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 .
DETAILED OFFICE ACTION
Priority
Acknowledgment is made of applicant's claim for foreign priority based on an application filed in KR on 2024/03/22. It is noted, however, that applicant has not filed a certified copy of the KR1020240039860 application as required by 37 CFR 1.55.
Should applicant desire to obtain the benefit of foreign priority under 35 U.S.C. 119(a)-(d) prior to declaration of an interference, a certified English translation of the foreign application must be submitted in reply to this action. 37 CFR 41.154(b) and 41.202(e). Failure to provide a certified translation may result in no benefit being accorded for the non-English application.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 2024-10-04 in compliance with the provisions of 37 CFR 1.97 has been considered by the examiner and made of record in the application file.
Claim Status
Claims 1-12 are pending in this application and are under examination in this Office Action. No claims have been allowed.
Specification
The disclosure is objected to because of the following informalities and internal inconsistencies. Appropriate correction is required. Any amendment must be supported by the original disclosure and must not introduce new matter.
The expression "to an outside" in paragraphs [0012] and [0050]
Paragraphs [0012] and [0050] state that circulator 410 outputs the optical signal output from phase modulator 420 "to the outside." The expression is unidiomatic and does not identify the intended output relation or boundary. Applicant is required to clarify the expression consistently in the specification and claim 2 without introducing new matter.
Reference numeral 12 in paragraph [0036] and Figure 1
Paragraph [0036] states that sender 10 "encodes information for generating a secret key into the optical pulse 12." Figure 1, however, identifies reference numeral 12 as the rectangular ENCODING block. Applicant is required to correct the description or the drawing so that reference numeral 12 consistently identifies the same element throughout the disclosure.
The stated operation of polarization controllers 311-1 and 311-2 in paragraph [0058]
Paragraph [0058] states that first polarization controller 311-1 and second polarization controller 311-2 may "measure the states" of the respective optical signals. In contrast,
paragraphs [0055]-[0059], claim 6, and Figure 4 describe the polarization controllers controlling or processing polarization before the signals are supplied to polarization
beam splitters 312-1 and 312-2, while photodetectors 321-1 through 321-4 perform the measurement. Applicant is required to clarify the stated operation of the polarization controllers and use consistent terminology throughout the disclosure.
The expressions "same speed" and "random speed" in paragraphs [0020], [0072], and [0079]
Paragraphs [0020] and [0072] state that the detector-driving signal has "the same speed as the optical signal," and paragraph [0079] states that the photodetectors operate at a "random speed." The disclosure does not identify whether "speed" refers to propagation velocity, pulse-repetition frequency, detector-gating frequency, clock rate, symbol rate, or another measurable timing parameter. Applicant is required to clarify the intended technical parameter consistently throughout the disclosure without introducing new matter.
(e) Typographical error in paragraph [0087]
Paragraph [0087] identifies reception apparatus 300 as "Chalie (C)." The apparent typographical error should be corrected to "Charlie (C)."
Claim Objections
Claims 2 and 11 are objected to because of the following informalities. Appropriate correction is required.
Regarding claim 2
Claim 2 recites that the circulator outputs an optical signal output from the phase modulator "to an outside." The expression "to an outside" is unidiomatic. Applicant is required to revise the expression so that the intended output relation is stated in proper idiomatic English, consistent with the original disclosure and without introducing new matter.
Regarding claim 11
Claim 11 recites that the electronic control board "arranges only results satisfying the Bell state measurement." The expression "arranges only results" is unidiomatic. Applicant is required to clarify the intended processing operation using terminology supported by the original disclosure and without introducing new matter.
Double Patenting
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the "right to exclude" granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the claims at issue are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); and In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on a nonstatutory double patenting ground provided the reference application or patent either is shown to be commonly owned with this application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b). The filing of a terminal disclaimer by itself is not a complete reply; the terminal disclaimer must be accompanied by a reply requesting reconsideration of the rejection. See MPEP §§ 804 and 1490.
The USPTO Internet website contains terminal disclaimer forms that may be used. The filing date of the application determines the appropriate form. A web-based eTerminal Disclaimer that meets all requirements may be auto-processed and approved upon submission.
Claim 1 is provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claim 2 of copending Application No. 18/378,295 in view of Wang et al. (US20220247557A1). Although the claims at issue are not identical, they are not patentably distinct from each other for the reasons set forth below.
Common ownership, overlapping inventive entity, and reference-application status. The present application identifies Electronics and Telecommunications Research Institute (ETRI) as the applicant. Application No. 18/378,295 likewise identifies ETRI as the applicant. The present application names O-Sung Kwon, Chang-Ho Hong, Seok Kim, and Jin-Gak Jang as inventors, and Application No. 18/378,295 names each of those four individuals among its inventors. Accordingly, the applications appear commonly owned and have overlapping inventive entities. The Issue Notification dated July 22, 2026 identifies projected U.S. Patent No. 12,700,995 and a projected issue date of August 4, 2026. As of the mailing date of this action, July 28, 2026, the reference application has not yet issued and remains pending. Therefore, the rejection is provisional. See MPEP §§ 804, 822, and 1490.
The present application has a later patent-term filing date than Application No. 18/378,295. Accordingly, the one-way test is applied: whether the invention defined by present claim 1
would have been an obvious variation of the invention defined by reference claim 2. See MPEP § 804, subsection II.B.4.
(a) With respect to claim 1, current amended claim 2 of Application No. 18/378,295, including the limitations of current amended claim 1, includes the similar limitations underlined below. Claims 1 and 2 of the reference application were amended in the Amendment filed March 2, 2026 and were allowed in the Notice of Allowability dated April 7, 2026. The comparison below uses the current amended and allowed claim language rather than the superseded originally published claim language.
Present Application
Copending Application No. 18/378,295 - Current Amended/Allowed Claims
As per claim 1, An apparatus for quantum key distribution (QKD) transmission, comprising:a light source for generating an optical signal; andan encoder for performing polarization or phase encoding of the optical signal according to a protocol.
As per current amended claim 2 (including current amended claim 1), A quantum key distribution apparatus, comprising:a light source that generates and outputs an optical pulse having a single photon,wherein the quantum key distribution apparatus is configured such that:the optical pulse in which information for private key generation is included is transmitted to multiple receivers, respectively, through different communication paths, andthe light source generates the optical pulse at a speed higher than an optical pulse measurement speed of each of the multiple receivers by a multiple of a number of multiple receivers;further comprising:an encoder that encodes private key information into the optical pulse generated by the light source;an optical splitter that divides and outputs optical pulses in which the private key information is encoded into communication paths corresponding to the number of multiple receivers; andmultiple switches that turn on/off the communication paths connected to the multiple receivers, respectively.
Current reference claim 2 depends from current reference claim 1. Current reference claim 1 is directed to a quantum key distribution apparatus and expressly recites a light source that generates and outputs a single-photon optical pulse. Current reference claim 2 further expressly recites an encoder that encodes private-key information into the optical pulse generated by the light source. These limitations correspond to present claim 1's QKD transmission apparatus, light source for generating an optical signal, and encoder for encoding
that optical signal. The additional multiple-receiver, pulse-generation-speed, optical-splitter, and switch limitations of current reference claims 1 and 2 narrow the reference apparatus and do not remove the shared QKD transmitter, light-source, and encoder structure.
The feature of present claim 1 not expressly required by current reference claim 2 is: "the encoder [is] for performing polarization or phase encoding of the optical signal according to a protocol."
However, within analogous QKD art, Wang expressly teaches this limitation. Wang is directed to a "Quantum Key Distribution Device Capable of Being Configured with Multiple Protocols" and states in the Abstract: “The phase modulation is completed with a Sagnac ring device composed of a single polarization phase modulator, a polarization beam splitter and a Faraday rotator ... thus realizing a quantum key distribution device which can be configured with multiple protocols.” [Wang, Abstract].
Wang further states: “The present invention relates to the field of quantum communication, especially a quantum key distribution device that can be configured with multiple protocols.” [Wang, ¶ [0002]].
Wang identifies the compatible protocols as including BB84, reference-frame-independent (RFI), six-state, and SARG protocols. [Wang, Abstract; ¶¶ [0003]-[0005]].
Regarding the transmitter structure, Wang states: “A quantum key distribution device that can be configured with multiple protocols includes a sender ... [and] the sender includes the sender-side main control board, laser ... circulator CIR1 ... and a phase encoding module.” [Wang, ¶ [0007]].
Wang further states: “One output end of CIR1 is connected to the phase encoding module, which is used for the phase encoding of the quantum light.” [Wang, ¶ [0011]; FIG. 1].
Accordingly, current reference claim 1 supplies the QKD apparatus and the light source, and current reference claim 2 supplies the encoder for encoding private-key information into the generated optical pulse. Wang supplies the specific, protocol-dependent phase encoding performed by the encoder. Because present claim 1 is written in the disjunctive - "polarization or phase encoding" - Wang's express phase encoding satisfies that limitation.
One of ordinary skill in the QKD art would have been motivated to implement the encoder recited by current claim 2 of Application No. 18/378,295 as Wang's known phase-encoding module and to operate that encoder according to a selected QKD protocol. The reference claims already require a QKD light source and an encoder that places private-key information into the generated optical pulse. Wang teaches that phase encoding is a known way to perform that same QKD encoding function and that configuring a common QKD apparatus for multiple protocols avoids the device duplication and inefficiency associated with separate single-protocol systems. [Wang, ¶¶ [0002]-[0005], [0007], [0011]].
The proposed modification would have required only the predictable use of a known QKD phase-encoding module according to its established function - encoding private-key information into the optical pulse in accordance with a selected QKD protocol. The light source and encoder of current reference claims 1 and 2 would continue to perform the same respective functions, while Wang's protocol-dependent phase encoding would specify the known physical encoding technique used by the encoder. The multiple-receiver paths, pulse-
generation-speed relationship, optical splitter, and switches recited by the reference claims would continue to operate for their established purposes. The combination therefore would have yielded no unexpected result and would have predictably produced the apparatus recited in present claim 1.
After the above modification, the invention defined by current reference claim 2, including current reference claim 1, contains every limitation of present claim 1. The additional multiple-receiver, pulse-generation-speed, optical-splitter, and switch limitations define a narrower species within the broader scope of present claim 1 and do not render present claim 1 patentably distinct. Therefore, under the one-way obviousness-type double-patenting test, present claim 1 would have been an obvious variation of current reference claim 2.
Accordingly, claim 1 is provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over current amended claim 2 of copending Application No. 18/378,295, including the limitations of current amended claim 1, in view of Wang et al. (US20220247557A1).
No double-patenting rejection is made against claims 2-12 on this record. The current amended and allowed claims of Application No. 18/378,295 do not themselves recite the present application's circulator/phase-modulator/Faraday-mirror arrangement, voltage sequence, two-branch receiver decoder, four-detector Bell-state-measurement arrangement, electronic-control-board processing, or 0-degree/45-degree controller settings. Limiting the provisional rejection to claim 1 preserves the strongest and most defensible claim-to-claim relationship.
Claim Rejections - 35 USC § 112(b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claim 10 is rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
(a) Regarding claim 10,
Claim 10 recites that "the electronic control board drives the first to fourth photodetectors using the driving signal at a same speed as the optical signal."
Claim 10 is indefinite for two independent reasons. First, the expression "the optical signal" lacks clear antecedent basis in the incorporated claims. Claim 5 introduces "a received optical pulse." Claim 6 introduces plural "optical signals transmitted from two or more transmission apparatuses," a split first beam, a split second beam, and signals output from the first and second polarization controllers. Claim 7 introduces respective output signals split in the first and second polarization beam splitters. Claim 8 then recites plural "arrived optical signals." Claim 10 changes to the singular expression "the optical signal" without identifying whether the expression refers to the received optical pulse, one of the two transmitted optical signals, one
of the split beams, one of the polarization-beam-splitter output signals, all such signals collectively, or another optical signal. Because the dependency chain contains several distinct optical signals and signal portions, the referent of "the optical signal" is not reasonably certain.
Second, the phrase "at a same speed as the optical signal" does not identify an objective technical parameter. The physical propagation velocity of an optical signal is not the same type of quantity as an electronic detector-driving rate. In the context of the disclosed QKD receiver, "speed" may reasonably refer to optical pulse-repetition frequency, detector-gating frequency, clock rate, symbol rate, sampling rate, coincidence-counting rate, or physical propagation velocity. These are technically different parameters and define materially different detector-driving relationships. Claim 10 does not state which parameter is being compared or what constitutes the recited sameness.
The specification does not resolve either ambiguity. Paragraphs [0020] and [0072] repeat the phrase "same speed as the optical signal" without defining the relevant signal or measurable parameter, and paragraph [0079] separately states that the photodetectors operate at a "random speed." Figure 4 shows detector-driving paths between electronic control board 322 and photodetectors 321-1 through 321-4, but does not establish the particular timing or rate relationship required by claim 10. Accordingly, a person of ordinary skill in the art cannot determine with reasonable certainty which optical signal supplies the comparison standard or which technical parameter must be the same.
Accordingly, claim 10 is indefinite under 35 U.S.C. 112(b).
Claim Interpretation - 35 USC § 112(f)
The following is a quotation of 35 U.S.C. 112(f):
(f) ELEMENT IN CLAIM FOR A COMBINATION.—An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
The limitation "a measuring device for detecting polarization or a phase of the optical pulse" in claim 5 is interpreted under 35 U.S.C. 112(f).
Although the limitation does not use the word "means," the term "device" is a generic placeholder; the modifier "measuring" describes the function to be performed; and the claim does not recite within that limitation sufficient structure for performing the entire function of detecting polarization or phase. Accordingly, the presumption that 35 U.S.C. 112(f) does not apply is overcome.
The claimed function is detecting polarization or a phase of the optical pulse. The corresponding structure disclosed in the specification is measuring device or detector 320 comprising first through fourth photodetectors 321-1, 321-2, 321-3, and 321-4 arranged to receive the respective optical outputs from first and second polarization beam splitters 312-1 and 312-2, as described in paragraphs [0017], [0057], and [0060]-[0063] and illustrated in Figure 4, and equivalents thereof.
Because the specification discloses and clearly links the above structure to the claimed detecting function, no separate rejection under 35 U.S.C. 112(b) is made on the basis of the application of 35 U.S.C. 112(f). The limitation is construed to cover the identified corresponding structure and equivalents thereof.
Claim Rejections - 35 U.S.C. § 102
The following is a quotation of 35 U.S.C. 102(a), which forms the basis for the anticipation rejections set forth in this Office Action:
(a) NOVELTY; PRIOR ART.—A person shall be entitled to a patent unless—
(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention; or
(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claim 1 is rejected under 35 U.S.C. 102(a)(1) as being anticipated by Wang et al. (US20220247557A1).
Claim 1
Wang expressly teaches a configurable, multi-protocol QKD transmitting apparatus having a laser light source and a phase encoder controlled according to the selected QKD protocol. Wang was published August 4, 2022, before the March 22, 2024 effective filing date of the present application.
“A quantum key distribution device that can be configured with multiple protocols, proposed by the present invention, includes a sender, a receiver, and a communication channel used to connect the sender and the receiver; the communication channel used to connect the sender and the receiver in the present invention is optical fiber.” [Wang, ¶ [0038]].
“As shown in FIG. 1, the above-mentioned sender includes the sender-side main control board, laser, intensity modulator IM1, the sender F-M interference ring, the first photoelectric tube, the second photoelectric tube, a synchronous laser, intensity modulator IM2, an optical attenuator, the sender Sagnac ring and a wavelength division multiplexing module.” [Wang, ¶ [0039]; FIG. 1].
“Another part of the quantum light outputted by IM2 enters circulator CIR1. One output end of CIR1 is connected to the sender Sagnac ring to perform phase encoding on the quantum light.” [Wang, ¶ [0040]].
“The above-mentioned sender Sagnac ring includes single-polarization phase modulator PM1, Faraday rotator FM3 and polarization beam splitter PBS1. The front bin pulse is divided into H component and V component after passing through polarization beam splitter PBS1. The transmitted H component is phase-modulated by PM1, and then rotated to the polarization direction of V by FM3 and returns to the original optical path; and the V component is rotated to the polarization direction of H by FM3, and then is phase-modulated through PM1 and returns to the original optical path.” [Wang, ¶ [0041], p. 3].
“This device can be compatible with multiple protocols, including BB84 protocol, RFI protocol, the six-state protocol and SARG protocol, and can implement different decoy state schemes.” [Wang, ¶ [0053]].
Accordingly, Wang teaches the claimed “apparatus for quantum key distribution transmission” through the disclosed sender of the configurable QKD device; the claimed “light source for generating an optical signal” through the expressly disclosed laser that outputs quantum light; and the claimed “encoder for performing polarization or phase encoding of the optical signal according to a protocol” through the sender Sagnac phase-encoding ring, phase modulator PM1, polarization beam splitter PBS1, and protocol-selectable operation compatible with BB84, RFI, six-state, and SARG protocols. Every limitation of claim 1 is therefore expressly or inherently disclosed in a single prior-art reference arranged as claimed.
Claim 1 is anticipated by Wang.
Claim 2 is rejected under 35 U.S.C. 102(a)(1) as being anticipated by Dong Wang et al. (CN110620664A).
Claim 2
Dong Wang expressly teaches a phase-and-polarization encoded QKD transmitter having a laser and an encoder formed by a coding circulator, a coding phase modulator, and a Faraday rotating mirror connected to provide a forward pass, reflection, return pass, and output through the circulator. CN110620664A was published December 27, 2019, before the effective filing date of the present application.
“A phase composite with the polarization coding quantum key distribution system, comprising a sending end and a receiving end, the sending end comprises a laser connected in turn, the intensity modulator, phase encoding module, a polarization coding module and an attenuator.” [Dong Wang, Abstract and Summary, pp. 1-2].
“The polarization coding module comprises a coding circulator connected in turn, a code phase modulator and encoding the Faraday rotating mirror ... coding the second port of the circulator is connected with code phase modulator, coding of the circulator connected attenuator.” [Dong Wang, Summary, p. 2; claims 2-3, pp. 5-6].
“The polarization encoding module 140 comprises a coding circulator 141, encoding phase modulator 142 and encoding Faraday rotating mirror 143 ... the second port of coding
circulator 141 connects the encoding phase modulator 142, and the coding circulator port 141 is connected with the attenuator 150.” [Dong Wang, Detailed Description, pp. 3-4; FIGS. 1-3].
“The light pulse enters the coding circulator CIR ... into code phase modulator PMA2, [is] reflected [by the] Faraday rotating mirror FM, [and] again [passes] through the encoding phase modulator PMA2. By modulating the coding phase modulator PMA2 [the system] can change the phase difference between the H and V components so as to generate the polarization.” [Dong Wang, working-principle discussion, p. 4].
Dong Wang therefore teaches the parent limitations of claim 1 through the expressly disclosed QKD sending end, laser, phase-encoding module, and polarization-encoding module used in a BB84-type QKD system. The coding circulator 141 directs the optical signal from its connected input toward phase modulator 142; the signal passes through phase modulator 142, is reflected by Faraday mirror 143, returns through phase modulator 142, and is routed from the circulator toward attenuator 150, which is outside the encoder. Phase modulator 142 applies the controlled relative phase that produces the encoded polarization state, and Faraday mirror 143 performs the claimed reflection. Thus, the reference discloses the claimed circulator, phase modulator, Faraday mirror, forward and return optical path, protocol-based phase or polarization encoding, and circulator output to the external downstream optical path. Every limitation of claim 2 is disclosed by Dong Wang, and claim 2 is anticipated.
Claim 5 is rejected under 35 U.S.C. 102(a)(1) as being anticipated by Guo et al. (US20190312723A1).
Claim 5
Guo expressly teach a QKD reception apparatus that performs protocol-based polarization and phase demodulation using polarization controllers and polarization beam splitters and detects the resulting optical states with four photodetectors. Guo was published October 10, 2019, before the March 22, 2024 effective filing date of the present application.
“A system includes an Alice transmitting terminal, a wavelength division multiplexing (WDM) unit and a plurality of Bob terminals for receiving a plurality of photons of different wavelengths ... each Bob terminal includes a second polarization controller, a third polarization controller, a fourth polarization controller, a third polarization beam splitter, a fourth polarization beam splitter ... a first photon detector, a second photon detector, a third photon detector and a fourth photon detector.” [Guo, Abstract; ¶ [0011]; FIGS. 3-4].
“Polarization demodulation is performed by the second polarization beam splitter of the Bob terminal, and the horizontally-polarized pulse is selected to pass through the third polarization controller when a polarization bit is ‘0’; and the vertically-polarized pulse is selected to pass through the fourth polarization controller when the polarization bit is ‘1’.” [Guo, ¶ [0013]; ¶ [0053]].
“After the pulse is output from the third polarization controller and passes through the third polarization beam splitter ... the first photon detector and the second photon detector make
identification responses ... [and] after the pulse is output from the fourth polarization controller and passes through the fourth polarization beam splitter ... the third photon detector and the fourth photon detector make identification responses.” [Guo, ¶¶ [0014]-[0015], [0054]-[0055]; FIG. 3].
“The first photon detector, the second photon detector, the third photon detector and the fourth photon detector make responses according to the phase difference of the pulses.” [Guo, ¶ [0021]].
Accordingly, Guo teaches the claimed “apparatus for QKD reception” through the expressly disclosed Bob terminal of the phase-and-polarization QKD network. The second polarization beam splitter, third and fourth polarization controllers, and downstream third and fourth polarization beam splitters collectively perform decoding by selecting, rotating, and resolving polarization according to the QKD operating basis. The first through fourth photon detectors receive the respective outputs of the two downstream polarization beam splitters and determine the encoded optical state from the detector response associated with the phase difference. Under the 35 U.S.C. 112(f) interpretation stated above, this four-detector/two-polarization-beam-splitter arrangement is the same or an equivalent structure for performing the claimed function of detecting polarization or phase. Every limitation of claim 5 is therefore disclosed in a single reference arranged as claimed.
Claim 5 is anticipated by Guo.
Claim Rejections - 35 U.S.C. § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for the obviousness rejections set forth in this Office Action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
As reiterated by the Supreme Court in KSR, and as set forth in MPEP § 2141, the factual inquiries of Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), applied for establishing a background for determining obviousness under 35 U.S.C. 103, are summarized as follows:
1. Determining the scope and content of the prior art;
2. Ascertaining the differences between the prior art and the claims at issue;
3. Resolving the level of ordinary skill in the pertinent art; and
4. Considering objective evidence indicative of obviousness or non-obviousness, if present.
This application currently names joint inventors. In considering patentability of the claims, the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s), absent evidence to the contrary. Applicant is advised of the obligation under 37 C.F.R. § 1.56 to identify any inventor, effective-filing-date, or common-ownership facts material to the applicability of 35 U.S.C. 102(b)(2)(C) to potential 35 U.S.C. 102(a)(2) prior art.
Claims 3 and 4 are rejected under 35 U.S.C. 103 as being unpatentable over Dong Wang et al. in view of Zavriyev et al. (US20070160212A1).
Claim 3
With respect to claim 3, all limitations of claim 2 are taught by Dong Wang for the reasons stated above. Claim 3 further requires that the optical signal be input to the phase modulator at 45 degrees, that a positive operating voltage be applied during the forward passage through the phase modulator, and that a negative operating voltage be applied during the return interval following reflection from the Faraday mirror.
“The circulator CIR encoding two-port of fibre phase modulator PMA2 [is connected] with the coding input end for 45 degrees ... the light pulse enters the coding circulator CIR, polarization rotating 45 degrees ... [is] reflected [by the] Faraday rotating mirror FM, [and] again [passes] through the encoding phase modulator PMA2.” [Dong Wang, working-principle discussion, translated p. 4; FIGS. 1-3].
Thus, Dong Wang expressly supplies the 45-degree launch and the same phase modulator being traversed before and after Faraday-mirror reflection. Dong Wang does not expressly label the respective timed drive values with the mathematical signs “+” and “-.” However, Zavriyev expressly teaches synchronized positive and negative QKD basis voltages in a two-way Faraday-mirror modulator environment.
“The methods include setting the voltage (VB) of Bob’s modulator (MB) to a positive value and then adjusting the voltage (VA) of Alice’s modulator (MA) in both the positive and
negative direction to obtain overall relative phase modulations that result in maximum and minimum photon counts.” [Zavriyev, Abstract; ¶ [0015]; FIG. 2].
“Bob’s modulator voltage is then set to a negative value and the process repeated.” [Zavriyev, Abstract; ¶ [0017]].
“Alice includes a phase modulator MA coupled at one end to optical fiber link FL and at the opposite end to a Faraday mirror FM ... [and] the operation of the phase modulators MA and MB is coordinated by synchronization signals.” [Zavriyev, ¶¶ [0022]-[0023]; FIG. 1].
“The pulses P1 and P2 pass through Alice’s modulator MA and reflect off of Faraday mirror FM ... [and] the timing of the activation of modulator MA to coincide with the arrival of pulse P2 is provided by the synchronization signal.” [Zavriyev, ¶¶ [0026]-[0027]].
For purposes of applying the prior art, the claim language stating that the negative operating voltage is applied “when the optical signal is reflected from the Faraday mirror” is read consistently with the applicant’s own description as referring to the reflected return interval in which the signal again traverses the phase modulator. This reading does not eliminate the separate clarity concern; it merely applies the most technically coherent interpretation for the prior-art analysis.
One of ordinary skill in the art would have been motivated to apply Zavriyev’s known positive and negative, pulse-synchronized QKD basis voltages to the temporally separated forward and return passages of Dong Wang’s double-pass phase modulator. Dong Wang already teaches equal H and V components produced by the 45-degree launch, a phase modulator traversed on both passes, and a Faraday mirror defining the return path. Zavriyev teaches that opposite-
polarity basis voltages and synchronized activation are conventional tools for selecting opposite relative phase states in two-way QKD. Applying a positive drive during the first passage and a negative drive during the reflected return passage would have predictably increased the differential phase imposed over the two passages and generated the intended complementary polarization states. The modification would require no new optical component and would not change the established functions of the circulator, phase modulator, or Faraday mirror; it would merely supply known timed voltage values to the known modulator. The result would have been the predictable positive-forward/negative-return sequence recited in claim 3.
Accordingly, claim 3 would have been obvious.
Claim 4
With respect to claim 4, all limitations of claim 2 are taught by Dong Wang as discussed above. Claim 4 further requires a 45-degree input and application of a positive or negative operating voltage while the optical signal passes through the phase modulator.
“The circulator CIR encoding two-port of fibre phase modulator PMA2 [is connected] with the coding input end for 45 degrees ... by modulating the coding phase modulator PMA2 [the system] can change the phase difference between the H and V components so as to generate [the polarization states].” [Dong Wang, translated p. 4; FIGS. 1-3].
“The methods include setting the voltage of Bob’s modulator to a positive value and then adjusting the voltage of Alice’s modulator in both the positive and negative direction ... Bob’s
modulator voltage is then set to a negative value and the process repeated.” [Zavriyev, Abstract, p. 1; ¶¶ [0015]-[0017]].
One of ordinary skill in the art would have been motivated to use either a positive or a negative QKD basis voltage during passage of the 45-degree-polarized signal through Dong Wang’s phase modulator because the sign and magnitude of the applied voltage select the sign and magnitude of the induced relative phase shift between the equal H and V components. Zavriyev expressly teaches both voltage polarities as normal QKD basis values and teaches synchronizing the voltage to the pulse passage. The proposed modification would use the phase modulator for its established purpose, would preserve every optical connection disclosed by Dong Wang, and would predictably generate selectable complementary polarization or phase states. Claim 4 therefore would have been obvious.
Claims 6 and 7 are rejected under 35 U.S.C. 103 as being unpatentable over Guo et al. in view of Bunandar et al. (US20160352515A1).
Claim 6
With respect to claim 6, all limitations of claim 5 are taught by Guo as stated above. Claim 6 additionally requires optical signals from two or more transmission apparatuses, a beam splitter that divides those received signals into first and second beams, and first and second polarization-controller/polarization-beam-splitter branches respectively receiving those beams.
“The scheme includes at least two sending chips (usually referred to as Alice and Bob), which encode signals in single photons through either time-bin encoding or polarization encoding, as well as a receiver chip (usually referred to as Charlie), which measures the signals in the maximally entangled Bell basis.” [Bunandar, ¶ [0002]].
“The receiver 200 includes two input waveguides 210a and 210b to receive qubits sent by Alice and Bob, respectively. A 50-50 coupler 220 combines the two signals received by the two input waveguides ... [and] two detectors 230a and 230b are coupled to the two output ports of the coupler 220 to make Bell measurements.” [Bunandar, ¶ [0071]; FIG. 2].
“The receiver chip can include a 50-50 coupler followed by two PBSs. One input port of each PBS is in vacuum, and a single photon detector is placed on each output port of the PBS.” [Bunandar, ¶ [0107]; FIG. 12A].
“Each Bob terminal comprises ... a third polarization controller, a fourth polarization controller, a third polarization beam splitter, a fourth polarization beam splitter ... a first photon detector, a second photon detector, a third photon detector and a fourth photon detector.” [Guo, ¶ [0011]; FIGS. 3-4].
One of ordinary skill in the art would have been motivated to incorporate Bunandar’s two-transmitter/50:50-coupler MDI input stage into Guo’s two independently controllable polarization-analysis branches. Both references concern polarization-resolved QKD reception. Bunandar supplies the known MDI architecture in which Alice and Bob deliver optical qubits to a common beam splitter and the two coupler outputs are separately analyzed. Guo supplies a known controller followed by a polarization beam splitter in each of two parallel analysis
branches. Placing Guo’s first controller/PBS branch on the first output of Bunandar’s 50:50 coupler and Guo’s second controller/PBS branch on the second output would compensate polarization rotation, align each output to the chosen analysis basis, and preserve polarization information before detection. The 50:50 coupler would continue to combine/divide the Alice and Bob inputs for two-photon interference, while each controller and PBS would perform its established polarization-control and separation function. The modification would therefore have produced the exact first-beam/first-controller/first-PBS and second-beam/second-controller/second-PBS arrangement of claim 6 with predictable results.
Accordingly, claim 6 would have been obvious.
Claim 7
With respect to claim 7, all limitations of claim 6 are taught by Guo and Bunandar for the reasons stated above. Claim 7 additionally requires first and second photodetectors receiving the respective outputs of the first polarization beam splitter and third and fourth photodetectors receiving the respective outputs of the second polarization beam splitter.
“A single photon detector is placed on each output port of the PBS.” [Bunandar, ¶ [0107]].
“After the pulse ... passes through the third polarization beam splitter 303 ... the first photon detector 305 and the second photon detector 306 make identification responses ... [and] after the pulse ... passes through the fourth polarization beam splitter 308 ... the third photon detector 310 and the fourth photon detector 311 make identification responses.” [Guo, ¶¶ [0054]-[0055]; FIG. 3].
One of ordinary skill in the art would have been motivated to provide one single-photon detector at each of the four PBS output ports because each polarization beam splitter spatially separates two complementary polarization outcomes and both outputs must be observed to preserve the complete measurement result. Bunandar expressly teaches a detector at every PBS output in the Bell analyzer, and Guo expressly numbers the two detectors associated with each of the two branch PBSs. The four detectors would perform their ordinary, established function and would predictably yield the branch-output click patterns required for the QKD measurement. Claim 7 therefore would have been obvious.
Claims 8, 9, and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Guo et al. in view of Bunandar et al. and further in view of Wang et al., and Legre et al. (WO2012046135A2).
Claim 8
With respect to claim 8, all limitations of claim 7 are taught by Guo and Bunandar for the reasons stated above. Claim 8 further requires an electronic control board that generates a driving signal for the first through fourth photodetectors, receives measurement results from those photodetectors, and analyzes the results.
“The above-mentioned receiver includes the receiver-side main control board, a wavelength division demultiplexing module, the third photoelectric tube and a decoding module.” [Wang, ¶ [0045]; FIG. 2].
“The wavelength division demultiplexing module ... convert[s] the synchronous light into an electrical signal through the third photoelectric tube and generate[s] a synchronous clock signal. The quantum light then enters the decoding module.” [Wang, ¶ [0046]].
“The receiver-side main control board collects signals from the first photon detector, the second photon detector and the third photoelectric tube, and obtains the synchronous clock signal from the signal of the third photoelectric tube while processing the signals received by the first photon detector and the second photon detector to obtain the key.” [Wang, ¶ [0051]].
Wang thus expressly teach the receiver board receiving and analyzing photon-detector outputs together with a synchronous clock.
Legre additionally teach the electronic generation and delivery of detector activation parameters and the return and processing of detector event data.
“If the receiver 120 works with a single-photon detector 200-1 based on APD working in gated mode, the setting parameter values sent by the alarm subsystem 400 are the bias voltage applied on the APD 320, the time when the activation gate is applied, and the amplitude and width of the activation gate.” [Legre, p. 19, lines 27-35; FIG. 7, step 740].
“In a sixth step 760, if an electrical signal has been received from the single-photon detector 200, the alarm subsystem 400 sends the time of the detection and the setting parameter values (efficiency and/or activation timing) at the time of the detection to the electronic driving circuit 300.” [Legre, p. 20, lines 1-8; FIG. 7, step 760].
“In a seventh step 770, the electronic driving circuit 300 processes the data sent by the alarm subsystem 400. It stores the time of detection and the corresponding efficiency of the single-photon detector 200 in a buffer of the processing unit 123.” [Legre, p. 20, lines 9-24; FIG. 7, step 770].
“In an eighth step 780, the processing unit 123 sorts the data stored in the buffer by efficiency and/or activation timing values and computes for each efficiency and/or activation timing value the measured probability of detection.” [Legre, p. 20, lines 25-34; FIG. 7, step 780].
One of ordinary skill in the art would have been motivated to provide the four-detector Guo/Bunandar receiver with the receiver-side board and detector-driving circuitry taught by Wang and Legre The optical receiver already generates four electrical detector channels whose acceptance windows must be synchronized to expected photon arrival and whose click patterns must be collected and analyzed. Wang teach using one receiver board to recover a synchronous clock and process detector outputs. Legre teach that an electronic detector-control subsystem sends activation-gate timing and related driving parameters to a single-photon detector, receives the detector event time together with the detector settings, and processes and sorts those data. Extending the same parallel electronic interfaces from two detectors to the four detectors expressly disclosed by Guo and Bunandar would have been a routine scaling of identical detector channels, rather than a change in operating principle. Each added channel would receive the same type of synchronized activation control and would return the same type of detection-event data to the common processing board. The resulting board would therefore generate or distribute driving signals to the first through fourth photodetectors, receive the measurement result from each detector, and analyze the resulting four-channel detector pattern exactly as recited in claim 8. The modification would have yielded the predictable benefits of improved timing discrimination, fewer out-of-window detections, and electronic identification of the measurement outcome.
Accordingly, claim 8 would have been obvious.
Claim 9
With respect to claim 9, all limitations of claim 8 are taught by Guo, Bunandar, Wang and Legre for the reasons stated above. Claim 9 further requires the first through fourth photodetectors to perform Bell-state measurement.
“To implement the MDI-QKD protocol, Alice and Bob randomly and independently prepare photon signals in one of the four BB84 states ... [and] these photons are then sent via the quantum channel to Charlie who is instructed to perform a Bell state measurement.” [Bunandar, ¶ [0003]].
“The receiver chip can include a 50-50 coupler followed by two PBSs ... a single photon detector is placed on each output port of the PBS. This chip can measure [two] of the four possible Bell states.” [Bunandar, ¶ [0107]; FIG. 12A].
The four photodetectors do not perform unrelated measurements. Their joint click pattern after the 50:50 coupler and the two polarization beam splitters constitutes the Bell-state measurement. Bunandar expressly identify that function, Guo supply the same four polarization-resolved detector outputs, and the Wang/Legre electronic-control teachings supply synchronized event acquisition and electronic processing of the detector outcomes.
Employing those known components for their established functions would have caused the four detector-event channels to be acquired within the common measurement window and evaluated as the joint detector pattern produced by the Bell analyzer. The result would predictably perform the Bell-state measurement recited in claim 9 without changing the optical or electronic operating principle of any component.
Accordingly, claim 9 would have been obvious.
Claim 11
With respect to claim 11, all limitations of claim 9 are taught by Guo, Bunandar, Wang and Legre as discussed above. Claim 11 additionally requires the electronic control board to retain
or arrange only the results satisfying the Bell-state measurement and to transmit those results to the transmission apparatuses.
“Charlie announces whether or not his Bell state measurements are successful along with the Bell State obtained. Alice and Bob retain only the data that correspond to successful Bell state measurements and discard the rest.” [Bunandar, ¶ [0004]].
“Alice and Bob can send the output of their transmitters to a third party (Charlie), who uses a receiver chip for measurements. Alice and Bob then can generate quantum keys based on the measurements announced by Charlie.” [Bunandar, ¶ [0069]].
One of ordinary skill in the art would have been motivated to configure the electronic board taught by Wang and Legre to classify the synchronized four-detector click patterns as successful
or unsuccessful Bell events, arrange or retain only the successful-event records, and transmit those records to Alice and Bob. Bunandar expressly require Charlie to announce whether the Bell-state measurement succeeded and which Bell state was obtained, and expressly require Alice and Bob to discard the unsuccessful events. The electronic board already receives detector outputs and timing information and performs electronic processing of those data. Implementing the protocol-defined success test in that board would therefore have been the direct and conventional electronic implementation of Bunandar stated MDI-QKD procedure. The modification would reduce storage and communication of unusable events, provide the transmission apparatuses with the exact sifting information required to form correlated keys, and use the board only for its established event-processing and communication functions. The result would have been predictable.
Accordingly, claim 11 would have been obvious.
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Guo et al. in view of Bunandar et al. and further in view of Wang et al. and Legre et al. and further in view of Yuan et al. (US9377356B2).
Claim 10
For purposes of applying the prior art only, and without withdrawing the separate rejection under 35 U.S.C. 112(b), the phrase “using the driving signal at a same speed as the optical signal” is interpreted as requiring detector-driving or detector-gating timing having a repetition frequency synchronized with the repetition frequency and expected arrival times of the received optical pulses.
With respect to claim 10, all limitations of claim 9 are taught by Guo and Bunandar, Wang and Legre for the reasons discussed above. Claim 10 further requires the board to drive the first through fourth photodetectors with a signal synchronized to the optical-pulse rate.
“The laser produces a single optical pulse for each clock signal with a repetition period of T.” [Yuan, col. 9, lines 20-29].
“Photon detectors 251 and 253 are controlled by biasing circuit 255 in accordance with the signal received from clock laser 227.” [Yuan, col. 9, lines 20-25; FIG. 10].
“FIG. 10e is a plot of the gating bias which is in synchronization with the clock bias shown in FIG. 10b. Bob gates his detectors 251, 253 to record only photons in the central peak and not those in the earlier or later satellite peak.” [Yuan, col. 10, lines 58-65; FIG. 10].
One of ordinary skill in the art would have been motivated to distribute Yuan clock-synchronized detector-gating signal from the electronic board to all four detectors of the Guo/Bunandar Bell analyzer. Bell-state identification depends on determining whether detector clicks correspond to the same pair of simultaneously arriving optical pulses. Synchronous gating confines detection to the expected optical-pulse windows, reduces dark and out-of-window counts, associates every click with the correct pulse period, and enables accurate coincidence analysis across all four detector channels. Wang already teach recovery of a synchronous receiver clock and processing detector signals with that clock. Legre teach electronic application of detector activation-gate timing, including the time, amplitude, and width of the activation gate, and the return and processing of the corresponding detection-event timing. Yuan expressly teach that the detector gate is synchronized with the optical clock that produces one optical pulse per clock period. Extending that same synchronized gating signal to four parallel detectors would have been a predictable channel-count increase in which each detector performs the same established gated-detection function. Under the stated interpretation, the combined system would drive the first through fourth photodetectors at the synchronized optical-pulse rate and expected arrival times recited in claim 10.
Accordingly, claim 10 would have been obvious.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Guo et al. in view of Bunandar et al. and further in view of Wang et al. and Legre et al. and further in view of Yuan et al. (GB2441364A).
Claim 12
With respect to claim 12, all limitations of claim 9 are taught by Guo, Bunandar, Wang and Legre as discussed above. Claim 12 further specifies that the first polarization controller is set to 0 degrees and the second polarization controller is set to 45 degrees.
“In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay in an interferometer. Each bit may be represented using two orthogonal states in one of two non-orthogonal bases.” [Yuan, GB2441364A, p. 2].
“For polarisation encoding, one basis may be defined by vertically or horizontally polarising a photon and the other basis is defined by two polarisation states at 45° to the vertical and horizontal states.” [Yuan, GB 2,441,364 A, p. 2].
“Each Bob terminal comprises ... a third polarization controller, a fourth polarization controller, a third polarization beam splitter [and] a fourth polarization beam splitter.” [Guo, ¶ [0011]; FIG. 3].
One of ordinary skill in the art would have been motivated to set Guo et al. first independently controllable polarization-analysis branch to the 0-degree horizontal/vertical reference orientation and the second independently controllable branch to the 45-degree diagonal/antidiagonal orientation taught by Yuan et al. Those settings are the two standard mutually unbiased BB84 polarization bases used by Alice and Bob, and Bunandar et al. expressly teach that Alice and Bob prepare BB84 states before Charlie performs the Bell-state measurement. Guo et al. already provide separate controllers and polarization beam splitters in two parallel detector branches. Assigning the known conjugate basis orientations to those branches would allow the receiver to analyze complementary BB84 polarization orientations without serially reconfiguring a single branch. Each controller and polarization beam splitter would continue to perform its established alignment and polarization-separation function, while the Wang/Legré electronics would continue to acquire and process the resulting synchronized detector events. The numerical settings would therefore have been a routine and predictable configuration of known QKD analysis branches, rather than a new operating principle. Accordingly, claim 12 would have been obvious.
It is noted that any citations to specific, pages, columns, lines, or figures in the prior art references and any interpretation of the reference should not be considered to be limiting in any way. A reference is relevant for all it contains and may be relied upon for all that it would have reasonably suggested to one having ordinary skill in the art. See MPEP 2123.
Conclusion
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/MOHAMMED ABDELRAHEEM/Examiner, Art Unit 2635
/DAVID C PAYNE/Supervisory Patent Examiner, Art Unit 2635
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