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
Claim Status
Claims 1, 3-6, 8, 13, 15, 17, 28-30, 32-34, 36, 43-45, and 54 are pending for examination in this Office Action. Claims 2, 7, 9-12, 14, 16, 18-27, 31, 35, 37-42, and 46-53 are canceled. No claims have been allowed.
Response to Remarks
Applicant's arguments filed 08/25/2026 have been fully considered. The arguments concerning the previously applied grounds are persuasive only to the limited extent expressly stated below; they do not overcome the new and maintained grounds of rejection set forth in this Final Office Action.
Applicant requests withdrawal of the nonstatutory double-patenting rejection based on the electronic terminal disclaimer filed August 25, 2026. The Office agrees. The record shows that the electronic terminal disclaimer directed to the reference application was approved. Accordingly, the prior nonstatutory double-patenting rejection of claims 1, 3-6, 8, 13, 15, 17, 28-30, 33, 34, 36, and 43-45 is withdrawn and is not maintained in this action.
Applicant requests withdrawal of the prior rejections under 35 U.S.C. § 112(b) of claims 6, 17, 30, 32 and 54, and the prior rejection under 35 U.S.C. § 112(d) of claim 6. The Office agrees that the amendments directly address the defects previously identified: claim 6 deletes the alternative single-combiner wording that conflicted with claim 4; claim 17 corrects the P0/P1 identification and introduces the output tuneable gain unit; claim 30 introduces the output tuneable gain unit; and claims 32 and 54 now identify the QKD receiver, standard communication channel, unbalanced interferometer, transmitted optical signal pattern, and the transmitter clock relationship. The prior 35 U.S.C. § 112(b) and 35 U.S.C. § 112(d) rejections are therefore withdrawn and are not maintained in this action.
Applicant argues that Kikawada, the previously applied Wang reference, and Bunandar do not disclose a plurality of electrical pulse signal sources including opposite-polarity electrical pulses. That criticism of the former combination does not overcome the present rejection. The Final Office Action relies on Korzh et al. for the QKD electrical drive architecture. Korzh expressly shows an FPGA driving two RF pulse generators and expressly states that positive and negative electrical pulses in push-pull operation of the two DDM arms produce the QKD time-basis states. [Korzh, Fig. 1 and accompanying text; Fig. 3, Optics Express 21(17), pp. 19581, 19585 (2013)]. Thus, the feature that Applicant identified as absent from the former art is now directly taught in the QKD transmitter art itself.
Applicant argues that the former references do not teach the claimed electrical signal-manipulating units for controllable amplitude and/or delay adjustment. The present rejection does not rely on Kikawada's optical attenuators or Bunandar's optical delay lines for that limitation. Chen expressly teaches separate high-speed electrical driving signals and separate gain-control paths that controllably adjust the amplitudes of the electrical driving signals before electro-optic modulation. [Chen, US 2014/0205302 A1, Abstract; ¶¶ [0028]-[0030]]. Korzh independently teaches controllable electrical timing by synchronizing the RF pulses with an external variable RF delay. [Korzh, p. 19586]. Noguchi further confirms the ordinary electrical practice of providing separate amplitude-adjustment units 801-804 for respective driving-unit outputs. [Noguchi, US 2015/0110500 A1, ¶¶ [0080]-[0081]]. These are electrical, not optical, manipulations of the driving signals.
Applicant argues that the former Wang reference used a wired-AND arrangement in which only one generator was active and therefore did not teach electrical analog summation. The Office does not rely on that wired-AND arrangement in this Final Office Action. Chen expressly teaches an adder circuit that performs analogue summation of two separate electrical driving signals to obtain a four-level driving signal for an electro-optic phase modulator, including an embodiment in which P1 and P2 are summed before a gain-control network and an embodiment in which individually gain-controlled Pout1 and Pout2 are summed after gain control. [Chen, ¶¶ [0033]-[0034]; FIGS. 2A-2B]. The former wired-AND criticism therefore does not address the present ground.
Applicant further argues that the former art lacked a plurality of electrical analog combiner units and relied instead on optical combining. The present rejection uses electrical-combiner references for the electrical topology. Koontz expressly teaches a three-input RF power-combining method in which two electrical input signals are combined in a first transformer and the resulting first signal is then combined with the third input signal to produce the summed output. [Koontz, US 5,334,957, claim 30]. Knickerbocker likewise describes a conventional four-way binary electrical power combiner in which PA1/PA2 are combined by T1, PA3/PA4 are combined by T2, and the two intermediate outputs are combined by T3. [Knickerbocker et al., US 2008/0204134 A1, FIG. 3, Abstract, claim 1]. These references are relied upon only for the well-known electrical summing topologies; the QKD purpose and electro-optic use are supplied by Korzh, Chen, Tanaka and the other QKD/optical-modulator references identified below.
Applicant argues that the former rejection improperly equated Bunandar's optical constructive/destructive interference with opposite-polarity electrical combining. The present action does not make that equivalence. Korzh directly teaches positive and negative electrical RF pulses for QKD push-pull operation, Chen directly teaches electrical analogue summation used to drive an electro-optic modulator, and Koontz/Knickerbocker directly teach cascaded electrical combining. Bunandar is used only where its QKD state-generation, BB84, decoy-state, vacuum-state, or receiver-interferometer teachings are actually pertinent. Accordingly, the electrical architecture is no longer inferred from an optical-only architecture.
Applicant argues that the Office's previous rationale was conclusory and based on hindsight. The present grounds set forth the particular teaching supplied by each reference, the difference being addressed, and a claim-specific reason for the combination. The reasons arise from the references and the engineering problem, not from Applicant's disclosure: Korzh and Chen address high-speed QKD electrical drive generation for electro-optic modulation; Koontz and Knickerbocker teach established multi-input RF combining topologies; Noguchi teaches per-driver amplitude adjustment and optical-output feedback; Habif teaches a QKD power meter and power-responsive feedback controller; Tanaka teaches electrical multilevel drive for decoy-state QKD; and Zbinden teaches receiver-derived interference feedback over a public channel. Applying those known electrical drive and feedback techniques to the known QKD transmitters preserves their established functions and yields the predictable result of a controllable multi-level electrical drive waveform and calibrated QKD optical output. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007); MPEP § 2143.
Applicant specifically argues that claim 28 is patentable because the former references did not disclose four decoy states and because Bunandar discusses a commonly used two-decoy protocol. The Final Office Action relies additionally on Wang et al., Physical Review X 9, 021046 (2019), which expressly states that in decoy mode the intensity modulator randomly creates four decoy states with intensities μ, ν1, ν2, and ν3. [Wang et al., p. 021046-2]. Bunandar supplies the four BB84 states and an express vacuum decoy state. Thus, the asserted absence of four decoy states in the former combination is cured by direct prior-art disclosure rather than by an assumption that four is merely a predictable count.
Applicant argues that claims 3, 15, 43 and 44 remain patentable because Feng was only a generic driver and because the former references did not provide the claimed electrical source-and-combiner architecture. Feng is not necessary to the present grounds. For claim 3, Chen places an adjustable gain-control network in the electrical drive path, including after the adder in FIG. 2A. For claims 15 and 17, Korzh supplies opposite-polarity QKD electrical pulses, Noguchi supplies separate electrical driver adjustment and summing, Knickerbocker supplies the four-source/three-combiner binary tree, and Tanaka supplies electrical multilevel drive for signal/main and decoy-state QKD. Claims 43-45 are rejected on the method counterparts of those same concrete teachings. Applicant's argument against Feng therefore does not overcome the present grounds.
Applicant argues that the former five-reference combination spanned distinct sub-fields and that the motivation for adding Yuan was generic. The Final Office Action does not maintain the former Yuan-based combination. Each newly cited reference is used for a narrow, expressly identified feature reasonably pertinent to the electrical/QKD problem: electrical RF pulse generation and timing (Korzh), analogue electrical summation and gain (Chen), multi-input electrical combining topology (Koontz/Knickerbocker), per-driver amplitude control and optical-output feedback (Noguchi), literal QKD power measurement and power-responsive feedback (Habif), QKD main/decoy electrical modulation (Tanaka), decoy-state counts (Wang/Chau), and receiver interference feedback (Zbinden). The fact that more than one reference may be required to address a claim does not by itself establish nonobviousness. See In re Gorman, 933 F.2d 982, 986, 18 USPQ2d 1885, 1888 (Fed. Cir. 1991). The relevant inquiry is the combined teachings and the articulated reason to combine, not the number of references.
Applicant relies on MPEP 2142, MPEP 2143, Graham, and KSR and argues that the Office failed to establish a prima facie case. The present action applies those standards. For each ground below, the Office identifies the scope and content of the cited art, the differences from the amended claim, the particular known technique used to bridge the difference, the reason a person of ordinary skill would have applied that technique, and the predictable result/reasonable expectation of success. No objective evidence of nonobviousness has been identified in Applicant's August 25, 2026 response. Accordingly, Applicant's general prima-facie-case argument does not overcome the specific factual findings and rationales set forth below.
Claim Rejections - 35 U.S.C. § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all 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 and 2143, 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:
Determining the scope and contents of the prior art.
Ascertaining the differences between the prior art and the claims at issue.
Resolving the level of ordinary skill in the pertinent art.
Considering objective evidence present in the application indicating obviousness or nonobviousness.
The patent and non-patent publications relied upon below were publicly available before the January 5, 2022 claimed priority date. The printed publications Korzh et al. (2013), Wang et al. (2019), and Chau (2020) are applied as prior art under AIA 35 U.S.C. 102(a)(1). The cited U.S. patents and patent application publications were likewise publicly available before the claimed priority date and are relied upon under AIA 35 U.S.C. 102(a)(1).
Claims 1 and 3 are rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. (A High-Speed Multi-Protocol Quantum Key Distribution Transmitter Based on a Dual-Drive Modulator, Optics Express 21(17), 19579-19592 (2013)) in view of Chen et al. (US 2014/0205302 A1) and further in view of Koontz (US 5,334,957).
Claim 1
As per claim 1, Korzh provides the closest QKD electrical-transmitter foundation. Korzh discloses a high-speed QKD transmitter based on a dual-drive electro-optic modulator and an FPGA that drives two RF pulse-generator channels. The transmitter is explicitly demonstrated for BB84, COW and DPS protocols. [Korzh, Abstract; FIG. 1; pp. 19579-19582].
Korzh further teaches the claimed opposite-polarity electrical pulses. FIG. 3 expressly states that positive and negative electrical pulses in push-pull operation of the two DDM arms produce the QKD time-basis states, while the BB84 implementation uses both negative and positive drive levels. [Korzh, FIG. 3, p. 19585].
Thus, Korzh directly teaches a plurality of electrical pulse-signal channels in a QKD transmitter with one electrical pulse condition having polarity opposite another; this limitation is no longer inferred from optical interference.
Korzh also directly teaches controllable electrical timing. The RF pulses that drive the DDM are synchronized with an external variable RF delay before being amplified by two 12.5-GHz RF modulator drivers. [Korzh, p. 19586].
Thus, Korzh supplies a controllable electrical delay-time adjustment in the RF drive path.
For controllable electrical amplitude, Chen independently teaches separate gain-control paths for the two electrical driving signals P1 and P2, including attenuating and gain-amplifying units having fixed or adjustable gains. [Chen, ¶¶ [0028]-[0030]].
Korzh does not expressly describe its plurality of RF source-channel outputs as being analog-summed through plural cascaded electrical combiner units to form a single electrical light-modulating waveform. Chen supplies the direct electro-optic electrical-summation teaching. Chen is itself directed to high-speed QKD/BB84 phase modulation and teaches a high-speed serial transceiver that outputs two separate electrical driving signals, together with separate electrical gain control. [Chen, Abstract; ¶¶ [0004]-[0005], [0028]-[0030]].
Chen expressly teaches an adder circuit configured to perform analogue summation on the separate driving signals to obtain a four-level electrical driving signal for an electro-optic phase modulator. In FIG. 2A, adder circuit 2400 performs 2×P1+P2 and the summed signal is then passed through gain-control network 1200 to drive single-electrode electro-optic phase modulator 2300. In FIG. 2B, the individually gain-controlled Pout1 and Pout2 signals are summed by adder 2400' to form the four-level drive signal. [Chen, ¶¶ [0033]-[0034]; FIGS. 2A-2B].
Chen therefore teaches exactly the electrical, not optical, principle that Applicant argued was absent: separately generated electrical drive signals are adjusted and analog-summed, and the summed electrical signal is used as the light-modulating drive signal for an electro-optic modulator.
Koontz supplies the plural/cascaded electrical-combiner topology.
Koontz teaches a method of combining three RF input signals in which two of the three signals are first combined to provide a first summed signal and that first signal is then combined with the third input to provide the total output. [Koontz, claim 30].
Koontz also claims a three-port combiner having a first transformer connected between two inputs and a second transformer connected between the third input and the center tap of the first transformer. [Koontz, claims 16 and 23].
These are analog RF combining stages and establish that plural electrical combiner units arranged serially toward a common output were known well before Applicant's priority date.
It would have been obvious to a person of ordinary skill in the art to implement Korzh's plural high-speed QKD RF drive channels using Chen's analogue-summing EOM drive and, where more than two electrical channels are used, the known cascaded electrical combining topology of Koontz.
Korzh identifies the design objective of a compact, adaptable high-speed QKD transmitter; Chen teaches that analogue summation of separately generated electrical drive signals provides the multi-level voltage waveform required to drive an electro-optic phase modulator; and Koontz teaches the ordinary RF method for extending such summation to multiple source channels by staged combining. The modification would preserve the function of each element: the pulse sources still generate the QKD drive pulses, the gain/delay elements still set amplitude/timing, the combiners still sum electrical signals, and the electro-optic modulator still converts the resulting drive waveform into optical quantum states. The expected result - a controllable multi-level electrical QKD drive waveform formed from plural adjustable RF sources - would have been predictable with a reasonable expectation of success. See MPEP 2143, subsection I.A.
Accordingly, the combined teachings disclose or render obvious: (i) a QKD transmitter; (ii) a plurality of electrical pulse signal sources including opposite-polarity drive conditions; (iii) a plurality of electrical signal-manipulating stages controlling amplitude and/or delay; (iv) a plurality of analog electrical combining stages that combine source outputs; and (v) an electrical light-modulating signal proportional to the analog sum and used to modulate light into QKD states. Claim 1 is therefore unpatentable under 35 U.S.C. 103.
Claim 3
With respect to claim 3, all limitations of claim 1 are taught or rendered obvious by Korzh, Chen and Koontz as set forth above.
Claim 3 further requires an output tuneable gain unit configured to controllably adjust the electrical light-modulating signal before modulation.
Chen directly teaches this placement. In the FIG. 2A embodiment, the two electrical drive signals are first analog-summed by adder 2400 and the resulting four-level signal then enters gain-control network 1200 before driving electro-optic phase modulator 2300.
Chen explains that the gain-control network adjusts the driving-voltage output amplitude to adapt it to the phase modulator and may include attenuating and gain-amplifying units with fixed or adjustable gain. [Chen, ¶¶ [0028]-[0030], [0033]; FIG. 2A].
A person of ordinary skill would therefore have used Chen's adjustable post-summation gain network in the combined QKD transmitter for its expressly taught purpose of setting the modulation-drive amplitude supplied to the electro-optic modulator. This is the claimed output tuneable gain unit and would have yielded the predictable result of controllable overall modulation depth. Claim 3 is therefore obvious.
Claims 4 and 6 are rejected under 35 U.S.C. § 103 as being unpatentable over Korzh et al. in view of Chen et al. and Koontz, as applied to claim 1 above, and further in view of Noguchi (US 2015/0110500 A1).
Claim 4
With respect to claim 4, the combination applied to claim 1 already teaches a multi-source QKD electrical drive with adjustable electrical signals and cascaded electrical combining. Claim 4 specifies three electrical pulse signal sources, respective three electrical signal-manipulating units, and two electrical analog combiner units.
Koontz expressly teaches three RF inputs and staged combining: two of the three input signals are combined first, and the resulting signal is combined with the third signal to form the final output. [Koontz, claim 30]. This directly supplies the three-source/two-stage-combining organization.
Noguchi expressly teaches four electrical driving units 501-504 and four respective amplitude-adjustment units 801-804. Each adjustment unit receives the output of its respective driving unit and independently adjusts that electrical signal amplitude using coefficient K1-K4; the adjusted signals are then summed by adding units 1400a/1400b. [Noguchi, ¶¶ [0080]-[0081]; FIG. 11].
This directly teaches at least three independently generated electrical drive channels, each with its own electrical manipulation unit.
Combining three such channels with Koontz's known three-input/two-stage RF summing topology provides the three electrical pulse sources, three respective manipulation units, and two electrical combiner units recited by claim 4, with the predictable summed electrical output. Claim 4 is therefore obvious.
Claim 6
With respect to claim 6, all limitations of claim 4 are taught or rendered obvious as set forth above. Claim 6 now requires the specific serial arrangement in which a first analog combiner combines the second and third source signals, those sources having opposite polarities, and a second analog combiner combines the first-combiner output with the first source signal.
Koontz claim 30 expressly recites the same electrical combining order at the functional level: first combine two of three RF inputs to form a first summed signal, then combine the third RF input with that first signal to provide the overall output.
Korzh expressly teaches the QKD use of positive and negative electrical drive pulses. [Korzh, FIG. 3].
Accordingly, using the opposite-polarity pair as the first pair entering Koontz's first combining stage and then adding the remaining QKD drive source in the next stage is no more than applying the known three-input binary-tree combiner to the known QKD RF signals.
The reason to use this ordering is not hindsight.
Koontz expressly teaches the three-input RF problem and the two-stage solution: combine two RF inputs to obtain an intermediate sum and then combine the remaining RF input with that intermediate signal to obtain the total output.
Applying that same known two-stage RF architecture to the Korzh/Chen high-speed electrical modulator drive performs the same established combining function and predictably yields the summed electrical light-modulating waveform.
Claim 6 is therefore obvious.
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al., Koontz and Noguchi, as applied to claim 4 above, and further in view of Bunandar et al. (US 2016/0352515 A1).
Claim 5
Claim 5 further requires that, for at least one main quantum state, the electrical pulse signals from the source having the opposite voltage polarity are not combined with electrical pulse signals from the other sources.
Bunandar expressly teaches state-dependent use of source paths in QKD: Z-basis main states are prepared using one ring resonator/source path, whereas X-basis states use both ring resonators to form superposition/interference states. [Bunandar, ¶¶ [0050]-[0051]].
Once the electrical multi-source architecture of Korzh/Chen/Koontz/Noguchi is used, Bunandar provides an express QKD reason to activate only one available source branch for at least one main state while using multiple branches for other states.
A person of ordinary skill would therefore have operated the opposite-polarity source branch by itself for at least one single-bin main state, leaving the other electrical source branches inactive so that the opposite-polarity pulse signal is not combined with signals from the other sources. The result is the predictable electrical implementation of Bunandar's known state-dependent single-path versus multi-path QKD state generation. Claim 5 is therefore obvious.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al., Koontz and Noguchi, as applied to claim 6 above, and further in view of Tanaka et al. (US 2007/0248362 A1).
Claim 8
Claim 8 is drafted in the alternative and is satisfied when the QKD transmitter is configured for at least one of the listed amplitude-setting operations. It is therefore not necessary for a single embodiment of the prior art to perform every alternative recited in claim 8.
Tanaka is directed to a QKD system using electrical multilevel signals RF1 and RF2 to drive a dual-electrode Mach-Zehnder modulator for simultaneous phase and intensity modulation. [Tanaka, Abstract; ¶¶ [0058]-[0060]].
Tanaka expressly teaches opposite-phase electrical RF1/RF2 drive levels and, in the QKD embodiment, explains that a relative RF1/RF2 voltage difference of Vπ/2 reduces the optical intensity by one half.
Tanaka further teaches multilevel electrical drive and reduced-intensity decoy states. [Tanaka, ¶¶ [0075], [0081], [0088], [0109]-[0113]].
The combined transmitter already contains independent electrical amplitude-adjustment stages.
Applying Tanaka's expressly taught one-half optical-intensity target to the adjustable P1/P2 electrical drive pair would have predictably produced at least the final alternative of claim 8, in which the intensity responsive to the second and third electrical pulse signals is adjusted to about one half of the upper-mid-level intensity. Noguchi expressly teaches independently adjustable amplitudes for the driver outputs, providing the known control mechanism for reaching that target.
Claim 8 is therefore obvious.
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al., Koontz and Noguchi, as applied to claim 6 above.
Claim 13
Claim 13 is likewise drafted as “at least one of the following” delay-minimization alternatives. Korzh expressly provides an external variable RF delay for synchronizing the RF pulses that drive the DDM. [Korzh, p. 19586].
Korzh further teaches the calibration relationship used to set that electrical timing: high extinction is desirable, and the transmitter output power is monitored as a function of relative delay while the timing of a short pulse is scanned against a fixed QKD pattern. [Korzh, pp. 19586-19587].
Thus the prior art expressly links relative timing adjustment to the measured optical-output minimum/extinction condition used for QKD calibration.
In the combined transmitter, Korzh's variable RF delay is an electrical source-path adjustment, and the known output-intensity measurement provides the calibration objective.
A person of ordinary skill would have used the disclosed variable RF delay to scan the relative timing of the relevant electrical pulse pair until residual optical output for the destructive/empty condition was minimized, because that is the same delay-versus-output calibration Korzh uses to obtain high extinction. The adjustment uses the known variable-delay element for its established purpose and has a predictable response. At least one delay-minimization alternative of claim 13 would therefore have been obvious.
Claim 30 is rejected under 35 U.S.C. § 103 as being unpatentable over Korzh et al. in view of Chen et al. and Koontz, as applied to claim 1 above, and further in view of Noguchi and Habif et al. (US 2011/0280405 A1).
Claim 30
With respect to claim 30, all limitations of claim 1 are taught or rendered obvious by Korzh, Chen and Koontz. Claim 30 further requires: (i) an output tuneable gain unit configured to controllably adjust the electrical light-modulating signal before modulation; (ii) a power meter configured to measure optical output power/intensity and generate measurement data/signals; and (iii) a control unit configured to adjust at least one electrical signal-manipulating unit and/or the output tuneable gain unit based on the measurement data/signals.
Chen directly teaches limitation (i). In the FIG. 2A embodiment, adder 2400 first forms the multi-level electrical sum and the resulting signal then passes through gain-control network 1200 before driving electro-optic phase modulator 2300; the gain-control network includes attenuating and gain-amplifying units with adjustable gain. [Chen, ¶¶ [0028]-[0030], [0033]; FIG. 2A].
Habif directly teaches the literal power-measurement feedback of limitation (ii): QKD transmitter 900 includes power meter 906, which measures the intensity of calibration light after traversal of the transmitter interferometer and produces a detected-power signal; the transmitter controller receives the detected power signal and generates feedback for controlling transmitter operation. [Habif, ¶¶ [0054], [0057]-[0059]; FIG. 9].
Noguchi independently teaches limitation (iii) at the electrical-drive level: output-light intensity is detected and control circuitry uses the detected intensity to determine electrical threshold voltages supplied to the driving units. [Noguchi, ¶¶ [0059]-[0064]; claim 5; FIG. 6].
A person of ordinary skill would have had a clear reason to combine these known feedback teachings with the Korzh/Chen transmitter: Chen already provides an adjustable post-summation electrical gain stage, Habif shows that a QKD transmitter uses measured optical power to generate feedback, and Noguchi shows that measured output intensity is used to alter electrical drive parameters. Applying the measurement signal to the already-present electrical manipulation/gain controls would predictably maintain the desired QKD optical output and compensate drift. Claim 30 is therefore obvious.
Claim 33 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al. and further in view of Noguchi.
Claim 33
As per claim 33, Korzh teaches calibration and operation of a QKD transmitter using plural electrical RF pulse channels, including positive and negative electrical pulse conditions, electrical timing control, amplification, and an electro-optic dual-drive modulator that generates QKD states. [Korzh, FIGS. 1 and 3; pp. 19581, 19585-19587].
Chen teaches generating separate high-speed electrical drive signals, controllably adjusting their amplitudes through gain-control circuitry, analog-summing the electrical signals, and driving an electro-optic modulator with the resulting multi-level electrical signal. [Chen, Abstract; ¶¶ [0028]-[0034]; FIGS. 1, 2A-2B].
These teachings map the steps of generating the electrical pulses, combining them to form the electrical light-modulating signal, and modulating light with that signal.
Noguchi supplies the measurement-and-feedback calibration step.
Noguchi detects the intensity of modulated output light with detection unit 1100, generates a detection signal representative of that intensity, and determines/controls electrical threshold voltages for the driving units on the basis of the detected output intensity so that the optical output reaches a desired value. [Noguchi, ¶¶ [0036]-[0039], ¶¶ [0059]-[0064]; claim 5].
Noguchi also teaches independent amplitude-adjustment units 801-804 for the electrical driving-unit outputs. [Noguchi, ¶¶ [0080]-[0081]].
It would have been obvious to apply Noguchi's known optical-output feedback calibration to Korzh/Chen's QKD electrical drive because electro-optic modulator output depends on the applied electrical amplitude and relative timing, and both references seek stable, accurately generated optical modulation states.
The modification would simply measure the already-generated modulated light and tune the existing gain/delay settings until the desired state/output condition is reached. The result - a calibrated QKD transmitter - is the expected result of the known feedback technique.
Claim 33 is therefore obvious.
Claims 34 and 36 are rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al. and Noguchi, as applied to claim 33 above, and further in view of Bunandar et al.
Claim 34
Claim 34 further specifies three electrical pulse signals for generation of the electrical light-modulating signal and at least one main quantum state generated without combining the opposite-polarity source with the other electrical pulses.
Noguchi teaches four independently driven electrical channels and expressly states that outputs of a plurality of driving units may be amplitude-adjusted and summed by adding units; using three such channels provides the recited first, second and third electrical pulse signals. [Noguchi, ¶¶ [0067]-[0071], [0080]-[0081]].
Bunandar expressly teaches that some QKD main states use one source path while other QKD states use multiple source paths: Z-basis states may be prepared using one ring resonator, whereas X-basis states use both ring resonators. [Bunandar, ¶¶ [0050]-[0051]].
Applying Bunandar's known state-dependent channel selection to the already-obvious electrical three-channel drive would have led one of ordinary skill to operate a single source branch alone for at least one main state, so that the opposite-polarity source signal is not simultaneously combined with the other electrical pulse signals.
Claim 34 is therefore obvious.
Claim 36
Claim 36 is drafted as “at least one of the following” and therefore is met when any one listed amplitude- or delay-adjustment alternative is rendered obvious. The final two alternatives require adjustment of relative electrical-pulse timing until optical output responsive to the selected pulse pair is minimized.
Korzh expressly teaches an external variable RF delay for the QKD electrical drive and measures transmitter output power as a function of relative timing while seeking high extinction. [Korzh, pp. 19586-19587].
Applying that disclosed delay scan to the relevant P0/P1 or P1/P2 electrical pulse pair in the method of claims 33-34 would predictably identify the timing setting at which residual modulated-light power is minimized. This uses the known variable RF delay for the same QKD extinction-calibration purpose taught by Korzh.
Accordingly, at least one of the delay-minimization alternatives recited by claim 36 would have been obvious, and claim 36 is rejected.
Claims 15 and 17 are rejected under 35 U.S.C. § 103 as being unpatentable over Korzh et al. in view of Chen et al. and Koontz, as applied to claim 1 above, and further in view of Noguchi, Knickerbocker et al. (US 2008/0204134 A1), and Tanaka et al.
Claim 15
Claim 15 requires four electrical pulse sources arranged as two opposite-polarity pairs, respective signal-manipulating units, three electrical analog combiner units, with one pair assigned to main quantum states and the other pair assigned to decoy states.
Korzh directly teaches a QKD opposite-polarity electrical pair: positive and negative electrical pulses in push-pull DDM operation generate QKD states. [Korzh, FIG. 3].
Chen teaches QKD electrical gain control and analog summation for an electro-optic modulator. [Chen, ¶¶ [0028]-[0034]]. Noguchi expressly teaches four electrical driving units 501-504 with four respective amplitude-adjustment units 801-804, and then sums the adjusted driver outputs in adding units. [Noguchi, ¶¶ [0080]-[0081]; FIG. 11].
Thus, the four-source architecture has a known respective electrical manipulation stage for each source branch.
Knickerbocker establishes the exact four-input/three-combiner binary-tree topology as conventional electrical practice. Its FIG. 3 has four separate power-amplifier sources PA1-PA4; PA1/PA2 are combined by transformer T1, PA3/PA4 are combined by transformer T2, and the two intermediate outputs are combined at transformer T3. [Knickerbocker, FIG. 3 and accompanying description; Abstract; claim 1].
The reference expressly describes this as a conventional four-way binary power combiner well known to those skilled in the art. The reference is relied upon for the electrical combining topology, not for QKD protocol operation.
Tanaka supplies the QKD main/decoy electrical-drive purpose.
Tanaka teaches a QKD transmitter using multilevel electrical RF1/RF2 signals to a Mach-Zehnder modulator so that both phase and intensity are controlled, and expressly identifies reduced optical-intensity levels as decoy-state pulses while the higher level is used for the signal state. [Tanaka, ¶¶ [0062]-[0066], ¶ [0088], ¶¶ [0107]-[0113]].
A person of ordinary skill seeking independently controllable main and decoy electrical waveforms would have had a clear reason to use two instances of Korzh's known complementary/push-pull electrical pair: one pair assigned to the known main/signal drive class and one pair assigned to the known reduced-intensity decoy class taught by Tanaka. Noguchi shows that four electrical drive branches can each be independently amplitude-adjusted, and Knickerbocker shows the conventional four-input/three-combiner electrical tree for reducing those four branches to one output.
Chen confirms that electrical amplitude control and analog summation are ordinary EOM-drive techniques. Each duplicated pair performs the same established complementary-drive function, while the main/decoy assignment provides the predictable benefit of independent calibration of the two known QKD intensity classes.
The resulting four adjusted electrical sources and three combiners therefore would have been a predictable implementation of known circuitry, not a reconstruction based on Applicant's disclosure.
Claim 15 is therefore obvious.
Claim 17
Claim 17 is expressly drafted as “configured for at least one of the following.” The first listed architecture requires a first combiner for P3/P2, a second combiner combining that result with P1, and a third combiner combining the second-combiner output with P0. It is sufficient for the prior art to render obvious this one alternative; every subsequent optional amplitude/delay alternative need not also be present in the same embodiment.
Knickerbocker teaches four electrical sources and three electrical combining stages in a conventional four-way power-combiner network. [Knickerbocker, FIG. 3; claim 1].
Koontz independently teaches cascaded electrical combining in which a first combiner combines two input signals and a later combining stage adds a further input to the already-combined signal to obtain the sum of the inputs. [Koontz, US 5,334,957, claims 16, 23 and 30].
Thus, the combined art expressly supplies the ingredients of the particular claim-17 topology: four independently adjustable electrical source branches (Noguchi), three electrical combining stages for four sources (Knickerbocker), and serial/cascaded addition of an additional source to an intermediate combined signal (Koontz).
A person of ordinary skill implementing four independently controlled QKD electrical sources would have had a reason to use the cascaded two-input arrangement recited in claim 17 - first combine P3/P2, then add P1, then add P0 - because cascading ordinary two-input RF combiners is a standard way to reduce a plurality of source branches to one summed output while preserving the independent amplitude/timing control of each branch.
Korzh supplies the QKD opposite-polarity drive requirement.
Tanaka supplies the main/decoy intensity allocation; Noguchi supplies the respective electrical manipulation units; and Knickerbocker/Koontz supply the established electrical combining implementation. This rationale does not depend on relabeling a different tree as the claimed circuit.
Koontz's expressly taught cascaded-addition principle successively to the four independently controlled branches already made conventional by the other references. The expected result is the summed RF waveform used to drive the modulator.
Accordingly, at least the recited three-combiner alternative of claim 17 would have been obvious and claim 17 is rejected.
Claims 43, 44 and 45 are rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al. and Noguchi, as applied to claim 33 above, and further in view of Knickerbocker et al. and Tanaka et al.
Claim 43
Claim 43 is the method counterpart of the two-pair electrical architecture. Korzh teaches QKD generation with positive and negative electrical pulses in a complementary push-pull pair; Chen teaches analog summation of electrical drive signals for an electro-optic modulator; Noguchi teaches four independently adjustable electrical driver outputs; Knickerbocker teaches four electrical sources combined in two pairwise first-stage combiners and then a final combiner; and Tanaka supplies the known main/signal and reduced decoy electrical-drive classes. [Korzh, FIG. 3; Chen, ¶¶ [0033]-[0034]; Noguchi, ¶¶ [0080]-[0081]; Knickerbocker, FIG. 3, claim 1; Tanaka, ¶¶ [0088], [0107]-[0113]].
It would have been obvious to perform, in method form, the ordinary operation of that combined transmitter: use two instances of the known complementary electrical pair so the known main and decoy drive classes are independently controllable, combine the four adjusted electrical signals through the known pairwise combining tree, and use the resulting electrical waveform for QKD modulation. Each element performs its established function and the method produces the predictable operation of the known combined apparatus.
The method does not require a new function beyond the predictable operation of the known apparatus. Claim 43 is therefore obvious.
Claim 44
Claim 44 additionally assigns main quantum states to one pair and decoy states to the other. Tanaka expressly teaches electrically generated QKD signal/main and decoy intensity classes using multilevel RF drive to a Mach-Zehnder modulator. [Tanaka, ¶¶ [0088], [0107]-[0113]]. Given two independently controllable complementary electrical pairs, assigning one to the main-state voltage/intensity settings and the other to the reduced decoy settings is a direct functional partition of the known Tanaka state classes. The partition provides the predictable benefit of independent calibration and does not alter either pair's electrical function.
Claim 44 is therefore obvious.
Claim 45
Claim 45, like claims 8 and 36, requires “at least one of the following” listed calibration operations. It is sufficient to render one listed alternative obvious.
Korzh expressly teaches variable electrical RF timing and measures QKD transmitter output power as a function of relative delay while seeking high extinction. [Korzh, pp. 19586-19587]. Noguchi supplies four independently adjustable electrical driver branches in the four-channel architecture. [Noguchi, ¶¶ [0080]-[0081]].
A person of ordinary skill would have applied the same disclosed RF-delay scan to the relevant P0/P1, P1/P2, or P2/P3 pair until residual modulated-light power was minimized, because that is the same known timing-to-extinction calibration used by Korzh.
At least one delay-minimization alternative of claim 45 therefore would have been the predictable calibration of the known four-channel transmitter. Claim 45 is obvious.
Claim 28 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al. and Koontz, as applied to claim 1 above, and further in view of Wang et al. (Beating the Fundamental Rate-Distance Limit in a Proof-of-Principle Quantum Key Distribution System, Physical Review X 9, 021046 (2019)) and Bunandar et al.
Claim 28
Claim 28 adds four main quantum states, four decoy states, and one vacuum state. Korzh expressly implements BB84, whose four time/phase basis states are shown in the QKD coding scheme of FIG. 3. [Korzh, FIG. 3].
Bunandar independently states that Alice and Bob prepare photon signals in one of the four BB84 states and teaches that a decoy state can be vacuum. [Bunandar, ¶ [0003], ¶ [0084]].
Most importantly in view of Applicant's argument,
Wang et al. expressly disclose four decoy states.
Wang states that, in decoy mode, IM3 “randomly creates four decoy states with μ, ν1, ν2, and ν3 photons per pulse.” [Wang et al., Physical Review X 9, 021046, p. 021046-2 (2019)]. This is a direct disclosure of the exact decoy-state count Applicant argued was absent from the former art.
A person of ordinary skill would have applied Wang's expressly demonstrated four-decoy protocol and Bunandar's vacuum class to the known adjustable QKD transmitter because the transmitter already has electrically controllable intensity settings and the state count is implemented by selecting known drive/intensity values.
No change in operating principle is required; the expected result is transmission of the known BB84 main states together with the expressly known four-decoy schedule and vacuum.
Claim 28 is therefore obvious.
Claim 29 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al., Koontz and Noguchi, as applied to claim 4 above, and further in view of Chau (Security of Finite-Key-Length Measurement-Device-Independent Quantum Key Distribution Using an Arbitrary Number of Decoys, Physical Review A 102, 012611 (2020)).
Claim 29
Claim 29 requires four main quantum states, any number of decoy states, and one vacuum state. Korzh provides the four-state BB84 QKD operation.
Chau is expressly directed to MDI-QKD using an arbitrary number of decoys and reports a security proof that works for any fixed number of decoy states. [Chau, title and Abstract, Physical Review A 102, 012611 (2020)].
Chau further expressly treats an intensity of zero and defines yield conditioned on Alice preparing a vacuum state. [Chau, Sec. II].
Thus, “any number of decoy states” and use of a vacuum state were not new transmitter principles but recognized protocol choices before Applicant's priority date. Applying Chau's arbitrary fixed decoy count to the electrically adjustable QKD transmitter would merely select how many known intensity settings are used, with the same expected modulation function. Claim 29 is therefore obvious.
Claim 32 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al. and Koontz, as applied to claim 1 above, and further in view of Zbinden (US 2009/0010435 A1).
Claim 32
Claim 32, as amended, requires receiver-originated feedback over a standard communication channel, the feedback indicating an interference-visibility measure obtained through an unbalanced receiver interferometer in response to an optical signal pattern sent over the quantum channel, and transmitter adjustment of clock frequency and/or pulse time difference based on that feedback.
Zbinden directly teaches the receiver/feedback architecture. Its interferometric quantum-cryptography system has an emitter station and a receiver station communicating through a quantum channel and a public/conventional communication channel. [Zbinden, Abstract; ¶¶ [0037]-[0042]; FIG. 4].
In the DPS embodiment, the receiver bit-analysis subsystem includes an imbalanced interferometer with a path-length difference corresponding to the separation of adjacent pulses and single-photon detectors at the output. [Zbinden, ¶ [0041]].
Zbinden further teaches that the emitter processing unit obtains information collaboratively with the receiver processing unit and uses it to estimate interference contrast and determine whether tuning is required. The information may be derived from ordinary bit-carrying pulses or from dummy pulses periodically inserted specifically to gather interference-contrast information.
The emitter then gathers the receiver-derived contrast information, applies a maximization algorithm, transmits the new adjustment value to the emitter controller, adjusts the transmitter, and loops. [Zbinden, ¶¶ [0043]-[0050]; FIG. 5].
This directly supplies a standard/public feedback channel, a receiver interferometer/detector, a transmitted calibration pattern, receiver-derived interference information, and a closed adjustment loop at the transmitter.
Korzh supplies the specific clock/timing parameter recited by claim 32.
Korzh explains that the transmitter can generate almost any time delay using electronic control and is adaptable to receivers having different interferometer imbalances. [Korzh, p. 19586].
Korzh further states that the receiver interferometer frequency response can be analyzed and the transmitter frequency adapted to the optimum; it experimentally measures visibility as a function of frequency and selects the transmitter operating/clock frequency near 1.25 GHz at maximum visibility. [Korzh, FIG. 4 and accompanying text, pp. 19586-19587].
It would have been obvious to use Zbinden's standard/public receiver-feedback loop to communicate the interference-quality measurement used by Korzh to tune the transmitter clock or RF timing. Both references address the same recognized problem - maintaining interference quality in a QKD link when transmitter timing and receiver interferometer characteristics must remain matched.
Zbinden provides the communications/feedback mechanism; Korzh provides the exact transmitter parameters and visibility optimization. Combining them would have predictably automated a calibration Korzh already performs and would have had a reasonable expectation of success.
Claim 32 is therefore obvious.
Claim 54 is rejected under 35 U.S.C. 103 as being unpatentable over Korzh et al. in view of Chen et al. and Noguchi, as applied to claim 33 above, and further in view of Zbinden.
Claim 54
Claim 54 is the method-form counterpart of the receiver-feedback calibration and expressly recites transmitting an optical signal pattern over the quantum channel, receiving the pattern at the QKD receiver, determining an interference-visibility measure with the receiver's unbalanced interferometer, sending feedback over a standard communication channel, receiving the feedback at the transmitter, and adjusting transmitter clock frequency and/or electrical pulse time difference.
Zbinden expressly teaches the operational sequence of transmitting ordinary or dummy optical pulses through the quantum channel, measuring them at an imbalanced receiver interferometer, deriving interference-contrast information from receiver detection events, communicating between receiver and emitter over the public channel, calculating a parameter adjustment, adjusting the emitter, and repeating the loop. [Zbinden, ¶¶ [0037]-[0050]; FIGS. 4-5].
Korzh expressly teaches the complementary method step of changing QKD transmitter timing/frequency according to receiver interferometer performance: it electronically controls time delay, measures receiver/interferometer visibility as a function of transmitter frequency, and selects the clock frequency at the visibility optimum. [Korzh, pp. 19586-19587; FIG. 4]. Noguchi confirms the general calibration practice of generating optical measurement data and changing electrical drive conditions to obtain a desired optical output. [Noguchi, ¶¶ [0059]-[0064]].
A person of ordinary skill would therefore have implemented Korzh's visibility-based clock/timing optimization through Zbinden's expressly disclosed receiver-to-emitter public feedback loop. The modification simply automates known measurement and tuning steps and yields the expected result of maintaining high interference visibility despite timing/interferometer variation.
Claim 54 is therefore obvious.
It is noted that citations to specific pages, columns, paragraphs, lines, claims, or figures in the prior-art references are provided to identify particularly relevant disclosures and should not be understood as limiting the references to only those passages. 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
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Mohammed Abdelraheem, whose telephone number is (571) 272-0656. The examiner can normally be reached Monday–Thursday.
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/MOHAMMED ABDELRAHEEM/Examiner, Art Unit 2635
/DAVID C PAYNE/Supervisory Patent Examiner, Art Unit 2635
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