DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Claim Rejections - 35 USC § 112 – Scope of Enablement
The following is a quotation of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), first paragraph:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-17 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, because the specification, while being enabling for a limited scope based on the teachings in the application, does not reasonably provide enablement for the full scope recited in the claims. The specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the invention commensurate in scope with these claims.
MPEP 2164.08 states: “The Federal Circuit has repeatedly held that ‘the specification must teach those skilled in the art how to make and use the full scope of the claimed invention without ‘undue experimentation’.” In re Wright, 999 F.2d 1557, 1561, 27 USPQ2d 1510, 1513 (Fed. Cir. 1993).
Scope of the Claims and Teachings of the Application.
Claim 1 recites
A quantum communications device element comprising:
a receiver configured to:
receive a quantum input signal in a statistical mixture comprising a pre- determined set of quantum states;
probabilistically determine the quantum states of the predetermined set of quantum states of the quantum input signal; and
output input signals corresponding to the quantum states of the quantum input signal;
a coupling device coupled to the receiver, said coupling device being configured to convert the input signals to an output signal by time-division multiplexing the input signals; and
a detector coupled to the coupling device, the detector being configured to receive the output signal wherein the coupling device is a waveguide device comprising a plurality of input waveguides in communication with an output waveguide, and a transition region along which the waveguide changes from the plurality of input waveguides to the output waveguide, wherein the transition region is configured to couple the input signals with the output signal.
This broadly recites a receiver, a coupling device, and a detector, each “configured to” perform functionality without requiring particular structure for the functionality. As a result, the claim has a broad scope that includes a broad range of structures (or perhaps any structure) for each element to perform the desired functionality. The application, in contrast, appears to teach the use of particular structure for each of the receiver, coupling device, and detector. See, for example, FIG. 1 of the application.
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[0033] FIG. 1 is a schematic view of a quantum communications device element 100 suitable for facilitating a quantum communications protocol. In the present example, the quantum communications device element 100 is suitable for use with the known Bennett-Brassard 1984 (BB84) protocol.
[0034] The quantum communications device element 100 comprises a receiver 102; a coupling device 104; and a detector 106. The receiver 102 is in communication with the coupling device 104. In the present example, the receiver 102 is in optical communication with the coupling device 104. The detector 106 is also in communication with the coupling device 104. In the present example, the detector 106 is in optical communication with the coupling device 104.
In other words, it illustrates the receiver 102, the coupling device 104, and the detector 106. Each of the receiver, the coupling device, and the detector will be discussed in turn.
The Receiver.
Claim 1 recites a receiver “configured to” perform functionality without requiring any particular structure for the receiver. FIG. 1 (reproduced above) illustrates the receiver 102 including optical receiving means 103 and state discriminators 105. See:
[0035] The receiver 102 comprises: an optical receiving means 103; and a state discrimination device 105. In the present example, the optical receiving means 103 is an optical fibre.
More specifically, the application teaches the use of particular state discriminators arranged in a particular manner. See the particular arrangement of different state discriminators 105 illustrated in FIG. 1. See also:
[0045] The state discrimination device 105 according to the present example comprises a 50:50 beam-splitter 105A; a first polarizing beam-splitter 105B; a second polarizing beam-splitter 105C; a half-wave plate 105D. The state discrimination device 105 is in optical communication with the first optical fibre 108; the second optical fibre 110; the third optical fibre 112; and the fourth optical fibre 114.
[0046] The state discrimination device 105 is arranged such that an incoming photon passes through the 50:50 beam-splitter 105A. If the photon is reflected by the 50:50 beam-splitter 105A, the first polarizing beam-splitter 105B directs the photon to the first optical fibre 108 or the second optical fibre 110 depending on the polarization of the photon. If the photon is transmitted by the 50:50 beam-splitter 105A, the photon passes through the half-wave plate 105D and the second polarizing beam-splitter 105C directs the photon to the third optical fibre 112 or the fourth optical fibre 114.
[0047] For example, if the incoming photon is a vertically polarized photon reflected by the 50:50 beam-splitter 105A, the photon is received by the first optical fibre 108. If the incoming photon is a vertically polarized photon transmitted by the 50:50 beam-splitter 105A, the photon is received by the third optical fibre 112 or the fourth optical fibre 114 with equal probability.
In other words, the application teaches the use of particular state discriminators in a particular arrangement. The claim does not require any of these elements or any particular arrangement particular arrangement for the receiver. As a result, the claim has a scope the includes a receiver that can include any structure to perform the recited functionality, including structures without any state discriminators, or with state discriminators in fundamentally different arrangements than those taught in the application, or other structures. The application does not appear to teach how to make and use the full scope of the claim.
The Coupling Device.
Claim 1 recites a coupling device “configured to” perform functionality without requiring any particular structure. FIG. 1 illustrates the coupling device 104 as a blank box, but FIG. 2 illustrates the particular structure of the coupling device 104.
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In particular, there are input waveguides on the left side, a transition region 116, and a single output waveguide 118. See:
[0036] The coupling device 104 is depicted in FIG. 2. The coupling device 104 is a waveguide device comprising a plurality of input waveguides; a transition region 116; and an output waveguide 118.
[0037] In the present example, the plurality of input waveguides consist of a first optical fibre 108; a second optical fibre 110; a third optical fibre 112; and a fourth optical fibre 114. The skilled person will appreciate that the plurality of input waveguides must comprise at least as many input waveguides as detectors required for the target quantum communications protocol using known techniques. In the present example, the BB84 protocol requires four detectors using known techniques.
In particular, the optical fibers 108-114 are SMF cores and the output 118 is MMF core. See:
[0038] The optical fibres 108, 110, 112, 114 comprise single-mode cores, each having a respective core diameter. In the present example, the core diameter of each single-mode core is 5 μm.
[0039] In the present example, the output waveguide 118 is an output optical fibre 118. The output optical fibre 118 comprises a multi-mode core having a core diameter. The core diameter of the multi-mode core is greater than the core diameter of each of the single-mode cores. In the present example, the core diameter of the multi-mode core is 10 μm.
The application also teaches that, under certain conditions, the input fibers can be MMF. In particular, the input fibers can be MMF if they support fewer modes than the output fiber. See:
[0040] The skilled person will appreciate that the optical fibres 108, 110, 112, 114 may also comprise multi-mode cores, as long as the multi-mode cores support fewer modes than the multi-mode core of the output optical fibre 118. In this example, a sum of the core diameters of each multi-mode optical fibre core is less than a core diameter of the multi-mode core.
The application also teaches that transition region of the coupling device is fused to form a unified body. See:
[0041] The transition region 118 is a region in which the optical fibres 108, 110, 112, 114 transition to the output optical fibre 118. In particular, the coupling device 104 changes smoothly from the optical fibres 108, 110, 112, 114 to the output optical fibre 118. In this way, light propagating along the coupling device 104 will follow the transition and the input signal is adiabatically coupled to the output signal.
[0042] To achieve the transition, the optical fibres 108, 110, 112, 114 are fused together to form a unified body, and a cross sectional scale of the unified body is reduced to form the output optical fibre 118.
The claim does not require any of these elements or their particular arrangement and structure for the coupling device. As a result, the claim has a scope the includes a coupling device that can include any structure to perform the recited functionality. The application does not appear to teach how to make and use the full scope of the claim.
The Detector.
Claim 1 also recites a detector “configured to” perform functionality without requiring any particular structure. The application teaches that this is a single-photon detector, specifically a single-photon avalanche detector. See:
[0043] In the present example, the detector 106 is a single-photon detector 106. In particular, the detector 106 is a single-photon avalanche diode 106.
The claim does not limit the detector to a single-photon avalanche detector or to a single-photon detector. The claim has a broad scope so that the detector can be any structure to perform the recited functionality in combination with the other claim elements. The application does not appear to teach how to make and use the full scope of the claim.
Method Claim 15.
Claim 15 recites:
A method for routing a plurality of signals to a detector, the method comprising:
receiving, at a receiver, a quantum input signal; probabilistically determining, by a state discrimination device element of the receiver, the quantum states of the quantum input signal;
outputting, by the receiver, input signals corresponding to the quantum states of the quantum input signal; converting, using a coupling device coupled to the receiver, the input signals to an output signal by time-division multiplexing the input signals; and
receiving, at a detector coupled to the coupling device, the output signal from the coupling device.
Claim 15 is a method corresponding to the operation of the apparatus of claim 1. Claim 15 broadly recites desired results without requiring the steps of operation taught in the application (e.g., without reciting the particular structure or the steps of operation of the structures taught in the application). In other words, claim 15 has a broad scope that recites desired results without being limited to particular steps of structures, similar to claim 1. The application does not appear to teach how to make and use the full scope of the claim.
The Dependent Claims.
The dependent claims add additional limitations but fail to address the issues raised with regard to the independent claims. The application does not appear to teach how to make and use the full scope of the dependent claims.
The Claims do not Recite the Particular Structure, Materials, or Steps.
As discussed above, the application teaches to make and use the invention using particular structure, materials, and steps to implement functionality of the claims. As also discussed above, the claims recite the desired functionality/results, but do not recite the particular structure, materials, or steps that accomplish the claimed functionality/results. This results in claims having a scope that is much broader than the teachings of the application.
When considering the teachings of the application and the scope of the claims, as discussed above, see MPEP 2173.05(g), 4th paragraph:
… Further, without reciting the particular structure, materials or steps that accomplish the function or achieve the result, all means or methods of resolving the problem may be encompassed by the claim. Ariad Pharmaceuticals., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1353, 94 USPQ2d 1161, 1173 (Fed. Cir. 2010) (en banc). Unlimited functional claim limitations that extend to all means or methods of resolving a problem may not be adequately supported by the written description or may not be commensurate in scope with the enabling disclosure, both of which are required by 35 U.S.C. 112(a) and pre-AIA 35 U.S.C. 112, first paragraph. In re Hyatt, 708 F.2d 712, 714, 218 USPQ 195, 197 (Fed. Cir. 1983); Ariad, 598 F.3d at 1340, 94 USPQ2d at 1167. …
This supports a finding that the broad scope of the claims is not be commensurate with the teachings in the disclosure.
No Teaching of a General Case for the Full Scope of the Claims.
The Examiner also notes that there is no teaching of an apparatus or method with the broad scope recited in the claims. If such a general case were contemplated or discovered by the inventors, its disclosure and a description of its operation would be expected as part of the application in order to support broad claims, such as claims 1 and 15. This is particularly true because, as discussed above, the teachings that are disclosed in the application require fairly complex and particular structures/operational steps. These structures and steps would be unnecessary if the inventors had known a general case that was not limited to any particular structure (e.g., a quantum device that could achieve the desired results with any receiver, and any coupler, and any detector), and yet the application does not include a disclosure of a general case. This supports a conclusion that the scope of the claims is not commensurate with the teachings of the application.
Other Considerations.
The nature of the invention is quantum communication devices and methods. The components used in the various embodiments were known to one of ordinary skill. For example, one or ordinary skill would be familiar with components such as 50:50 beam-splitters, polarizing beam-splitters, half-wave plates, optical fibers, and single-photon detectors. Therefore, no teachings of how to make these individual components is required.
The application teaches how to arrange these elements with other elements in particular combinations in order to achieve the desired results (e.g., see FIGS. 1 and 2, and the corresponding written description). These teachings are particular and complex. Nonetheless, one or ordinary skill would know how to make and use the disclosed embodiments of the invention from the teachings of the application.
Furthermore, it would have been obvious that some elements may be modified or replaced with other elements known to have the same or similar functionality, and to make some modifications to the particular structures disclosed.
Similarly, one of ordinary skill would also know how to perform other tasks in the present technological area and related to the invention, such as providing power to components (although power supplies and power specifications are not explicitly taught in the application), and splicing/coupling the electrical and optical components together (although this is not explicitly taught in the application), and managing the temperature of electrical and optical components which are susceptible to performance degradation and undesirable operational variations based on temperature (although this is not explicitly taught in the application). Although this is not an exhaustive list, the obvious modifications based on the disclosure and the knowledge of one or ordinary skill are nonetheless of a limited scope.
However, these modifications do not address the issues raised above regarding the disparity between the scope of the claims and the teachings of the application.
Experimentation.
As discussed above, the claims include many possible operations or method steps and the application does not teach the full scope of the claims. As a result, if one of ordinary skill were to attempt to make and use the full scope of the claims, it would require making, testing, or otherwise evaluating all (or at least a very large number of) possible combination of receiver components, coupling arrangements, and detector components within the scope of the claims to find what works to perform the claimed functionality. This results in a practically unlimited number of embodiments that would need to be made, tested, or otherwise evaluated to determine which embodiments within the scope of the claims are operative and which are inoperative. In other words, would require almost infinite experimentation in order to make and use the full scope of the claims.
This supports a finding that undue experimentation would be required to make and use the full scope of the claims.
Conclusion.
After careful consideration the Examiner has concluded that the specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the invention commensurate in scope with these claims. In other words, the specification fails to teach those skilled in the art how to make and use the full scope of the claimed invention without ‘undue experimentation’.
Finally, if Applicant does not want to claim the particular structure and steps of the invention, then the Examiner suggests writing the claims in means-plus-function form and step-plus-function form.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 2009/0190759 (Peev) is the closest art of record. Peev at FIG. 2 illustrates quantum devices 8, 9, each including a receiver 10, a coupling device 30, 30’, and a detector 22, 23.
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The receivers include beam splitters 16-18 and a half-wave plate 19 which output signals into four waveguides 12-15. See also:
[0032] In its measuring unit 8 or 9, respectively, each subscriber station 6, 7 in turn includes an optical module 10, both optical modules 10 in principle being of a similar design so that a single explanation will suffice. Similar to FIG. 1, also in the QKD arrangement 21 according to FIG. 2, a non-polarizing beam splitter 16 is provided in each optical module 10 so as to supply the individual photons either to a first polarizing beam splitter 17--via a .lamda./2 platelet 19--or--directly--to a further polarizing beam splitter 18. In this way, subsequent photon channels 12, 13, 14, 15 are obtained due to the two beam splitters 17, 18, similar as in FIG. 1 always one following the passage path and one following the reflection path of the respective beam splitter 17 or 18. By means of the .lamda./2 platelet 19, a 45.degree. rotation of the polarization plane is introduced again.
The coupling devices 30, 30’ that combine four photon channels into one channel. See:
[0038] The photons which are to be transmitted by a respective one of the four photon channels 12, 13, 14 or 15 to the SPD photodiode 22, or 23, respectively, may be directly fed to the photodiode 22 or 23, respectively, in a light-proof housing, e.g. by respective focusing. An optical guide-dependent transmission of the photons to the photodiodes 22, 23 is, however, more advantageous, in which case a coupler unit 30 or 30' will be provided so as to combine the four photon channels 12 to 15 into one single channel 32 to the photodiode 22 and 23, respectively.
The detector 22, 23 are single photon detectors that detect the output of the coupler 30, 30’. See:
[0038] The photons which are to be transmitted by a respective one of the four photon channels 12, 13, 14 or 15 to the SPD photodiode 22, or 23, respectively, may be directly fed to the photodiode 22 or 23, respectively, in a light-proof housing, e.g. by respective focusing. An optical guide-dependent transmission of the photons to the photodiodes 22, 23 is, however, more advantageous, in which case a coupler unit 30 or 30' will be provided so as to combine the four photon channels 12 to 15 into one single channel 32 to the photodiode 22 and 23, respectively.
This appears to teach at least the receiver arrangement of a half-wave plate and PBSs 105 taught with reference to FIG. 1 of the present application, the single photon detector 106, and a 4:1 coupler.
US 2021/0175976 (Rahman) at FIG. 2A teaches a quantum computer system including a Qubit Source 205, Qubit Links 207, a Qubit Distribution Network 206, and nodes 201 connected by a Classical Communication Network 209.
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Rahman teaches an optical reception system, see:
[0049] The qubit source 205 may include a microscopic system, such as an atom, e.g., atomic nuclei, in which entanglement is shared via a nuclear spin, or a photo in which entanglement may be shared by one or more of polarized or orbital angular momentum. Qubits that utilize photons can be carried or otherwise transported along optical channels. For example, one or more of the quantum channels or links 207 that convey polarized photons can include optical fiber, free space, or a combination of optical fiber and free-space optical links. A processing node 201 adapted for processing photon-based qubits may include a photon detector, e.g., a single photon detector, a polarization detector, a quantum storage element to store qubits received from the quantum entanglement source 205.
In other words, each processing node 201 includes an optical reception system for collecting photons originating from said or from one said source
US 2023/0204863 (Aoki) at FIG. 1 illustrates a quantum computing device 1 including a photon source 11, quantum computing units 13, optical switches 14, and a receiver 16.
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See:
[0023] As shown in an example indicated in FIG. 1, a quantum computing device 1 in accordance with Embodiment 1 includes, for quantum computing, a single photon source 11, M quantum computing units 13-1 to 13-M, M optical switches 14-1 to 14-M, half-wave plates 15-1 to 15-(M+1), a polarization state measurement instrument 16, and an optical fiber 12. Note that M is an integer of not less than 2. In one example, the quantum computing device 1 may be used for distributed quantum computing. However, Embodiment 1 is not limited to this. Alternatively, the quantum computing device 1 may be used for non-distributed quantum computing.
FIG. 2 illustrates the quantum computing units 13 in more detail including the nanofiber 131, end portions 121, and tapered portions 122.
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This also illustrates atoms 132 housed in a vacuum chamber 133 and functioning as qubits interacting with a state of a photon. See:
[0025] As shown in an example indicated in FIG. 2, the quantum computing unit 13-m in accordance with Embodiment 1 includes an optical nanofiber 131-m, an end portion 121a-m of the optical fiber 12, an end portion 121b-m of the optical fiber 12, tapered portions 122a-m and 122b-m, K(m) atoms 132-m (quantum systems each functioning as a qubit interacting with a state of a photon), and a vacuum layer 133-m in which these elements are housed in a vacuum. Note that m = 1, ... , M and M is an integer of not less than 2. Note also that K(m) is an integer of not less than 2 and K(m) atoms 132-m are expressed as ua.sub.1-m, ... , a.sub.K(m)-m. In one example, the atoms 132-m are laser-cooled atoms. However, the present invention is not limited to this.
[0026] The optical nanofiber 131-m is an extremely thin optical fiber having a diameter of not more than a wavelength of light. The whole of the fiber functions as a core, and the vacuum surrounding the fiber functions as a cladding. One end of the optical nanofiber 131-m is optically connected to the end portion 121a-m of the optical fiber 12 via the tapered portion 122a-m. Similarly, the other end of the optical nanofiber 131-m is optically connected to the end portion 121b-m of the optical fiber via the tapered portion 122b-m. That is, this structure can be expressed as follows: In the whole of the fiber including the tapered portions 122a-m and 122b-m (ranging from the end portion 121a-m of the optical fiber 12 to the optical nanofiber 131-m, and further to the end portion 121b-m of the optical fiber 12), a ratio between a core diameter and a cladding diameter is constant or substantially constant. The core of the end portion 121a-m is connected to the core of the optical nanofiber 131-m via the core of the tapered portion 122a-m, and the core of the end portion 121b-m is connected to the core of the optical nanofiber 131-m via the core of the tapered portion 122b-m. The cladding of the end portion 121a-m is connected to the cladding of the optical nanofiber 131-m via the cladding of the tapered portion 122a-m, and the cladding of the end portion 121b-m is connected to the cladding of the optical nanofiber 131-m via the cladding of the tapered portion 122b-m. For example, the core of the optical nanofiber 131-m is integrated with the cores of the tapered portions 122a-m and 122b-m and the cores of the end portions 121a-m and 121b-m. The cladding of the optical nanofiber 131-m is integrated with the claddings of the tapered portions 122a-m and 122b-m and the claddings of the end portions 121a-m and 121b-m. Here, diameters of the core and cladding of the end portion 121a-m are respectively larger than diameters of the core and cladding of the optical nanofiber 131-m. Diameters of the core and cladding of the tapered portion 122a-m gradually increase as their increasing proximity from the optical nanofiber 131-m to the end portion 121a-m. Similarly, diameters of the core and cladding of the end portion 121b-m are respectively larger than the diameters of the core and cladding of the optical nanofiber 131-m. Diameters of the core and cladding of the tapered portion 122b-m also gradually increase as their increasing proximity from the optical nanofiber 131-m to the end portion 121b-m. With such a structure, in the optical fiber 12, light is confined due to a refractive index difference between the core and the cladding. In the optical nanofiber 131-m, light is confined due to a refractive index difference between the cladding and the vacuum. In the tapered portions 122a-m and 122b-m via which the optical fiber 12 and the optical nanofiber 131-m are connected to each other, all the three layers, i.e., the core, the cladding, and the vacuum, contribute to confinement of light.
FIG. 2 also illustrates Bragg gratings 123 in the end portions 121. The Bragg gratings have a reflection bandwidth including the wavelength of the photon propagating through the fiber. See:
[0030] The cores of the end portions 121a-m and 121b-m are respectively provided with fiber Bragg gratings (FBG) 123a-m and 123b-m each having a reflection bandwidth including a wavelength of a photon propagating through the optical fiber 12. Each of the fiber Bragg gratings 123a-m and 123b-m functions as a mirror that reflects a photon.
[0031] By providing the fiber Bragg gratings 123a-m and 123b-m to the cores of the end portions 121a-m and 121b-m, respectively, and adjusting transmittances and reflectances of these fiber Bragg gratings, it is possible to cause a photon entering the optical nanofiber 131-m through the end portion 121a-m to be emitted from the optical nanofiber 13 through the end portion 121a-m.
2021/0105135 (Figueroa) is the closest art of record. Figueroa at FIG. 1 illustrates a quantum network 10 including end nodes 110, intermediate nodes 120, quantum memory 130, and transmission channels 150.
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[0077] With reference to FIG. 1, in use, generally, end nodes 110 both encode and/or decode their information on the single photon level pulses in the form of polarization, whether randomly for QKD applications or deterministically for other use cases, and transmit them along respective transmission channels 150 to intermediate node 120. A quantum memory device 130 may be disposed at different physical locations in each transmission channel 150 to store the polarization qubits and enable selective retrieval to coordinate arrival of the polarization qubits at the intermediate measurement node 120 in temporal synchronization. Regardless of their positions, the quantum memory devices 130 of the present disclosure store qubits while maintaining the integrity thereof; that is, the quantum memory devices 130 enable retrieval of the qubits without damaging the quantum information encoded thereon, e.g., polarization.
[0078] The intermediate node 120 may be configured as a Bell-state measurement station which interferes the two qubits and performs a Bell-state measurement to determine whether the two-qubit state is an entangled state. If the Bell-state measurement is successful (e.g., it detects entanglement), then the end nodes 110 can establish a quantum correlation between the qubits they sent. An eavesdropper attempting to intercept the qubits may not reconstruct the qubit sequence of the end nodes 110 from the Bell-state measurement results, and therefore intermediate node 120 can communicate the coincidence detections classically to the end nodes 110. The qubits may be single photons encoded with quantum information in their quantum feature, e.g., polarization.
[0079] The Bell-state measurement station of the intermediate node 120, with momentary additional reference to FIG. 5, more specifically, includes a Non-Polarizing Beam Splitter (NPBS) at which the qubits retrieved from the quantum memory devices 130 interfere, and two single-photon detectors or Single-Photon Counting Modules (SPCMs) placed at the output arms of the NPBS to generate a signal every time they record a hit. Intermediate node 120 is described in greater detail below with reference to FIG. 5. This is sufficient to perform an HOM check detailed below. However, to extract the polarization information of transmitted qubits, a second set of polarizing beam splitters (PBS) is used sequentially in the optics path to the NPBS. More specifically, for a Hong-Ou-Mandel (HOM) interference check, as detailed below, the polarizations of Horizontal (H) and Vertical (V) can be summed and the polarizations of Diagonal (D) and Antidiagonal (A) can be summed such that only two detectors are required. However, to enable use of intermediate node 120 to both perform a HOM check and extract the polarization information of transmitted qubits, intermediate node 120 includes two sets of polarizing beam splitters (PBS) for a total of four (4), thus enabling detection of each of the H, V, D, and A polarizations.
FIGS. 2-4A illustrates other embodiments in which the network is expanded.
FIG. 10A illustrates another embodiment of the quantum network 1100 including end nodes 1110, an intermediate node 1120, and first and second entanglement photon source nodes 1140.
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See also:
[0122] FIGS. 10A-10C schematically illustrate, within increasing levels of control, communication, and/or feedback, an exemplary quantum network 1100 in accordance with the present disclosure. To the extent consistent, any of the aspects and features detailed above with respect to the other networks and/or components thereof may be utilized in conjunction with network 1100, and vice versa. Network 1100 includes first and second end nodes 1110, an intermediate node 1120, and first and second entanglement photon source nodes 1140. Although illustrated in this configuration, other suitable configurations and/or expanded networks are also contemplated.
There are also first and second quantum memory devices 1130 along the first and second quantum transmission channels 1150 connecting the entanglement photon source nodes 1140 and the Bell State Measurement (BSM) decoding module in the intermediate node 1120. See:
[0072] One or more of the intermediate nodes 120 includes a polarization (or other quantum feature) decoding module, e.g., a Bell-State Measurement (BSM) station, and is described in greater detail below with reference to FIG. 5.
[0123] Referring to FIG. 10A, similarly as detailed above, first and second entanglement photon source nodes 1140 are configured to generate first and second entangled pairs of photons that are transmitted along transmission channels 1150. More specifically, one photon of each pair is transmitted along a transmission channel 1150 including a quantum memory device 1130 to enable synchronized receipt of the photons at the intermediate node 1120. The intermediate node 1120 performs a Bell-state measurement at the intermediate node 1120, thereby entangling the photons of the first and second pairs via quantum teleportation (entanglement swapping). Further, the intermediate node 1120 is configured to communicate, over a classical communication channel, e.g., via a classical signal, with the end nodes 1110 such as, for example, to indicate the results obtained from the Bell-state measurement at the intermediate node 1120, the results of the coarse interference check and/or the fine HOM check at the intermediate node 1120, other feedback and/or control information, etc.
In other words, the quantum memory devices 1130 receive and then synchronizes the receipt of the photons for the BSM decoding module at the intermediate node 1120. When the intermediate node receives the photons, it performs a Bell-state measurement, thereby entangling the photons via quantum teleportation (entanglement swapping).
The intermediate node 1120 also communicates with the end nodes 1110 via a classical communication channel.
[0124] Referring to FIG. 10A, end nodes 1110 can use the shared entangled pair for any application, in this example to establish a quantum repeater enhanced MDI-QKD network by each performing a similar measurement to the Bell-state measurement node 1120 using one entangled photon and one randomly polarized photon. In order to verify the transmitted secret key, end nodes 1110 need to know the result of all the measurements, transmitted to each node via a classical/digital communication link.
US 2023/0028556 (Chiesa) at FIG. 1A illustrates a communication network 100 including nodes 101, channels 106, and a controller 108.
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FIG. 1B is a detailed illustration of a node 101.
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Any inquiry concerning this communication or earlier communications from the examiner should be directed to DARREN WOLF whose telephone number is (571)270-3378. The examiner can normally be reached Monday through Friday, 7:00 AM to 3:00 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, KENNETH N. VANDERPUYE can be reached at 571-272-3078. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/DARREN E WOLF/Primary Examiner, Art Unit 2634
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