515A) of a sandwich structure absorbs the one or more photons, a hotspot is formed in the first nanowire, raising its resistance and directing current through the other nanowires of the sandwich structure, thereby causing each other nanowire of the sandwich structure to transition from the superconducting state to the non-superconducting state. This in turn directs current through the resistor to the low resistance metal structure such that current bypass the plurality of nanowires and flows through the resistor (e.g., readout resistor 505).

[0047] According to some examples, the method 900 includes directing current through a resistor to a low resistance metal structure to cause a short circuit to bypass the photon-sensitive portion at operation 908. Because the photon-sensitive portion is wired in parallel with the resistor and the photon¬ sensitive portion is no longer superconducting, the voltage gradient created across the photon-sensitive portion drives the current through the resistor wired in parallel to the photon-sensitive portion. This effectively shorts the photon-sensitive portion and the segment of the low resistance metal structure wired in parallel with the resistor. In a SNAP architecture, the short circuit through the readout resistor bypasses the plurality of nanowires.

[0048] According to some examples, the method 900 includes detecting absorption of the one or more photons based on the current from the low resistance metal structure at operation 910. Because the resistor now hasDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1current flowing through it, it can be used as a readout resistor to measure the current, thereby detecting the absorption of the one or more photons.

[0049] In various example embodiments, method 900 may be performed more than once or by more than one photon-sensitive portion. For example, the multiple compensated photon detector architecture 400 may be used to perform method 900 at each of the cells, such that one or more of the cells absorbs the one or more photons and detects said absorption. In some cases, multiple instances of one or more photons are each absorbed by a different cell performing method 900. In other examples, the SNAP architectures of FIG. 5A through FIG. 7 may perform method 900 at each of the sandwich structures, or at one of the sandwich structures, to detect one or more instances of one or more photons propagating within the waveguide.

[0050] As described above, examples described herein may address one or more technical problems associated with detection of one photon or a small number of photons. In some examples, a photon detector may be provided that reduces kinetic inductance significantly and / or can decrease the time scales that would otherwise limit high repetition rates of the photon detection architecture. Other technical features may be readily apparent to one skilled in the art from the figures, descriptions, and claims herein.

[0051] Thus, in accordance with various examples described herein, devices and methods for detection of light in a photonic integrated circuit are provided.

[0052] The following are example embodiments:

[0053] Example 1 is a method for detection of light in a photonic integrated circuit, the method comprising: propagating one or more photons in a waveguide that is proximate to a photon-sensitive portion of a superconducting wire, the photon-sensitive portion being configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide, a low resistance metal structure being connected to a first lead and a second lead, the first lead being connected to one end of the photon-sensitive portion and the second lead being connected to another end of the photon-sensitive portion, the low resistance metal structure being separated from the waveguide toDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1create a gap between a portion of the low resistance metal structure and the photon-sensitive portion, and a resistor being connected between the first lead and a middle section of the low resistance metal structure such that current through the resistor causes a short circuit to bypass the photon¬ sensitive portion; absorbing the one or more photons using the photon¬ sensitive portion, the photon-sensitive portion transitioning from the superconducting state to the non-superconducting state in response to absorption of the one or more photons; and in response to absorption of the one or more photons using the photon-sensitive portion: directing current through the resistor to the low resistance metal structure such that the short occurs to bypass the photon-sensitive portion; and detecting absorption of the one or more photons by the photonic integrated circuit based on the current from the low resistance metal structure.

[0054] In Example 2, the subject matter of Example 1 includes, wherein: the photon-sensitive portion is one of a plurality of narrow portions of the superconducting wire proximate to the waveguide; and the superconducting wire comprises a plurality of wide non-photon-sensitive portions alternating with the plurality of narrow portions.

[0055] In Example 3, the subject matter of Example 2 includes, wherein: a further photon-sensitive portion of the plurality of photon-sensitive portions of the superconducting wire is configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide; a further low resistance metal structure is connected to a further first lead and a further second lead; the further first lead is connected to one end of the further photon-sensitive portion and the further second lead is connected to another end of the further photon-sensitive portion; the further low resistance metal structure is separated from the waveguide to create a gap between a portion of the further low resistance metal structure and the further photon-sensitive portion; and a further resistor is connected between the further first lead and a middle section of the further low resistance metal structure such that current through the further resistor causes a short circuit to bypass the further photon-sensitive portion; the method comprising: propagating a further one or more photons in the waveguide; absorbing the further one orDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1more photons using the further photon-sensitive portion, the further photon¬ sensitive portion transitioning from the superconductive state to the non-superconductive state in response to absorption of the further one or more photons; and in response to absorption of the further one or more photons using the further photon-sensitive portion: directing current through the further resistor to the further low resistance metal structure such that the short occurs to bypass the further portion; and detecting absorption of the further one or more photons by the photonic integrated circuit based on the current from the further low resistance metal structure.

[0056] In Example 4, the subject matter of Examples 1-3 includes, wherein: the waveguide is in a first layer of the photonic integrated circuit; and the low resistance metal structure is in a second layer of the photonic integrated circuit to create the gap between the portion of the low7resistance metal structure and the first, photon-sensitive portion.

[0057] In Example 5, the subject matter of Examples 1--4 includes, wherein: the detecting of the absorption of the one or more photons by the photonic integrated circuit based on the current from the low resistance metal structure comprises: recording a value of the current from the low7resistance metal structure as a data value to indicate absorption of the one or more photons by the photonic integrated circuit.

[0058] In Example 6, the subject matter of Examples 1-5 includes, wherein: the photon-sensitive portion of the superconducting wire is a first nanowire of a plurality of nanowires of the photonic integrated circuit; the waveguide is proximate to each nanowire of the plurality of nanowires; the first lead is connected to one end of each nanowire of the plurality of nanowires and the second lead is connected to another end of each nanowire of the plurality of nanowires, such that the plurality of nanowires are wired in parallel between the first lead and the second lead; each nanowire of the plurality of nanowires is configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide; and the transitioning of the first nanowire from the superconducting state to the non-superconducting state comprises forming a hotspot in the first nanowire; the method comprising: in response toDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1absorption of the one or more photons using the first nanowire: directing current through each other nanowire of the plurality of nanowires, thereby causing each other nanowire of the plurality of nanowires to transition from the superconducting state to the non-superconducting state; and directing current through the resistor to the low resistance metal structure such that the short occurs to bypass the plurality of nanowires.

[0059] In Example 7, the subject matter of Example 6 includes, wherein: the waveguide is proximate to a further plurality of nanowires operably coupled to a further low resistance metal structure and a further resistor to detect absorption of the one or more photons based on current from the further low resistance metal structure; and the plurality of nanowires and further plurality of nanowires are positioned on opposite sides of the waveguide.

[0060] Example 8 is a photonic integrated circuit comprising: a waveguide configured to propagate one or more photons; a photon-sensitive portion of a superconducting wire proximate to the waveguide, the photon-sensitive portion being configured to transition from a superconducting state to a non- superconducting state in response to detection of a photon within the waveguide, a low resistance metal structure connected to a first lead and a second lead, the first lead being connected to one end of the photon-sensitive portion and the second lead being connected to another end of the photon¬ sensitive portion, the low resistance metal structure being separated from the waveguide to create a gap between a portion of the low resistance metal structure and the photon-sensitive portion; and a resistor connected between the first lead and a middle section of the low resistance metal structure such that current through the resistor causes a short circuit to bypass the photon¬ sensitive portion.

[0061] In Example 9, the subject matter of Example 8 includes, wherein: the photon-sensitive portion is one of a plurality of narrow portions of the superconducting wire proximate to the waveguide, and the superconducting wire comprises a plurality of wide non-photon-sensitive portions alternating with the plurality of narrow portions.Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1

[0062] In Example 10, the subject matter of Example 9 includes, wherein: the plurality of photon-sensitive portions of the superconducting wire comprises a further photon-sensitive portion configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide; the photonic integrated circuit comprising: a further low resistance metal structure connected to a further first lead and a further second lead, the further first, lead being connected to one end of the further photon-sensitive portion and the further second lead being connected to another end of the further photon-sensitive portion, the further low resistance metal structure being separated from the waveguide to create a gap between a portion of the further low resistance metal structure and the further photon-sensitive portion; and a further resistor connected between the further first lead and a middle section of the further low resistance metal structure such that current through the further resistor causes a short circuit to bypass the further photon-sensitive portion.

[0063] In Example 11, the subject matter of Examples 8—10 includes, wherein: the waveguide is in a first layer of the photonic integrated circuit; and the low resistance metal structure is in a second layer of the photonic integrated circuit to create the gap between the portion of the low resistance metal structure and the first photon-sensitive portion.

[0064] In Example 12, the subject matter of Examples 8-11 includes, a memory circuit configured to record a value of the current from the low resistance metal structure as a data value to indicate absorption of the one or more photons by the photonic integrated circuit.

[0065] In Example 13, the subject matter of Examples 8—12 includes, wherein: the photon-sensitive portion of the superconducting wire is a first nanowire of a plurality of nanowires of the photonic integrated circuit; the waveguide is proximate to each nanowire of the plurality of nanowires; the first lead is connected to one end of each nanowire of the plurality of nanowires and the second lead is connected to another end of each nanowire of the plurality of nanowires, such that the plurality of nanowires are wired in parallel between the first lead and the second lead; each nanowire of the plurality of nanowires is configured to transition from a superconductingDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1state to a non-superconducting state in response to detection of a photon within the waveguide: and the transitioning of the first nanowire from the superconducting state to the non-superconducting state comprises: forming a hotspot in the first nanowire to transition the first nanowire from the superconducting state to the non-superconducting state; directing current through each other nanowire of the plurality of nanowires; and causing each other nanowire of the plurality of nanowires to transition from the superconducting state to the non-superconducting state.

[0066] In Example 14, the subject matter of Example 13 includes, wherein: the nanowires comprise niobium nitride (NbN).

[0067] In Example 15, the subject matter of Examples 13—14 includes, wherein: the plurality of nanowires are separated from each other by one or more structural layers.

[0068] In Example 16, the subject matter of Example 15 includes, wherein: the one or more structural layers comprise aluminum nitride.

[0069] In Example 17, the subject matter of Examples 13—16 includes, a further plurality of nanowires proximate to the waveguide and operably coupled to a further low resistance metal structure and a further resistor to detect absorption of the one or more photons based on current from the further low resistance metal structure, the plurality of nanowires and further plurality of nanowires being positioned on opposite sides of the waveguide.

[0070] Example 18 is a photonic integrated circuit comprising: a waveguide in a first layer of the photonic integrated circuit, the waveguide to propagate one or more photons along a photon propagation axis; and a plurality of superconducting wires in a second layer of the photonic integrated circuit, the second layer being adjacent to the first l yer in the photonic integrated circuit, the plurality of superconducting wires being at an angle to the waveguide that propagates the one or more photons, a first superconducting wire of the plurality of superconducting wires being electrically connected and parallel to a second superconducting wire of the plurality of superconducting wires such that absorption of a photon by the first superconducting wire causes current to be directed to the second superconducting wire to transition the second superconducting wire to a non¬Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1superconducting state, the first superconducting wire in the second superconducting wire being supported by one or more structural layers in the second layer of the photonic integrated circuit.[0071 J In Example 19, the subject matter of Example 18 includes, wherein the first superconducting wire is sandwiched between two structural layers in the second layer of the photonic integrated circuit.

[0072] In Example 20, the subject matter of Examples 18—19 includes, wherein the first layer and the second layer are adjacent to each other in a vertical direction, and wherein the first superconducting wire and the second superconducting wire are vertically offset within the second layer, such that the first superconducting wire is closer to the waveguide than the second superconducting wire.

[0073] Example 21 is at least one machine-readable medium including instructions that, when executed by processing circuitry, cause the processing circuitry' to perform operations to implement of any of Examples 1-20.

[0074] Example 22 is an apparatus comprising means to implement of any of Examples 1-20.

[0075] Example 23 is a system to implement of any of Examples 1-20.

[0076] Example 24 is a method to implement of any of Examples 1-20.

[0077] Other technical features and example embodiments may be readily apparent to one skilled in the art from the figures, descriptions, and claims herein.

[0078] It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first tuner could be termed a second tuner, and, similarly, a second tuner could be termed a first tuner, without departing from the scope of the various described embodiments. The first tuner and the second tuner are both tuners, but they are not the same tuner.

[0079] The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodimentsDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0080] As used herein, the term “if” is, optionally, construed to mean “when” or “upon” or “in response to determining” or “in response to detecting” or “in accordance with a determination that,” depending on the context.

[0081] The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the scope of the claims to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen in order to best explain the principles underlying the claims and their practical applications, to thereby enable others skilled in the art to best use the embodiments with various modifications as are suited to the particular uses contemplated.

Claims

Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1CLAIMSWhat is claimed is:

1. A method for detection of light in a photonic integrated circuit, the method comprising:propagating one or more photons in a waveguide that is proximate to a photon-sensitive portion of a superconducting wire,the photon-sensitive portion being configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide,a low resistance metal structure being connected to a first lead and a second lead,the first lead being connected to one end of the photon¬ sensitive portion and the second lead being connected to another end of the photon-sensitive portion,the low resistance metal structure being separated from the waveguide to create a gap between a portion of the low resistance metal structure and the photon-sensitive portion, anda resistor being connected between the first lead and a middle section of the low resistance metal structure such that current through the resistor causes a short circuit to bypass the photon-sensitive portion;absorbing the one or more photons using the photon-sensitive portion, the photon-sensitive portion transitioning from the superconducting state to the non-superconducting state in response to absorption of the one or more photons; andin response to absorption of the one or more photons using the photon-sensitive portion:directing current through the resistor to the low resistance metal structure such that the short bypasses the photon-sensitive portion; anddetecting absorption of the one or more photons by the photonic integrated circuit based on the current from the low resistance metal structure.Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO12. The method of claim 1, wherein:the photon-sensitive portion is one of a plurality of narrow portions of the superconducting wire proximate to the waveguide; andthe superconducting wire comprises a plurality of wide non-photon- sensitive portions alternating with the plurality of narrow portions,3. The method of claim 2, wherein:a further photon-sensitive portion of the plurality of photon-sensitive portions of the superconducting wire is configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide;a further low resistance metal structure is connected to a further first lead and a further second lead;the further first lead is connected to one end of the further photon¬ sensitive portion and the further second lead is connected to another end of the further photon-sensitive portion;the further low resistance metal structure is separated from the waveguide to create a gap between a portion of the further low resistance metal structure and the further photon-sensitive portion; anda further resistor is connected between the further first lead and a middle section of the further low resistance metal structure such that current through the further resistor causes a short circuit to bypass the further photon-sensitive portion;the method comprising:propagating a further one or more photons in the waveguide; absorbing the further one or more photons using the further photon-sensitive portion, the further photon-sensitive portion transitioning from the superconductive state to the non- superconductive state in response to absorption of the further one or more photons; andin response to absorption of the further one or more photons using the further photon-sensitive portion:Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1directing current through the further resistor to the further low resistance metal structure such that the short bypasses the further portion, anddetecting absorption of the further one or more photons by the photonic integrated circuit based on the current from the further low resistance metal structure.

4. The method of claim 1, wherein:the waveguide is in a first layer of the photonic integrated circuit; and the low resistance metal structure is in a second layer of the photonic integrated circuit to create the gap between the portion of the low resistance metal structure and the first photon-sensitive portion.

5. The method of claim I, wherein:the detecting of the absorption of the one or more photons by the photonic integrated circuit based on the current from the low resistance metal structure comprises:recording a value of the current from the low resistance metal structure as a data value to indicate absorption of the one or more photons by the photonic integrated circuit.

6. The method of claim 1, wherein:the photon-sensitive portion of the superconducting wire is a first nanowire of a plurality of nanowires of the photonic integrated circuit;the waveguide is proximate to each nanowire of the plurality of nanowires;the first lead is connected to one end of each nanowire of the plurality of nanowires and the second lead is connected to another end of each nanowire of the plurality of nanowires, such that the plurality of nanowires is wired in parallel between the first lead and the second lead;each nanowire of the plurality of nanowires is configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide; andDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1the transitioning of the first nanowire from the superconducting state to the non-superconducting state comprises forming a hotspot in the first nanowire;the method comprising:in response to absorption of the one or more photons using the first nanowire:directing current through each other nanowire of the plurality of nanowires, thereby causing each other nanowire of the plurality of nanowires to transition from the superconducting state to the non-superconducting state; and directing current through the resistor to the low resistance metal structure such that the short bypasses the plurality of nanowires.

7. The method of claim 6, wherein:the waveguide is proximate to a further plurality of nanowires operably coupled to a further low resistance metal structure and a further resistor to detect absorption of the one or more photons based on current from the further low resistance metal structure; andthe plurality of nanowires and further plurality of nanowires are positioned on opposite sides of the waveguide.

8. A photonic integrated circuit comprising:a waveguide configured to propagate one or more photons;a photon-sensitive portion of a superconducting wire proximate to the waveguide, the photon-sensitive portion being configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide;a low resistance metal structure connected to a first lead and a second lead, the first lead being connected to one end of the photon-sensitive portion and the second lead being connected to another end of the photonsensitive portion, the low resistance metal structure being separated from the waveguide to create a gap between a portion of the low resistance metal structure and the photon-sensitive portion; andDocket No. 6224.003W01 / Client Ref. No. PSIQ-507WO1a resistor connected between the first lead and a middle section of the low resistance metal structure such that current through the resistor causes a short circuit to bypass the photon-sensitive portion.

9. The photonic integrated circuit of claim 8, wherein:the photon-sensitive portion is one of a plurality of narrow portions of the superconducting wire proximate to the waveguide; andthe superconducting wire comprises a plurality of wide non-photon- sensitive portions alternating with the plurality of narrow portions.

10. The photonic integrated circuit of claim 9, wherein:the plurality of photon-sensitive portions of the superconducting wire comprises a further photon-sensitive portion configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide;the photonic integrated circuit comprising:a further low resistance metal structure connected to a further first lead and a further second lead, the further first lead being connected to one end of the further photon-sensitive portion and the further second lead being connected to another end of the further photon-sensitive portion, the further low resistance metal structure being separated from the waveguide to create a gap between a portion of the further low resistance metal structure and the further photon-sensitive portion; anda further resistor connected between the further first lead and a middle section of the further low7resistance metal structure such that current through the further resistor causes a short circuit to bypass the further photon-sensitive portion.

11. The photonic integrated circuit of claim 8, wherein:the waveguide is in a first layer of the photonic integrated circuit; and the low resistance metal structure is in a second layer of the photonic integrated circuit to create the gap between the portion of the low resistance metal structure and the first photon-sensitive portion.Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO112. The photonic integrated circuit of claim 8, further comprising:a memory circuit configured to record a value of the current from the low resistance metal structure as a data value to indicate absorption of the one or more photons by the photonic integrated circuit.

13. The photonic integrated circuit of claim 8, wherein:the photon-sensitive portion of the superconducting wire is a first nanowire of a plurality of nanowires of the photonic integrated circuit;the waveguide is proximate to each nanowire of the plurality of nanowires;the first lead is connected to one end of each nanowire of the plurality of nanowires and the second lead is connected to another end of each nanowire of the plurality of nanowires, such that the plurality of nanowires are wired in parallel between the first lead and the second lead;each nanowire of the plurality of nanowires is configured to transition from a superconducting state to a non-superconducting state in response to detection of a photon within the waveguide; andthe transitioning of the first nanowire from the superconducting state to the non-superconducting state comprises:forming a hotspot in the first nanowire to transition the first nanowire from the superconducting state to the non-superconducting state;directing current through each other nanowire of the plurality of nanowires; andcausing each other nanowire of the plurality of nanowires to transition from the superconducting state to the non-superconducting state.

14. The photonic integrated circuit of claim 13, wherein:the nanowires comprise niobium nitride (NbN).

15. The photonic integrated circuit of claim 13, wherein:the plurality of nanowires is separated from each other by one or more structural layers.Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO116. The photonic integrated circuit of claim 15, wherein:the one or more structural layers comprise aluminum nitride.

17. The photonic integrated circuit of claim 13, further comprising:a further plurality of nanowires proximate to the waveguide and operably coupled to a further low resistance metal structure and a further resistor to detect absorption of the one or more photons based on current from the further low resistance metal structure,the plurality of nanowires and further plurality of nanowires being positioned on opposite sides of the waveguide.

18. A photonic integrated circuit comprising:a waveguide in a first layer of the photonic integrated circuit, the waveguide to propagate one or more photons along a photon propagation axis; anda plurality of superconducting wires in a second layer of the photonic integrated circuit, the second layer being adjacent to the first layer in the photonic integrated circuit, the plurality of superconducting wires being at an angle to the waveguide that propagates the one or more photons, a first superconducting wire of the plurality of superconducting wires being electrically connected and parallel to a second superconducting wire of the plurality of superconducting wires such that absorption of a photon by the first superconducting wire causes current to be directed to the second superconducting wire to transition the second superconducting wire to a non- superconducting state, the first superconducting wire in the second superconducting wire being supported by one or more structural layers in the second layer of the photonic integrated circuit.

19. The photonic integrated circuit of claim 18, wherein the first superconducting wire is sandwiched between two structural layers in the second layer of the photonic integrated circuit.Docket No. 6224.003W01 / Client Ref. No. PSIQ-507WO120. The photonic integrated circuit of claim 18, wherein the first layer and the second layer are adjacent to each other in a vertical direction, and wherein the first superconducting wire and the second superconducting wire are vertically offset within the second layer, such that the first superconducting wire is closer to the waveguide than the second superconducting wire.

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