Quantum tomography and photon source optimization

Abstract

We provide a quantum computing system that includes a photon processing system that guides the highest quality photons, a photon analyzer, and a photon source module coupled to the photon processing system and the photon analyzer. [Solution] In the qubit entanglement subsystem 200, the photon source module 205 includes a plurality of photon sources 215a to 215n, each photon source nondeterministically generating one or more unentangled or entangled photons in response to the reception of a trigger signal 255. If two or more photon sources simultaneously generate photons in response to the trigger signal, one photon from the first photon pair is led to a photon processing system (resource state generator 110, photon detection system, or any other quantum computing device), and one photon from the second photon pair is led to a photon analyzer 260. During iterative operation, the photon analyzer analyzes photons from each of the plurality of photon sources to determine the characteristics of each photon source and uses this information to lead the highest quality photons to the photon processing system.

Description

Technical Field

[0001] Cross - reference to other applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 042,405, filed on June 22, 2020, and U.S. Non - Provisional Patent Application No. 17 / 351,101, filed on June 17, 2021, which are hereby incorporated by reference in their entirety for all purposes.

[0002]

[0002] The described embodiments generally relate to quantum computing. More particularly, the present embodiments relate to a photon source and the characterization of photons generated by the photon source.

Background Art

[0003]

[0003] Photon sources can be used in many different photonic quantum technologies where an ideal photon source deterministically generates photons. Such photon sources can be coherently coupled to approach a probability of 1 for each photon generation "cycle" and can be fabricated from multiple spatially or temporally multiplexed photon sources. During operation of the photon source, it would be beneficial to monitor the quality of the photons generated by each individual photon source and monitor the quality of each photon source to optimize the performance of the system.

Summary of the Invention

[0004] [[ID=****]]

[0004] The summary will be completed after the approval of the claims.

[0005] It should be noted that the 7 - digit tags - in the original text are not translated as there is no specific content provided for them. If there is any relevant information for these tags, please let me know and I will adjust the translation accordingly.

[0005] In some embodiments, the quantum computing system comprises a photon processing system, a photon analyzer, and a photon source module coupled to the photon processing system and the photon analyzer. The photon source module includes at least one photon source configured to emit one or more photons for each trigger signal, and a photon multiplexer configured to direct one or more emitted photons to the photon processing system or the photon analyzer. In various embodiments, the photon multiplexer directs one or more emitted photons to the photon processing system if the photon source module emits one photon for each trigger signal.

[0006]

[0006] In some embodiments, if the photon source module emits two or more photons for each trigger signal, the photon multiplexer directs one of the one or more emitted photons to a photon analyzer. In various embodiments, the photon processing system is a resource state generator. In some embodiments, one or more photons are entangled state photons. In some embodiments, at least one photon source is a plurality of spatially multiplexed photon sources. In various embodiments, at least one photon source is a plurality of temporally multiplexed photon sources.

[0007]

[0007] In some embodiments, the quantum computing system comprises a first photon source configured to produce one or more first photons, a second photon source configured to produce one or more second photons, and a photon multiplexer configured to direct one of the one or more first photons or one of the one or more second photons to a photon analyzer when the first and second photon sources simultaneously produce photons. In various embodiments, the device comprises a first photon source configured to produce a first photon pair in which each first photon pair includes a first signal photon and a first herald photon. A second photon source is configured to produce a second photon pair, each second photon pair including a second signal photon and a second herald photon. A first detector is configured to produce a first detection signal in response to the detection of a first herald photon. A second detector is configured to produce a second detection signal in response to the detection of a second herald photon. The detection logic circuit is configured to respond to the detection logic circuit, which receives first and second detection signals, by directing one of the first or second signal photons to a photon analyzer and the other of the first or second signal photons to a photon processing system.

[0008]

[0008] In some embodiments, the device further comprises a multiplexer that, in response to receiving one or more signals from a detection logic circuit, routes one of the first or second signal photons to a photon analyzer and the other of the first or second signal photons to a photon processing system. In various embodiments, the detection logic circuit directs the first and second signal photons based on the respective quality levels of the first and second signal photons. In some embodiments, in response to receiving the first or second signal photons, the photon analyzer determines one or more characteristics of the received signal photons.

[0009]

[0009] In some embodiments, one or more characteristics include color, jitter, wavelength, spectral width, or dispersion. In various embodiments during the iterative operation of the first and second photon sources, the photon analyzer determines one or more characteristics of the first signal photons produced by the first photon source and one or more characteristics of the second signal photons produced by the second photon source.

[0010]

[0010] In some embodiments, the photon analyzer compares one or more characteristics of the first signal photons with one or more characteristics of the second signal photons. In various embodiments, in response to the comparison, the photon analyzer sends a command to the photon processing system to receive more of the first signal photons than the second signal photons. In some embodiments, the device further includes a crossover switch that redirects the signal photons routed to the photon analyzer by the multiplexer to the photon processing system.

[0011]

[0011] In some embodiments, a method for generating photons comprises the steps of: generating a first photon pair using a first photon source, wherein the first photon pair includes a first signal photon and a first herald photon; generating a second photon pair using a second photon source, wherein the second photon pair includes a second signal photon and a second herald photon; generating a first detection signal in response to the detection of the first herald photon and generating a second detection signal in response to the detection of the second herald photon; one of the first or second signal photons being sent to a photon analyzer, and one of the first or second signal photons being routed to a photon processing system in response to a detection logic circuit receiving the first and second detection signals.

[0012]

[0012] In some embodiments, routing is performed by a multiplexer controlled by a detection logic circuit. In various embodiments, the detection logic circuit instructs the multiplexer to route the first and second signal photons based on the respective quality levels of the first and second signal photons. In some embodiments, in response to the reception of the first or second signal photons, the photon analyzer determines one or more characteristics of the received signal photons. In various embodiments, one or more characteristics include color, jitter, wavelength, spectral width, or dispersion. In some embodiments, during the iterative operation of the first and second photon sources, the photon analyzer determines one or more characteristics of the first signal photons and one or more characteristics of the second signal photons. In various embodiments, in response to the determination of one or more characteristics of the first and second signal photons, the photon analyzer sends a command to the photon processing system to receive more first signal photons than second signal photons.

[0013]

[0013] In some embodiments, the photon source comprises a plurality of photon sources, each configured to nondeterministically generate a pair of photons in response to the reception of a trigger signal, and each pair of photons includes a signal photon and a herald photon. Each of the plurality of photon detectors is coupled to each of the plurality of photon sources and is configured to generate a detection signal when it detects the herald photon of each generated pair of photons. Each of the plurality of photon routing switches is coupled to each of the photon sources and is configured to route each signal photon to a photon processing system or a photon analyzer. A photon detection logic circuit is configured to receive each respective detection signal and, in response to receiving two or more detection signals for each trigger signal, transmits control signals to the plurality of photon routing switches to route one signal photon to a photon analyzer and one signal photon to a photon processing system.

[0014]

[0014] In some embodiments, in response to the reception of a signal photon, the photon analyzer determines one or more characteristics of that signal photon. In various embodiments, after receiving multiple trigger signals, the photon analyzer determines one or more characteristics of signal photons produced by each of the multiple photon sources and ranks the quality of each photon source. In some embodiments, in response to the reception of two or more detection signals for each trigger signal, the photon analyzer transmits two or more signals that route signal photons from the highest quality photon sources to the photon processing system.

[0015]

[0015] To better understand the nature and merits of this disclosure, refer to the following description and accompanying drawings. However, it should be understood that each drawing is provided for illustrative purposes only and is not intended to define any limitation of the scope of this disclosure. Also, as a general rule, elements in different drawings are generally identical or at least similar in function or purpose unless it is evident from the description that elements in different drawings use the same reference numeral. [Brief explanation of the drawing]

[0016] [Figure 1] This is a simplified schematic diagram of a qubit entanglement subsystem according to an embodiment of the present disclosure. [Figure 2] This is a simplified schematic diagram of a qubit entanglement subsystem including a spatially multiplexed photon source according to an embodiment of the present disclosure. [Figure 3] This is a simplified schematic diagram of a qubit entanglement subsystem including a spatially multiplexed photon source according to an embodiment of the present disclosure. [Figure 4] This figure shows a method for generating photons for a photon processing system and analyzing excess photons according to an embodiment of the present disclosure. [Figure 5] Methods for generating and controlling the quality of signal photons for a photon processing system, according to some embodiments of the present disclosure. [Figure 6]This is a simplified schematic diagram of a qubit entanglement subsystem including a time-multiplexed photon source according to an embodiment of the present disclosure. [Figure 7] This is a simplified block diagram of an example of a linear optical quantum computer according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0017]

[0023] The techniques disclosed herein generally relate to applications in quantum computing. More specifically, the techniques disclosed herein relate to photon sources comprising multiple spatially or temporally multiplexed nondeterministic photon sources that guide photons to both a photon processing system and a photon analyzer. Using the results from the photon analyzer, photons produced by each of the multiple photon sources can be characterized, and the highest quality photons can be guided to the photon processing system. In additional embodiments, the photon analyzer can be used to check entanglement state parameters and identify defective photon sources to prevent them from transmitting photons to the photon processing system. The photon sources can generate either any type of unentangled or entangled photons. The photon processing system can be a resource state generator, a photon detection system, or any other quantum computing device. Various embodiments of the invention, including methods, processes, systems, devices, etc., are described herein. While the embodiments disclosed herein primarily relate to photon-based systems, the embodiments can be used in any system that uses entangled states.

[0018]

[0024] In one embodiment, multiple spatially multiplexed nondeterministic photon sources are configured to generate photon pairs in response to a trigger signal. In each photon source, photons can be generated nondeterministically in pairs (each pair including a signal photon and a herald photon). During the operation of the photon sources, "excess" photons are generated and can be sent to a photon analyzer to determine one or more properties of the photons and associated photon sources.

[0019]

[0025] In another embodiment, photons that are output from a resource state generator that can be non-entangled photons as well as entangled states of two or more photons (e.g., GHZ states, Bell pairs, etc.) can be analyzed by a photon analyzer. The analyzer can determine whether the resource state generator is functioning properly by analyzing the output photons and the entangled state of the photons.

[0020]

[0026] To better understand the features and aspects of the characterization of photons and photon sources according to the present disclosure, a further context of the present disclosure is provided in the following sections by describing some specific quantum computing architectures using photon analyzers according to embodiments of the present disclosure. These embodiments are, for example, merely examples, and other embodiments can be used in other quantum computing architectures.

[0021]

[0027] Figure 1 is a simplified block diagram of a qubit entanglement subsystem 100 of a linear optical quantum computer (LOQC) that can use the photon source disclosed herein, according to a particular embodiment. According to some embodiments, the qubit entanglement subsystem 100 can be used to generate qubits (e.g., photons) that include a plurality of unentangled photons and entangled states of two or more photons (e.g., GHz states, Bell pairs, etc.). As shown in Figure 1, the qubit entanglement subsystem 100 may include a photon source module 105 optically connected to a resource state generator 110. In one embodiment, the photon source module 105 can provide output photons to the resource state generator 110 by interconnecting waveguides 115. The resource state generator 110 can receive the output photons, convert them into one or more entangled photon states, and then output these entangled photon states to an output waveguide 120 for use by downstream circuits that can use the entangled states for further analysis. Both the photon source module 105 and the resource state generator 110 can be coupled to the classical computer system 125 so that the classical computer system 125 can communicate with and / or control the photon source module 105 and / or the resource state generator 110 (for example, via classical information channels 130a, 130b). A classical information channel 130c can communicate between the photon source module 105 and the resource state generator 110, and a classical communication channel 130d can communicate between the resource state generator 110 and downstream components.

[0022]

[0028] The entangled qubit subsystem 100 can include a first photon analyzer 140 coupled to the photon source module 105 and / or a second photon analyzer 145 coupled to the resource state generator 110. In some embodiments, the photon source module 105 and / or the resource state generator 110 can be nondeterministic and thus can generate excess photons and / or entangled photon states for a given generation cycle. The first and second photon analyzers 140, 145 are each configured to characterize these excess photons and / or entangled photon states and use the results for the improvement and / or diagnosis of the entangled qubit subsystem 100. More specifically, in some embodiments, the results from the first and second photon analyzers 140, 145 are used respectively to select the highest quality resources within the entangled qubit subsystem 100, preferentially use those resources for future operations, perform a diagnosis of the resources within the entangled qubit subsystem, perform quantum tomography on the photons and / or entangled photon states generated by the photon source and / or the resource state generator, verify that the entangled states generated by the photon source module and / or the resource state generator are correct, or perform other functions. One skilled in the art will recognize many variations, modifications, and alternative uses of the first and second photon analyzers 140, 145 respectively, and will understand that the photon analyzer can include any number of suitable photon components such as one or more photon detectors, optical filters, polarizers, birefringent elements, etc.

[0023] Photon source

[0029] In some embodiments, the photon source module 105 may be non-deterministic (sometimes called “stochastic”), such that a given pump pulse may or may not generate a photon pair. In some embodiments, coherent spatial and / or temporal multiplexing (referred herein to as “active” multiplexing) of several non-deterministic sources can be used to bring the probability of one mode being occupied during a given cycle closer to 1. Those skilled in the art will understand that many different active multiplexing architectures are possible that incorporate spatial and / or temporal multiplexing, some of which are described herein. For example, active multiplexing schemes can be used that utilize logarithmic trees, general-purpose Mach-Zehnder interferometers, multimode interferometers, chain sources, dump-to-pump chain sources, asymmetric polycrystalline single-photon sources, or any other type of active multiplexing architecture. In some embodiments, the photon source module 105 can employ active multiplexing schemes, such as quantum feedback control. In some embodiments described below, the use of multirail coding makes it possible to bring the probability of a bandwidth occupied by one mode during a given pulse cycle closer to 1, without active multiplexing.

[0024]

[0030] In one example of such a light source, the light source is driven by a pump (e.g., an optical pulse) coupled to an optical resonator, which can generate zero, one, or more photons through some nonlinear process (e.g., spontaneous four-wave mixing, second harmonic generation, etc.). As used herein, the term “trial” (also referred to herein as “cycle”) is used to refer to the act of driving a photon source with some kind of drive signal (e.g., a pump pulse) that can generate output photons nondeterministically (i.e., the probability that the photon source will generate one or more photons in response to the drive signal may be less than 1). In some embodiments, the apparent efficiency of the photon source can be increased by using multiple single-photon sources and multiplexing the outputs of multiple photon sources, as will be described in more detail below.

[0025]

[0031] The exact type of photon source used is not important; any type of source can be used, and any photon generation process can be used, such as spontaneous four-wave mixing (SPFW), spontaneous parametric down-conversion (SPDC), or any other process. Other classes of sources that do not necessarily require nonlinear materials, such as quantum dot sources, or those using atoms and / or artificial atomic systems such as color centers in crystals, can also be used. In some cases, the source may or may not be coupled to a photon cavity, for example, in the case of artificial atomic systems such as quantum dots coupled to a cavity. Other types of photon sources, such as optomechanical systems, also exist for SPFW and SPDC. In some examples, the photon source can emit multiple photons that are already in an entangled state, in which case the resource state generator 110 may not be necessary, or it may take the entangled state as input to generate an even larger entangled state. More specifically, the photon sources disclosed herein can generate any combination of single and multiple photons in unentangled and / or entangled states. Entangled photon states may include, but are not limited to, Bell states, GHZ states, or more generally, Greenberger-Horne-Zeilinger (GHZ) states of n qubits (multiple entangled states) (also known as "n-GHZ states"), or any other entangled states.

[0026]

[0032] In some embodiments, spatial multiplexing of several nondeterministic photon sources (also known as MUX photon sources) is used. Many different spatial multiplexing architectures are possible without departing from the scope of this disclosure. Temporal multiplexing can also be performed instead of or in combination with spatial multiplexing. Multiplexing schemes can be used that use logarithmic trees, general-purpose Mach-Zehnder interferometers, multimode interferometers, chain sources, dump-to-pump chain sources, asymmetric polycrystalline single-photon sources, or any other type of multiplexing architecture. In some embodiments, the photon sources can be used in multiplexing schemes that involve quantum feedback control, etc.

[0027] Resource state generator

[0033] The resource state generator 110 can receive photons and / or entangled photon states from the photon source module 105, convert them into one or more entangled photon states, and then output these entangled photon states to the output waveguide 120. The entangled photon states may include, but are not limited to, Bell states, GHZ states, or more generally, n-qubit Greenberger-Horn-Zeilinger (GHZ) states (also known as "n-GHZ states"), which are entangled quantum states of n qubits (multiple entangled states), or any other entangled photon states.

[0028]

[0034] In some embodiments, the output waveguide 120 can be coupled to downstream circuits that can use entangled states to perform quantum computations. For example, entangled states generated by a resource state generator 110 can be used as resources for a downstream quantum optical circuit (not shown).

[0029]

[0035] In some embodiments, since entanglement is also a nondeterministic process, the resource state generator may include one or more analyzers or mux to generate appropriate entanglement states when required by downstream systems. In one embodiment, a photon analyzer 145 can be used to verify that appropriate entanglement states have been generated, as will be described in more detail below. In some embodiments, the resource state generator 110 includes one or more controllers (which may include, for example, a field-programmable gate array (FPGA), an application-specific integrated circuit (ASICS), etc.) that determine whether each stage of the resource state generator 110 has been successful, perform the switching logic described above, and output reference signals to classical channels 130b and / or 130d to notify other components of whether the resource state generator 110 has been successful.

[0030] Classical computers and clocks

[0036] In some embodiments, the classical computer system 125 includes memory, one or more processors, a power supply, an input / output (I / O) subsystem, and a communication bus for interconnecting these components. The processors can execute modules, programs, and / or instructions stored in memory, thereby performing processing operations. As described above, the qubit entanglement subsystem 100 may include classical channels 130 (e.g., classical channels 130a to 130d) for interconnecting and providing classical information between components. In various embodiments, the classical computing system 125 can communicate with and / or control the photon source module 105 and / or the resource state generator 110 (e.g., via classical information channels 130a, 130b). Note that classical channels 130a to 130d do not all need to be the same. For example, classical channels 130a to 130d may include a bidirectional communication bus that carries one or more reference signals (e.g., one or more clock signals), one or more control signals, or any other signals that carry classical information (e.g., herald signals, photon detector readout signals, etc.).

[0031]

[0037] In some embodiments, a system clock signal can be provided to the photon source module 105 and the resource state generator 110 via an external source (not shown) or by a classical computer system 125 generated via classical channels 130a and / or 130b. In some embodiments, the system clock signal provided to the photon source module 105 triggers the photon source module 105 to attempt to output one photon per interconnect waveguide 115. In some embodiments, the system clock signal provided to the resource state generator 110 triggers or gates a set of detectors in the resource state generator 110 to attempt to detect a photon. For example, in some embodiments, triggering a set of detectors in the resource state generator 110 to attempt to detect a photon includes gates controlling the set of detectors.

[0032]

[0038] It should be noted that in some embodiments, the photon source module 105 and the resource state generator 110 may have internal clocks. For example, the photon source module 105 may have an internal clock generated and / or used by a controller, and the resource state generator 110 may have an internal clock generated and / or used by a separate controller. In some embodiments, the internal clocks of the photon source module 105 and / or the resource state generator 110 are synchronized to an external clock (e.g., a system clock provided by a classical computer system 125) (e.g., via a phase-locked loop). In some embodiments, either of the internal clocks may be used as a system clock itself (e.g., the internal clock of the photon source module 105 may be distributed to other components in the system and used as a master / system clock).

[0033]

[0039] Figure 2 shows a spatially multiplexed qubit entanglement subsystem 200 according to an embodiment of the present disclosure. As shown in Figure 2, the qubit entanglement subsystem 200 may be similar to the qubit entanglement subsystem 100, but the qubit entanglement subsystem 200 includes a photon source module 205 configured to generate photon pairs. For simplicity, only one interconnect waveguide 115 coupling the photon source module 205 to a resource state generator 110 is shown, and only one output waveguide 120 coupling the resource state generator to downstream circuits is shown. Further shown in detail within the photon source module 205 are a plurality of spatially multiplexed photon sources 215a...215n, each coupled to a multiplexer 235 and configured to allow the probability of transmitting a photon from the interconnect waveguide 115 during a given "trigger" signal 255 to approach 1.

[0034]

[0040] More specifically, in this embodiment, a plurality of nondeterministic photon sources 215a...215n are configured to each simultaneously attempt to generate photon pairs in response to a trigger signal 255. In some embodiments, the trigger signal 255 can be generated by a classical computer system 125, and in other embodiments, different systems can generate the trigger signal 255. Each photon source 215a...215n can nondeterministically generate photon pairs (each containing a signal photon and a herald photon), where one photon (e.g., a herald photon) signals the presence of the other photon in the pair (e.g., a signal photon). In some embodiments, the photon pairs are not entangled, while in other embodiments, they are entangled, and in one embodiment, the photon pairs are Bell state pairs. In another embodiment, each photon source 215a...215n can be configured to generate entangled states of two or more photons.

[0035]

[0041] Each generated photon pair is sent to its respective splitter 220a...220n, which separates the signal photon from the herald photon. The signal photon is sent to its respective photon detection switch 225a...225n, and the herald photon is sent to its respective photon detector 230a...230n. When a herald photon is detected by each detector 230, the detector generates a detection signal that can be transmitted to the classical computer system 125, causing each photon detection switch 225a...225n to be configured to route the signal photon from the pass-through port 237a...237n to the multiplexer 235. If the photon detectors 230a...230n do not detect a herald photon, each photon detection switch 225a...225n can couple the output of its respective splitter 220a...220n to its respective emission port 240a...240n. This same process is performed for each of the multiple photon sources 215a...215n each time the trigger signal 255 is transmitted.

[0036]

[0042] In some embodiments, the photon detectors 230a...230n can be implemented by coupling the waveguide to a single-photon detector that generates a classical signal (e.g., a digital logic signal) indicating that a photon has been detected by the detector. Any type of photodetector with sensitivity to single photons can be used. In some embodiments, the detection of a photon (e.g., at the output end of the waveguide) may indicate an occupied mode, and the absence of a detected photon may indicate an unoccupied mode.

[0037]

[0043] In some embodiments, a given trigger signal 255 generates only a single signal photon from multiple photon sources 215a...215n, and the multiplexer 235 directs the signal photon to the resource state generator 110 via multiple photon routing switches 247a...247n within the multiplexer 235. In other embodiments, a given trigger signal 255 generates two or more photon pairs from multiple photon sources 215a...215n, and two or more signal photons are sent to the multiplexer 235. In such cases, the resource state generator 110 requires only one photon, so there are "excess" photons, of which at least one can be sent to the photon analyzer 260. Any additional photons can be directed to emission ports 240a...240n. In some embodiments, sensing of generated photons in a given trigger signal, and guiding specific photons to a resource state generator 110, specific excess photons to an analyzer 260, and any additional photons to emission ports 240a...240n can be performed by a classical computer system 125.

[0038]

[0044] In response to the reception of a signal photon, the photon analyzer 260 determines one or more properties of the received signal photon. In some embodiments, one or more properties may include, but are not limited to, color, jitter, wavelength, spectral width, and dispersion or delay with respect to the trigger cycle that generated the received photon. Thus, those skilled in the art will recognize that the photon analyzer may include one or more photon detectors, optical filters, polarizers, birefringent elements, and any number of other suitable photon components. In embodiments where the photon source module 105 generates an entangled state, the photon analyzer 260 may analyze the entangled state to determine that the correct entangled state has been generated. In further embodiments, quantum tomography can be performed, which can be generally described as the ability to characterize the “unknown” states and dynamics of a quantum system through physical measurements. Quantum tomography is generally performed by generating and analyzing many identical copies of the same state. Different measurements can be performed on each identical copy, and the results can be used to estimate the state and dynamics of the quantum system. In one embodiment, quantum tomography can be used to determine the superposition coefficients of the wavefunction of an entangled state. Those skilled in the art who benefit from this disclosure will understand many other photon and entangled photon properties that can be determined.

[0039]

[0045] In some embodiments, the photon analyzer 260 can determine which photon sources 215a...215n produced the signal photon by receiving detection signals from detectors 230a...230n. In other embodiments, the photon analyzer 260 can determine which photon sources 215a...215n produced the signal photon by using other data, including identifying specific characteristics of the signal photon associated with a particular photon source. For example, a slight shift in the wavelength of each signal photon can be used to distinguish which photon sources 215a...215n produced a particular photon. In some embodiments, each photon source module 105 and each resource state generator 110 may include two or more photon analyzers 260 for analyzing photons produced by multiple generators.

[0040]

[0046] During the normal operation of the photon source module 205, many photons are generated by each photon source 215a...215n. This allows the photon analyzer 260 to collect data on the photons generated by each of the photon sources 215a...215n, indicating the performance of each photon source. In one embodiment, the photon analyzer 260 ranks each photon source 215a...215n according to one or more characteristics of the photons generated by each generator, and using the data, ranks the photon sources from highest quality to lowest quality. Using this data in the future, when two or more pairs of photons are generated by multiple photon sources 215a...215n, a classical computer system 125 can use the data generated by the photon analyzer 260 to route the highest quality signal photons to the resource state generator 110 and send one of the remaining signal photons to the photon analyzer 260, thereby continuously updating the performance index of each photon source 215a...215n.

[0041]

[0047] In a further embodiment, the photon analyzer 260 can detect "defective" photon sources 215a...215n by comparing one or more characteristics of each signal photon to a threshold. In response, the classical computer system 125 can transmit one or more signals to prevent signal photons generated by the defective photon source from being routed to the resource state generator 110. In a further embodiment, if a defective photon source is identified, the photon source module 105 can switch to a surplus photon source in place of the defective photon source.

[0042]

[0048] In some embodiments, it may be beneficial to reroute signal photons after they have been routed by the multiplexer 235. This feature allows for analysis of the effect of a photon routing bus 275 extending between the multiplexer 235 and the resource state generator 110, or allows photons generated by high-quality photon sources 215a...215n to be guided to a photon analyzer 260 for characterization. In some embodiments, photon reroute can be achieved by a crossover switch 265 positioned between the multiplexer 235 and the resource state generator 110 / photon analyzer 260. In various embodiments, the crossover switch 265 can be configured to reroute signal photons guided to the resource state generator 110 by the multiplexer 235 to the photon analyzer 260, and to reroute signal photons guided to the photon analyzer 260 by the multiplexer 235 to the resource state generator 110. These and other features are described in more detail below. The embodiments disclosed herein primarily relate to photon-based systems, but the embodiments can be used in any system that uses entangled states.

[0043]

[0049] Figure 3 shows a spatially multiplexed qubit entanglement subsystem 300 according to an embodiment of the present disclosure. As shown in Figure 3, the qubit entanglement subsystem 300 may be similar to the qubit entanglement subsystem 200 shown in Figure 2, but the qubit entanglement subsystem 300 includes three nondeterministic photon sources 215a...215c, with the paths of photon pairs generated by each respective generator shown for one trigger signal 255.

[0044]

[0050] The first and third photon sources 215a and 215c each produce first and third photon pairs 307a and 307c, respectively, in response to a specific trigger signal, while the second photon source 215b did not produce any photon pairs during this specific trigger signal. In this example, the first photon pair 307a produced by the first photon source 215a is represented by a circle, with the vertical line within the circle representing the signal photon 308a of the pair and the horizontal line representing the herald photon 309a of the pair. Similarly, the third photon pair 307c from the third photon source 215c is represented by a square, with the vertical line within the square representing the signal photon 308c of the pair and the horizontal line representing the herald photon 309c of the pair.

[0045]

[0051] As further shown in Figure 3, the first photon pair 307a is transmitted to a first splitter 220a that splits the first photon pair into a first signal photon 308a and a first herald photon 309a. The first herald photon 309a is transmitted to a first detector 230a, and the first detection signal 233a is transmitted to a first photon detection switch 225a. Accordingly, the first photon detection switch 225a routes the first signal photon 308a to a first photon routing switch 247a in the photon multiplexer 235. In some embodiments, the photon detection and routing signals can be processed by one or more internal classical computing resources, an external classical computer system 125, or a combination thereof.

[0046]

[0052] As described above, the second photon source 215b did not generate a photon pair during this particular trigger signal. The third photon pair 307c is transmitted to the third splitter 220c, which splits the third photon pair into a third signal photon 308c and a third herald photon 309c. The third herald photon 309c is transmitted to the third detector 230c, and the third detection signal 233c is transmitted to the third photon detector switch 225c. Accordingly, the third photon detector switch 225c routes the third signal photon 308c to the third photon routing switch 247c.

[0047]

[0053] A classical computer system 125 receives first and third detection signals 233a and 233c, respectively, and, based on the generation of first and third photon pairs 307a and 307c, respectively, changes the states of the first photon routing switch 247a and the third photon routing switch 247c in the multiplexer 235 to route the first signal photon 308a to the resource state generator 110 and the third signal photon 308c to the photon analyzer 260. However, in this embodiment, the classical computer system 125 connects a crossover switch 265 so that the first signal photon 308a, routed to the resource state generator 110 by the first photon routing switch 247a, is routed to the photon analyzer 260. Similarly, the third signal photon 308c, routed to the photon analyzer 260 by the third photon routing switch 247c, is then routed to the resource state generator 110. In some embodiments, the crossover switch 265 may be useful for determining any effect of the photon processing system bus 275 on photons passing through the bus. In further embodiments where a small number of high-quality photon sources may be available, photons generated by these high-quality photon sources may not be routed to the photon analyzer 260, or may be routed very little. Thus, the crossover switch 265 makes it possible to route photons from any photon source to the photon analyzer 260 to maintain continuous characterization of all photon pairs. Those skilled in the art who benefit from this disclosure will understand many other applications of the crossover switch 265.

[0048]

[0054] Figure 4 illustrates steps relating to Method 400, according to some embodiments of the present disclosure, for generating signal photons for a resource state generator and analyzing excess photons to characterize one or more photon sources. As shown in Figure 4, Method 400 begins with step 405, in which a trigger signal is generated by a qubit entanglement subsystem. The qubit entanglement subsystem can use one or more photon sources that nondeterminely generate photon pairs in response to a photon source receiving the trigger signal. As stated above, such embodiments are not limited to photon sources that generate photon pairs, and the photon sources can generate any combination of two or more unentangled or entangled states of photons.

[0049]

[0055] In step 410, in response to a trigger signal, the first photon source generates a first photon pair. The first photon pair may include a first signal photon and a first herald photon. In other embodiments, multiple pairs of photons or entangled photons can be generated.

[0050]

[0056] In step 415, in response to the trigger signal, the second photon source generates a second photon pair. The second photon pair may include a second signal photon and a second herald photon. In some other embodiments, multiple pairs of photons or entangled photons can be generated.

[0051]

[0057] In step 420, in the first pair of photons, the first signal photon is separated from the first herald photon. In one embodiment, the separation can be performed using a wavelength division splitter or other suitable device. The first signal photon can be transmitted from the first splitter port, and the first herald photon can be transmitted from the second splitter port.

[0052]

[0058] In step 425, in the second pair of photons, the second signal photon is separated from the second herald photon. In one embodiment, the separation can be performed using a wavelength division splitter or other suitable device. The second signal photon can be transmitted from the primary splitter port, and the first herald photon can be transmitted from the secondary splitter port.

[0053]

[0059] In step 430, the first herald photon can be detected using the first detector coupled to the second splitter port. In response to the detection of the first herald photon, the first detector can transmit a first detection signal.

[0054]

[0060] In step 435, a second herald photon can be detected using a second detector coupled to the secondary splitter port. In response to the detection of the second herald photon, the second detector can transmit a second detection signal.

[0055]

[0061] In step 440, the state of the first photon detection switch is changed to allow the first signal photon to pass through. In some embodiments, the state of the first photon detection switch changes in response to a first detection signal transmitted by the first detector.

[0056]

[0062] In step 445, the state of the second photon detection switch is changed to allow the second signal photon to pass through. In some embodiments, the state of the second photon detection switch changes in response to a second detection signal transmitted by the second detector.

[0057]

[0063] In step 450, the first photon routing switch is configured to route the first signal photon from the first photon detection switch to the resource state generator. In some embodiments, the first photon routing switch can be configured by a detection logic circuit or a classical computer system, as will be described in more detail herein.

[0058]

[0064] In step 455, the second photon routing switch is configured to route the second signal photon from the second photon detection switch to the photon analyzer. In some embodiments, the second photon routing switch can be configured by a detection logic circuit or a classical computer system, as will be described in more detail below.

[0059]

[0065] In some embodiments, the detection logic circuit receives first and second detection signals and configures first and second photon routing switches so that a single source photon is transmitted to the resource state generator in response to each trigger signal. In embodiments where only one detection signal is received, the detection logic circuit configures the corresponding photon routing switch to transmit a signal photon to the resource state generator. In embodiments where two or more detection signals are received, the detection logic circuit configures one photon routing switch to transmit a corresponding signal photon to the resource state generator and a separate signal photon to the photon analyzer. In further embodiments, as will be described in more detail herein, the detection logic circuit can work in conjunction with data acquired by the photon analyzer to select the highest quality photon and transmit it to the resource state generator.

[0060]

[0066] In step 460, the second signal photon is received by the photon analyzer.

[0061]

[0067] In step 465, in response to the reception of the second signal photon, the photon analyzer determines one or more properties of the second signal photon. In some embodiments, one or more properties may include, but are not limited to, color, jitter, wavelength, spectral width, and dispersion or delay with respect to the clock cycle that produced the received photon. Those skilled in the art who benefit from this disclosure will understand many other properties that can be determined. In some embodiments, the photon analyzer can determine which photon source produced the signal photon by receiving a detection signal from a detector. In other embodiments, the photon analyzer can determine which photon source produced the signal photon using other data, which includes identifying specific properties of the signal photon associated with a particular photon source. For example, a slight shift in the wavelength of each signal photon can be used to distinguish which photon source produced a particular photon, and that data can be used to determine the properties of each photon source. In embodiments in which the photon sources produce entangled states of two or more photons, the photon analyzer can perform quantum tomography on the entangled states.

[0062]

[0068] It should be understood that Method 400 is illustrative and is subject to modification and alteration. Steps described as sequential may be performed in parallel, the order of steps may be changed, and steps may be modified, combined, added, or omitted. Although Method 400 was described and illustrated using two photon sources, any number of photon sources and any physical layout can be used.

[0063]

[0069] Figure 5 illustrates steps related to a method 500 for generating and controlling the quality of signal photons in a resource state generator, according to some embodiments of the present disclosure. As shown in Figure 5, in method 500, step 505 begins with receiving a trigger signal from one or more photon sources. In some embodiments, the photon processing system can benefit from a photon source that deterministically generates a single signal photon in response to supplying a trigger signal to the photon source.

[0064]

[0070] In step 510, in response to a trigger signal, multiple photon sources generate multiple photon pairs. Each photon pair may include a signal photon and a herald photon. In other embodiments, multiple pairs can be generated, and in further embodiments, a photon entanglement state can be generated.

[0065]

[0071] In step 515, for each generated photon pair, the signal photon is separated from the herald photon. In one embodiment, the separation can be performed using a wavelength division splitter or other suitable device.

[0066]

[0072] In step 520, each herald photon of the generated photon pair can be detected by its respective detector. In response to the detection of a herald photon, each detector can transmit its respective detection signal. In some embodiments, a detection logic circuit can receive one or more detection signals, and in other embodiments, a classical computer system can receive one or more detection signals.

[0067]

[0073] In step 525, it is determined whether two or more herald photons have been detected. In some embodiments, a detection logic circuit can make this determination. If only one herald photon is detected, there is only one signal photon, and the detection logic circuit proceeds to step 530 to have the signal photon sent to the resource state generator. If two or more herald photons are detected, there are two or more generated signal photons, and the process proceeds to step 535. In step 535, the detection logic circuit can work with a photon analyzer to determine which signal photon has the highest quality based on previously characterized photons from each photon source. In step 540, the photon routing switch is configured to route the highest quality photon to the resource state generator, and the second signal photon is routed to the photon analyzer. In this way, only the highest quality signal photon is sent to the resource state generator.

[0068]

[0074] Method 500 is illustrative and should be understood to be modifiable and adaptable. Steps described as sequential may be performed in parallel, the order of steps may be changed, and steps may be modified, combined, added, or omitted.

[0069]

[0075] Figure 6 shows a time-multiplexed qubit entanglement subsystem 600 according to an embodiment of the present disclosure. As shown in Figure 6, the qubit entanglement subsystem 600 may be similar to the spatially multiplexed qubit entanglement subsystem 300 (shown in Figure 3), but the time-multiplexed qubit entanglement subsystem 600 includes two time-multiplexed nondeterministic photon sources 215a...215c, which can direct the generated photons to a resource state generator via a variable delay 620, as will be described in more detail below.

[0070]

[0076] In the entangled subsystem 600 of Figure 6, the classical computer system 125 includes a master clock 605 that controls the operation of photon sources 215a and 215b and the resource state generator 110. More specifically, in this exemplary embodiment, the resource state generator 110 requires photons from the photon source module 610 for each clock cycle, which is represented by the resource state generator trigger 615, denoted as "1X". In comparison, the classical computer system 125 sends four trigger signals 255, denoted as "4X", to the photon sources 215a and 215b for each resource state generator trigger 615. That is, the photon sources 215a and 215b are triggered four times as often as the resource state generator. This 4:1 ratio allows for the use of fewer photon sources without losing photon generation opportunities. In other words, all resource state generator clock cycles are supplied by the two photon sources, each operating four times for a total of eight photon generation cycles. In comparison, a spatially multiplexed design requires eight photon sources to have eight photon generation cycles per resource state generator clock cycle. Thus, the nondeterminism of the photon sources can be overcome by spatial and / or temporal multiplexing of the photon sources. Those skilled in the art who benefit from this disclosure will understand many other configurations of temporally multiplexed photon sources, including one photon source that can operate many times (e.g., 2X, 4X, 10X, 100X, 1000X) for any other combination and cycle ratio of all resource state generator clock cycles and photon sources.

[0071]

[0077] As further shown in Figure 6, the multiplexer 235 is coupled to a classical computer system 125 that tracks when photons are generated and, accordingly, directs them to a resource state generator 110 and / or a photon analyzer 260. In a time-multiplexed system, an additional variable delay 620 can be placed between the multiplexer 235 and the resource state generator, but in other embodiments, other system architectures can be used to accommodate a four-to-one ratio. In this particular example, on a first trigger signal 255 sent to the photon source, a photon is generated and is not needed by the resource state generator 110 until a fourth clock cycle, so that the photon can be held in a "3-cycle" bin in the variable delay 620. This delays the transmission of the photon to the resource state generator 110 for the next three clock cycles, until the fourth clock cycle. If a second photon is generated during the first cycle, the classical computer system 125 can direct that photon through the multiplexer 235 to the photon analyzer 260. At this point, since there are already photons waiting for the resource state generator 110, all further photons generated in subsequent clock cycles can be sent to the photon analyzer 260.

[0072]

[0078] The operation of the variable delay 620 is the same even if no photons were generated in the first cycle, but one photon was generated in the second cycle. The classical computer system 125 directs the photon to the "2-cycle" bin, delays the photon for the next two cycles until the fourth cycle, and then emits it to the resource state generator 110. Any other photons generated can be considered "excess" and sent to the photon analyzer 260. A similar operation is performed if one or more photons are generated only in the third and / or fourth cycles. Those skilled in the art will benefit from this disclosure and recognize many variations, modifications, and alternatives for delaying and transferring generated photons in time-multiplexed photon source architectures. As described herein, the photon sources 215a, 215b can generate any type or combination of unentangled or entangled photons, including one, two, or more photons.

[0073]

[0079] Figure 7 is a simplified block diagram of an example of a linear optical quantum computer (LOQC) 700 that, according to a particular embodiment, can use the spatially and / or temporally multiplexed photon sources disclosed herein. The LOQC 700 may include a plurality of photon sources 715 in a photon source module 705, a linear optical quantum computing circuit acting as a resource state generator 710, a reconfigurable single-photon detection circuit 720, and a classical computer 730. Each photon source 715 may be configured to deterministically (or nearly deterministically) generate a sequence of photons that can be used as qubits. In some embodiments, the photon sources 715 may include cascaded (or multiplexed) photon sources, for example, based on spontaneous four-wave mixing (SFWM) or spontaneous parametric downconversion (SPDC) in a passive nonlinear optical medium. In each photon source 715, photons can be nondeterministically produced in pairs (signal photon and herald photon), where one photon (e.g., herald photon) signals the presence of the other photon in the pair (e.g., signal). Therefore, if a herald photon is detected in a photon source, the corresponding signal photon can be used as the output of the photon source, and other photon sources of the cascaded (or multiplexed) photon source can be sent to the photon analyzer 740. However, in other embodiments, the photon source 715 can be used to generate any amount of photons and / or types of unentangled photons or entangled photon states, as will be described in more detail herein.

[0074]

[0080] The photon analyzer 740 can determine one or more properties of each received “excess” photon and / or photon entanglement state generated from the photon source module 705. In some embodiments, one or more properties may include, but are not limited to, color, jitter, wavelength, spectral width, and dispersion or delay with respect to the clock cycle that generated the received photon. In other embodiments where the photon source generates two or more photon entanglement states, the photon analyzer 740 can perform quantum tomography on the excess entanglement states. Those skilled in the art who benefit from this disclosure will understand many other properties of photons and / or photon sources that can be determined by the photon analyzer 740. In some embodiments, the photon analyzer can determine which photon source generated the photons and / or photon entanglement states by receiving detection signals from associated detectors. In other embodiments, the photon analyzer may use other data to determine which photon source generated the photons and / or entangled photons, including identifying specific characteristics of the photons and / or entangled photons associated with a particular photon source. For example, a slight shift in the wavelength of each signal photon can be used to determine which photon source generated a particular photon.

[0075]

[0081] In some embodiments, the photon analyzer 740 can be used to optimize the performance of each photon source 715 by selecting photons from the highest quality photon source and routing "excess" photons to the photon analyzer or termination port. In further embodiments, the photon analyzer 740 can determine whether the photon source has generated a suitable photon entanglement state by performing quantum tomography.

[0076]

[0082] The resource state generator 710 may include a waveguide, a beam splitter, a phase shifter, a delay line, and a network of other photon components and circuits. The photon components and circuits may be used to implement optically controlled NOT (CNOT) gates to generate bell states, or to implement fusion gates to generate larger entangled states that can be stored in the delay line.

[0077]

[0083] The cluster analyzer 745 can be used to perform an analysis of excess entanglement states of photons generated by the resource state generator 710. More specifically, in one embodiment, the cluster analyzer 745 can analyze the entanglement states of two or more photons to determine that the correct entanglement state has been generated. In a further embodiment, quantum tomography can be performed by generating and analyzing many identical copies of the same state. Different measurements can be performed on each identical copy, and the results can be used to estimate the state and dynamics of the quantum system. In one embodiment, quantum tomography can be used to determine the superposition coefficients of the wave functions of the entangled state.

[0078]

[0084] The reconfigurable single-photon measurement circuit 720 may include multiple single-photon detectors configured to measure entangled single photons (qubits) based on some measurement pattern, sometimes called a measurement mask.

[0079]

[0085] The classical computer 730 can decode the photon results measured by the single-photon measurement circuit 720 and perform some logic processing to generate computational results. In some embodiments, the classical computer 730 can feed back the decoded results to the single-photon measurement circuit 720. For example, based on the decoded results, the classical computer 730 can adjust some measurement masks or determine some measurement masks that have not been predetermined for use by the single-photon measurement circuit 720.

[0080]

[0086] A linear optical quantum computer (LOQC) 700 can include millions of optical components such as couplers, resonators, single-photon detectors, beam splitters, interferometers, switches, phase shifters, and delay lines. According to certain embodiments, these optical components can be manufactured as photonic integrated circuits (PICs) on a semiconductor wafer, such as silicon photon integrated circuits on a silicon wafer, using semiconductor process technology. 7

[0081]

[0087] The Linear Optical Quantum Computer (LOQC) 700 may also include numerous electronic integrated circuits (EICs), such as control logic and switches for a Herald single-photon source. To achieve high performance (e.g., high speed), it may be necessary to minimize the interconnections between the electronic circuits and the photon integrated circuits. Furthermore, many components of the LOQC 700 may need to operate at extremely low temperatures, such as below 140K or below 5K, to achieve the desired performance.

[0082]

[0088] In some embodiments, a qubit, typically described herein as a photon, can be a collection of quantum systems and / or particles, which can be formed using any qubit architecture. For example, a quantum system can be a particle such as an atom, ion, nucleus, and / or photon. In other examples, a quantum system can be another designed quantum system, such as a flux qubit, a phase qubit, or a charge qubit (e.g., formed from a superconducting Josephson junction), a topological qubit (e.g., a Majorana fermions), or a spin qubit formed from a vacancy center (e.g., a nitrogen vacancy in diamond). Furthermore, for clarity of explanation, the term “qubit” is used herein, but a system can also use quantum information carriers that encode information in a way that is not necessarily associated with binary bits. For example, according to some embodiments, a qubit (i.e., a quantum system capable of encoding information in three or more quantum states) can be used.

[0083]

[0089] It will be apparent to those skilled in the art that substantial modifications can be made according to specific embodiments. For example, customized hardware may be used, and / or certain elements may be implemented in hardware, software (including portable software such as applets), or both. Furthermore, connections to other computing devices, such as network input / output devices, can be employed.

[0084]

[0090] Referring to the attached drawings, components that may include memory may also include non-temporary machine-readable media. As used herein, the terms “machine-readable media” and “computer-readable media” refer to any storage medium involved in providing data that causes a machine to operate in a particular way. In the embodiments provided above, various machine-readable media may be involved in providing instructions / code to a processor and / or other devices for execution. Additionally or alternatively, machine-readable media may be used to store and / or carry such instructions / code. In many implementations, computer-readable media are physical and / or tangible storage media. Such media can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Common forms of computer-readable media include, for example, magnetic and / or optical media, punch cards, paper tape, any other physical media having a pattern of holes, RAM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), FLASH-EPROM, any other memory chip or cartridge, carrier waves as described below, or any other medium from which a computer can read instructions and / or code.

[0085]

[0091] The methods, systems, and devices described herein are examples. Various embodiments may omit, substitute, or add various procedures or components as needed. For example, features described in relation to a particular embodiment can be combined in various other embodiments. Different aspects and elements of embodiments can be combined in similar ways. Various components of the figures provided herein can be implemented in hardware and / or software. Furthermore, technology is evolving, and therefore many elements are examples that do not limit the scope of this disclosure to those specific examples.

[0086]

[0092] Referencing signals such as bits, information, values, elements, symbols, characters, variables, terms, numbers, and digits has sometimes proven convenient, primarily for reasons of general use. However, it should be understood that all of these or similar terms should be associated with appropriate physical quantities and are merely convenient labels. Unless otherwise specified, as is evident from the above descriptions, throughout this specification, descriptions using terms such as “processing,” “computing,” “calculating,” “determining,” “ascertaining,” “identifying,” “associating,” “measuring,” and “performing” are understood to refer to the operation or processing of a particular device, such as a dedicated computer or similar dedicated electronic computing device. Thus, in the context of this specification, a dedicated computer or similar dedicated electronic computing device can manipulate or convert signals that are typically represented as physical electronic, electric, or magnetic quantities within the memory, registers, or other information storage devices, transmitting devices, or display devices of the dedicated computer or similar dedicated electronic computing device.

[0087]

[0093] Those skilled in the art will understand that the information and signals used to communicate the messages described herein can be represented using any of a variety of different techniques and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0088]

[0094] As used herein, the terms “and,” “or,” and “and / or” may have a variety of meanings, which are also expected to depend at least in part on the context in which such terms are used. Typically, when “or” is used to relate a list such as A, B, or C, it is intended to mean A, B, and C, used here in an inclusive sense, and similarly, it is intended to mean A, B, or C, used here in an exclusive sense. Furthermore, as used herein, the term “one or more” may be used to describe any singular feature, structure, or property, or to describe several combinations of features, structures, or properties. However, it should be noted that this is merely illustrative, and the claimed subject matter is not limited to these examples. Furthermore, when the term “at least one of” is used to relate a list such as A, B, or C, it may be interpreted to mean any combination of A, B, and / or C, such as A, B, C, AB, AC, BC, AA, AAB, ABC, AABBCCC, etc.

[0089]

[0095] Throughout this specification, references to “one example,” “an example,” “certain examples,” or “exemplary implementation” mean that any particular feature, structure, or characteristic described in relation to a feature and / or example may be included in at least one feature and / or example of the claimed subject matter. Therefore, occurrences of phrases such as “in one example,” “an example,” “in certain examples,” “in certain implementations,” or other similar phrases in various parts of this specification do not necessarily all refer to the same feature, example, and / or limitation. Furthermore, any particular feature, structure, or characteristic may be combined in one or more examples and / or features.

[0090]

[0096] In some implementations, operation or processing may involve the physical manipulation of physical quantities. Typically, but not always, such quantities may take the form of electrical or magnetic signals that can be stored, transferred, combined, compared, or otherwise manipulated. Referring to signals as bits, data, values, elements, symbols, characters, terms, digits, etc., has sometimes proven convenient, primarily for reasons of general use. However, it should be understood that all these or similar terms should be associated with appropriate physical quantities and are merely convenient labels. Unless otherwise specified, as is evident from the descriptions herein, any use of terms such as “processing,” “computing,” “calculating,” and “determining” throughout this specification is understood to refer to the operation or processing of a specific device, such as a dedicated computer, dedicated computing device, or similar dedicated electronic computing device. Therefore, in the context of this specification, a dedicated computer or similar dedicated electronic computing device can manipulate or convert signals that are typically represented as physical electronic or magnetic quantities in the memory, registers, or other information storage devices, transmitting devices, or display devices of the dedicated computer or similar dedicated electronic computing device.

[0091]

[0097] The detailed description above includes numerous specific details to provide a complete understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter can be implemented without these specific details. In other examples, methods and apparatus known to those skilled in the art are not described in detail so as not to obscure the claimed subject matter. Therefore, the claimed subject matter is not limited to the specific examples disclosed, and such claimed subject matter is also intended to include all embodiments and their equivalents that fall within the scope of the attached claims.

[0092]

[0098] In embodiments including firmware and / or software, the methodology may be implemented in modules (e.g., procedures, functions, etc.) that perform the functions described herein. When implementing the methodology described herein, any machine-readable medium that materializes the instructions may be used. For example, software code may be stored in memory and executed by a processor unit. Memory may be implemented within or outside the processor unit. As used herein, the term “memory” means any type of long-term, short-term, volatile, non-volatile, or other memory, and is not limited to any particular type of memory or number of memories, or the type of medium in which the memory is stored.

[0093]

[0099] When implemented in firmware and / or software, the functionality may be stored as one or more instructions or codes on a computer-readable storage medium. Examples include computer-readable media encoded in data structures and computer-readable media encoded in computer programs. Computer-readable media include physical computer storage media. Storage media can be any available medium that can be accessed by a computer. Such computer-readable media may include RAM, ROM, EEPROM, compact disk read-only memory (CD-ROM) or other optical disk storage devices, magnetic disk storage devices, semiconductor storage devices, or other storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. As used herein, disks and discs include compact disks (CDs), laser disks, optical disks, digital multipurpose disks (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while discs reproduce data optically using a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0094]

[0100] In addition to storage on a computer-readable storage medium, instructions and / or data may be provided as signals on a transmission medium included in a communication device. For example, the communication device may include a transceiver having signals indicating instructions and data. The instructions and data are configured to cause one or more processors to perform the functions outlined in the claims. That is, the communication device includes a transmission medium having signals indicating information for performing the disclosed functions. At a first time point, the transmission medium included in the communication device may include a first portion of the information for performing the disclosed functions, and at a second time point, the transmission medium included in the communication device may include a second portion of the information for performing the disclosed functions.

Claims

1. A quantum computing system, Photon processing system and, Photon analyzer and, A photon source module coupled to the photon processing system and the photon analyzer, A photon source configured to emit one or more photons in response to a trigger signal, A photon multiplexer configured to guide the emitted one or more photons to the photon processing system or the photon analyzer, A photon source module, A quantum computing system equipped with [the necessary components].

2. The quantum computing system according to claim 1, wherein the photon multiplexer guides the emitted one or more photons to the photon processing system when the photon source module emits one photon for each trigger signal.

3. The quantum computing system according to claim 1, wherein the photon multiplexer guides one of the one or more photons emitted to the photon analyzer when the photon source module emits two or more photons for each trigger signal.

4. The quantum computing system according to claim 1, wherein the photon processing system is a resource state generator.

5. The quantum computing system according to claim 1, wherein the one or more photons are entangled photons.

6. The quantum computing system according to claim 1, wherein the at least one photon source is a plurality of spatially multiplexed photon sources.

7. The quantum computing system according to claim 1, wherein the at least one photon source is a plurality of temporally multiplexed photon sources.

8. A first photon source configured to generate a first pair of photons, wherein each first pair of photons includes a first signal photon and a first herald photon, A second photon source configured to generate a second pair of photons, wherein each second pair of photons includes a second signal photon and a second herald photon, A first detector configured to generate a first detection signal in response to the detection of the first herald photon, A second detector configured to generate a second detection signal in response to the detection of the second herald photon, A detection logic circuit configured to guide one of the first signal photon or the second signal photon to a photon analyzer and the other of the first signal photon or the second signal photon to a photon processing system in response to a detection logic circuit that receives the first detection signal and the second detection signal, A device equipped with the following features.

9. The device according to claim 8, further comprising a multiplexer that, in response to receiving one or more signals from the detection logic circuit, routes one of the first signal photons or the second signal photons to the photon analyzer and routes the one of the first signal photons or the second signal photons to the photon processing system.

10. The device according to claim 8, wherein the detection logic circuit guides the first signal photon and the second signal photon based on the respective quality levels of the first signal photon and the second signal photon.

11. The device according to claim 8, wherein, in response to the reception of the first signal photon or the second signal photon, the photon analyzer determines the characteristics of one or more of the received signal photons.

12. The device according to claim 11, wherein the one or more characteristics include color, jitter, wavelength, spectral width, or dispersion.

13. The device according to claim 8, wherein during the repeated operation of the first photon source and the second photon source, the photon analyzer determines one or more characteristics of first signal photons generated by the first photon source and one or more characteristics of second signal photons generated by the second photon source.

14. The device according to claim 13, wherein the photon analyzer compares the characteristics of one or more of the first signal photons with the characteristics of one or more of the second signal photons.

15. The device according to claim 14, wherein, in response to the comparison, the photon analyzer transmits a command to the photon processing system to receive more first signal photons than second signal photons.

16. The device according to claim 9, further comprising a crossover switch for redirecting signal photons routed to the photon analyzer by the multiplexer to the photon processing system.

17. A step of generating a first photon pair using a first photon source, wherein the first photon pair includes a first signal photon and a first herald photon, A step of generating a second photon pair using a second photon source, wherein the second photon pair includes a second signal photon and a second herald photon, The steps include generating a first detection signal in response to the detection of the first herald photon, A step of generating a second detection signal in response to the detection of the second herald photon, The steps include: routing one of the first signal photon or the second signal photon to a photon analyzer and routing the other of the first signal photon or the second signal photon to a photon processing system in response to a detection logic circuit that receives the first detection signal and the second detection signal; A method for generating photons, comprising the following features.

18. The method according to claim 17, wherein the routing is performed by a multiplexer controlled by the detection logic circuit.

19. The method according to claim 18, wherein the detection logic circuit instructs the multiplexer to route the first signal photon and the second signal photon based on the respective quality levels of the first signal photon and the second signal photon.

20. The method according to claim 17, wherein, in response to the reception of the first signal photon or the second signal photon, the photon analyzer determines the characteristics of one or more of the received signal photons.

21. The method according to claim 20, wherein the one or more characteristics include color, jitter, wavelength, spectral width, or dispersion.

22. The method according to claim 21, wherein during the repeated operation of the first photon source and the second photon source, the photon analyzer determines one or more characteristics of the first signal photon and one or more characteristics of the second signal photon.

23. The method according to claim 22, wherein, in response to the determination of one or more characteristics of the first signal photon and the second signal photon, the photon analyzer transmits a command to the photon processing system to cause it to receive more first signal photons than second signal photons.

24. A plurality of photon sources, each configured to non-deterministically generate a photon pair in response to the reception of a trigger signal, wherein each photon pair includes a signal photon and a herald photon, A plurality of photon detectors, each coupled to the respective photon source of the plurality of photon sources, are configured to generate a detection signal when they detect the herald photon of each generated photon pair, A plurality of photon routing switches, each coupled to its own photon source and configured to direct its respective signal photon to a photon processing system or photon analyzer, A photon detection logic circuit is configured to receive each detection signal, and in response to receiving two or more detection signals for each trigger signal, transmit control signals to the plurality of photon routing switches to route one signal photon to the photon analyzer and one signal photon to the photon processing system, A photon source equipped with this feature.

25. The photon source according to claim 24, wherein the photon analyzer determines one or more characteristics of the signal photon in response to the reception of the signal photon.

26. The photon source according to claim 25, wherein, after receiving a plurality of trigger signals, the photon analyzer determines the characteristics of one or more signal photons generated by each of the plurality of photon sources and ranks the quality of each of the photon sources.

27. The photon source according to claim 26, wherein, in response to receiving two or more detection signals for each trigger signal, the photon analyzer transmits one or more signals to route signal photons from the highest quality photon source to the photon processing system.

Images