DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Response to Amendment
Claims 1-20 are pending. Claims 1-3, 8-10, 12, 15-19 stand amended.
Response to Arguments
Applicant's arguments filed 3/16/2026 have been fully considered but they are not persuasive. Applicant asserts that because Srinivas drives the trapping and control electrodes using control frequencies, the entanglement operation occurs based on non-magnetic fields. However, as detailed below with respect to Srinivas, the oscillating magnetic field gradients form the basis for entanglement. That electric fields are present (as they must be in view of, e.g. Maxwell, but also for ion movements e.g. rotations per Srinivas) is not considered to imply that the qubit entanglement mechanism is based on the electric field. Indeed, Srinivas appears drawn entirely to avoiding entanglement operations based on the electric field (p. 209, “Individual laser-free addressing can be achieved using spatial gradients of magnetic or electric fields … However, the highest-fidelity laser-free entangling interactions so far have approximately three to five times larger corrected Bell-state infidelities than the laser-based interactions in refs. 5–7 and are more than an order of magnitude slower.”; then goes on to discuss magnetic field gradient entanglement improvement at length).
Therefore Applicant’s arguments with respect to Srinivas’ disclosure of the amended claims are not found persuasive, and the rejections are maintained with respect to the independent claims.
However, Srinivas does not disclose the method of claim 1, wherein the two or more quantum objects are entangled within the magnetic field gradient zone during the gate time period without use of any radiating fields to mediate the entanglement of the two or more quantum objects and the two or more quantum objects stop experiencing the magnetic field gradient such that a spin-motion entanglement of the two or more quantum objects is adiabatically eliminated, and is considered to constitute allowable subject matter as detailed below.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(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.
Claims 1-17, 19, and 20 rejected under 35 U.S.C. 102(a)(1) as being anticipated by Srinivas (High-fidelity laser-free universal control of trapped ion qubits1, newly cited2).
Regarding claim 1 and 15, directed to corresponding method and system similarly amended, Srinivas teaches a method for performing a geometric phase gate (p. 210, C. 1, ¶1 – C. 2, ll. 1, choosing a frequency offset δ between magnetic fields “… to implement a geometric phase gate, entangling the
ion states via their shared motion …”), the method comprising:
controlling, by a controller (p. 210, C. 1, ¶1, “The entangling operation relies on control signals …”), operation of a confinement apparatus (Fig. 1, “Trapping Electrodes”) to cause two or more quantum objects (Fig. 1, pair of Magnesium ions along the trap axis) confined by the confinement apparatus and disposed in a magnetic field gradient zone of the confinement apparatus to experience a magnetic field gradient (p. 210, C. 1, ¶1, “A strong magnetic field gradient … is combined with two additional weaker microwave magnetic fields, symmetrically detuned by δ from the qubit frequency ∼ω0 ≈ 2π × 1.326 GHz, which is shifted from its nominal value of ω0 by residual magnetic fields oscillating at ωg.”); and
responsive to determining that a gate time period has elapsed (that is, achieving entanglement by the geometric phase gate) with at least one of
(a) the two or more quantum objects disposed within the magnetic field gradient zone (Fig. 1) or
(b) the two or more quantum objects experiencing the magnetic field gradient (Fig. 1),
controlling, by the controller, operation of the confinement apparatus to cause the two or more quantum objects to stop experiencing the magnetic field gradient (p. 210, C. 2, ¶3, discussing the geometric phase gate for entanglement operation: “This entire operation has a total duration of 740 μs”, and so the end of the magnetic gate operation is implicit; see also Supplemental Information, “The currents at ωg and ˜ω0 ± δ are ramped up and down smoothly over 5µs, with rising and falling edges following an approximate sine-squared envelope. Due to the size of the ac Zeeman shift ∆ac, the drive at ωg is ramped up completely before the microwave currents at ˜ω0 ±δ are ramped up, and the downward ramps are carried out in reverse order. The π/2 and π pulses at ω0 are carried out when all the other currents are turned off, so the qubit frequency is not ac Zeeman-shifted and the qubit is not driven off-resonantly. The phases of these pulses, denoted with subscripts x and y, where y indicates a 90◦ phase shift with respect to x, are chosen to provide robustness to miscalibrations (overrotation or underrotation) in the π pulses. The total duration of the entangling operation is 740 µs, of which the up and down ramps (during which relatively little entanglement is generated) consume 160 µs.” and Fig. S2, “We plot the amplitude of the control signals schematically versus time.”),
wherein experiencing the magnetic field gradient causes entanglement of the two or more quantum objects (Abstract, “We use a scheme based on radiofrequency magnetic field gradients combined with microwave magnetic fields that is robust against multiple sources of decoherence and usable with essentially any trapped ion species.”), the entanglement between the two or more quantum objects is enacted solely by the magnetic field gradient (p. 211, “We generate this entangling operation by applying the gradient and microwave fields as shown in Fig. 1a, using a sequence of eight pulses of simultaneously applied radiofrequency and microwave currents, interleaved with five qubit π pulses, and a π/2 pulse at the beginning and end of the sequence (Supplementary Fig. 2).”), and the magnetic field gradient is a gradient of a near field portion of a magnetic field (sequitur Fig. 1, the trap and control fields are experienced by the ions 30 microns above the electrodes).
Regarding claim 3 and 4, Srinivas teaches the method of claim 1, and further discloses wherein the magnetic field gradient oscillates with a frequency that is less than a motional frequency of a motional modes of the two or more quantum objects (as discussed above 740 microseconds for the entire entanglement gate operation to occur; p. 210, “A strong magnetic field gradient with amplitude 152(15) T m−1 oscillating at frequency ωg = 2π × 5 MHz, close to the frequency ωr of one of the ions’ out-of-phase radial (transverse to the trap axis) motional modes at ωr ≈ 2π × 6.9 MHz”, ωg < ωr”; Abstract, “In trapped-ion systems, the entangling interactions required for universal control typically rely on an effective qubit–qubit coupling mediated by the shared motion of the ions25–29. Realizing this coupling requires control fields at the ions’ positions that have strong spatial gradients on the length scale of the ions’ zero-point motion (usually a few nanometres)” and in light of Fig. 1 where red detuning is explicitly shown relative to the motional mode frequency, the instant claim’s requirement is considered disclosed).
Regarding claim 5, Srinivas teaches the method of claim 1, and further discloses further comprising causing respective quantum states of the two or more quantum objects to be evolved to respective gate subspace states (p. 210, ¶2, “We use the |F = 3, mf = 3⟩ ≡ ↓⟩ and |F = 2, mf = 2⟩ ≡ ↑⟩ states within the ions’ 2S1/2 ground-state hyperfine manifolds as our qubit states, where F is the total angular momentum and mF is its projection along the quantization axis defined by a 21.3 mT static magnetic field.”).
Regarding claim 6, Srinivas teaches the method of claim 5, and further discloses wherein the respective quantum states are evolved out of a memory subspace and into a gate subspace, wherein the respective gate subspace states are respective states of the gate subspace (p. 210, ¶2, “We use the |F = 3, mf = 3⟩ ≡ ↓⟩ and |F = 2, mf = 2⟩ ≡ ↑⟩ states within the ions’ 2S1/2 ground-state hyperfine manifolds as our qubit states, where F is the total angular momentum and mF is its projection along the quantization axis defined by a 21.3 mT static magnetic field.”, considering the disclosed operation into hyperfine manifold, i.e. gate subspace, as the claimed evolution; see Srinivas’s Supplementary Information, reproduced entirely for convenience: “The value of |B0| was chosen to provide a first-order magnetic-field-insensitive qubit transition between the states |↓` > ≡ 2S1/2 |F = 3, mF = 1 > and |↑` > ≡ 2S1/2 |F = 2, mF = 1> … Such field-insensitive qubits can have measured coherence times of many seconds or even minutes. When not performing entangling gates, we could map the populations in |↓i and |↑i into the state |↓0 i and |↑0 i using microwave control pulses, allowing the qubit state to be stored coherently for much longer times than is possible in the {|↓i, |↑i} qubit.”).
Regarding claim 7, Srinivas teaches the method of claim 6, and further disclose wherein the memory subspace comprises two or more memory states that are each a respective clock state (per Applicant’s specification, ¶115, the memory states are clock states, which initial states are magnetic field insensitive, therefore see Srinivas’s Supplemental Information, very first paragraph, “The value of |B0| was chosen to provide a firstorder magnetic-field-insensitive qubit transition between the states … ) and the gate subspace comprises two or more gate subspace states that are each Zeeman states (Fig. 1’s description, the gated ions experiencing distinct AC Zeeman shifts).
Regarding claim 8, Srinivas teaches the method of claim 5, and further discloses (Supplemental Information, II. FIELDS AND GRADIENTS FOR ENTANGLING INTERACTION) wherein evolving the respective quantum states to the respective gate subspace states comprises causing a manipulation signal (magnetic field) characterized by a frequency (“The microwave fields are characterized by the corresponding resonant Rabi frequency”) that is substantially resonant with the frequency difference between at least one memory subspace state and a corresponding gate subspace state to be incident on at least one of the two or more quantum objects (definitionally of the Rabi frequency, lest the disclosed geometric phase gate operation not occur at all).
Regarding claim 9 and 10, Srinivas teaches the method of claim 5, and further discloses wherein causing the two or more quantum objects to stop experiencing the magnetic field gradient comprises: evolving the respective quantum states of the two or more quantum objects from the respective gate subspace states to respective memory states (Supplemental Information, “When not performing entangling gate” i.e. in the absence of the gradient mediated entangling geometric phase gate, “we could map the populations in |↓>and |↑> into the state |↓` > and |↑` > using microwave control pulses, allowing the qubit state to be stored coherently for much longer times than is possible in the {|↓>, |↑>} qubit."; see equation S3, defining the resonant Rabi frequency of the manipulating signal for the state transition).
Regarding claim 11, Srinivas teaches the method of claim 1, and further discloses further comprising, performing one or more dynamic decoupling sequences on at least one quantum object of the two or more quantum objects between an initiation of the gate time period and a completion of the gate time period (p. 210, “By tuning the amplitude Ωμ”, i.e. the Rabi frequency, “of the two microwave fields to an appropriate value (an ‘intrinsic dynamical decoupling’ or ‘IDD’ point), the qubits are dynamically decoupled from dephasing noise at frequencies well below δ, without requiring any additional control fields”).
Regarding claim 12, Srinivas teaches the method of claim 11, and further discloses wherein performing the one or more dynamic decoupling sequences on the at least one quantum objects of the two or more quantum objects comprises causing a dynamic decoupling manipulation signal to be incident on the at least one quantum object (p. 210, “… the qubits are dynamically decoupled from dephasing noise at frequencies well below δ, without requiring any additional control fields”).
Regarding claim 13, Srinivas teaches the method of claim 1, and further discloses wherein: the magnetic field gradient is turned on in the magnetic field gradient zone at least one of (a) while the two or more quantum objects are being transported into the magnetic field gradient zone or (b) while the two or more quantum objects are disposed within the magnetic field gradient zone (Fig. 1), and the magnetic field gradient is turned off in the magnetic field gradient zone at least one of (a) while the two or more quantum objects are being transported out of the magnetic field gradient zone, (b) while the two or more quantum objects are disposed within the magnetic field gradient zone (Fig. 1), or (c) after the two or more quantum objects are transported out of the magnetic field gradient zone.
Regarding claim 14, Srinivas teaches the method of claim 1, and further discloses wherein one of (a) the magnetic field gradient is a static magnetic field gradient and is substantially constant over the gate time period (Fig. 1, p. 210, specifically noting that strong static magnetic field gradients have been used in the past in laser free entanglement demonstrations) or (b) the magnetic field gradient oscillates during the gate time period with a frequency that is less than a motional mode frequency of a motional mode of a respective quantum object of the two or more quantum objects (Fig. 1, p. 210, “A strong magnetic field gradient with amplitude 152(15) T m−1 oscillating at frequency ωg = 2π × 5 MHz, close to the frequency ωr of one of the ions’ out-of-phase radial (transverse to the trap axis) motional modes at ωr ≈ 2π × 6.9 MHz”).
Regarding claim 16, Srinivas teaches the system of claim 15, and further discloses wherein the confinement apparatus comprises or is associated with at least one of (a) at least one permanent magnet or (b) at least one electromagnet configured to cause the magnetic field gradient to be present in the at least one magnetic field gradient zone (Fig. 1, p. 210, “… whereas the confining potential is created by oscillating and static voltages applied to the purple and grey trapping electrodes, respectively”, “with radiofrequency and microwave control currents, as well as trapping voltages, applied to electroplated gold electrodes on a surface-electrode trap as shown in Fig. 1b”).
Regarding claim 17, Srinivas teaches the system of claim 15, and further discloses wherein the confinement apparatus defines a plurality of magnetic field gradient zones, comprising the at least one magnetic field gradient zone (p. 212, “Multiple trapping zones in a multizone ion trap”), and the two or more quantum objects comprise a plurality of pairs of quantum objects (sequitur, a pair for each trap as in Fig. 1) and the controller is configured to cause each of the plurality of pairs of quantum objects to be transported into and out of respective magnetic field gradient zones of the plurality of magnetic field gradient zones substantially simultaneously (p. 212, “This technology offers potential advantages for scaling of trapped-ion quantum processors by enabling entangling operations to be carried out simultaneously in multiple trapping zones in a multizone ion trap, as the control currents can produce the necessary gradients and fields in multiple zones at the same time. The entanglement of any particular group of ions could be enabled simply by adjusting the trap confinement in that zone with static potentials applied to local trapping electrodes, shifting the motional mode frequency of each zone in or out of resonance with the entangling interaction … These features may enable a new large-scale, multizone ion-trap quantum computing architecture using a two-ion-species qubit/helper design, where all qubit operations aside from ion loading are carried out with radiofrequency or microwave signals, along with microwatt-scale laser beams for the helper species.”).
Regarding claim 19, Srinivas teaches a method for performing a geometric phase gate, the method comprising: causing, by a controller of a quantum system (p. 210, C. 1, ¶1, “The entangling operation relies on control signals …”), two or more qubits of the quantum system to experience a magnetic field gradient (Fig. 1, pair of Magnesium ions along the trap axis, and p. 210, C. 1, ¶1, “A strong magnetic field gradient … is combined with two additional weaker microwave magnetic fields, symmetrically detuned by δ from the qubit frequency ∼ω0 ≈ 2π × 1.326 GHz, which is shifted from its nominal value of ω0 by residual magnetic fields oscillating at ωg.”); and
responsive to determining that a gate time period has elapsed since the two or more qubits of the quantum system started to experience the magnetic field gradient, causing, by the controller, the two or more qubits to no longer experience the magnetic field gradient (p. 210, C. 2, ¶3, discussing the geometric phase gate for entanglement operation: “This entire operation has a total duration of 740 μs”; see also Supplemental Information, “The currents at ωg and ˜ω0 ± δ are ramped up and down smoothly over 5µs, with rising and falling edges following an approximate sine-squared envelope. Due to the size of the ac Zeeman shift ∆ac, the drive at ωg is ramped up completely before the microwave currents at ˜ω0 ±δ are ramped up, and the downward ramps are carried out in reverse order. The π/2 and π pulses at ω0 are carried out when all the other currents are turned off, so the qubit frequency is not acZeeman-shifted and the qubit is not driven off-resonantly. The phases of these pulses, denoted with subscripts x and y, where y indicates a 90◦ phase shift with respect to x, are chosen to provide robustness to miscalibrations(overrotation or underrotation) in the π pulses. The total duration of the entangling operation is 740 µs, of which the up and down ramps (during which relatively little entanglement is generated) consume 160 µs.” and Fig. S2, “We plot the amplitude of the control signals schematically versus time.”),
wherein experiencing the magnetic field gradient causes entanglement of the two or more quantum objects (Abstract, “We use a scheme based on radiofrequency magnetic field gradients combined with microwave magnetic fields that is robust against multiple sources of decoherence and usable with essentially any trapped ion species.”), the entanglement between the two or more quantum objects is enacted solely by the magnetic field gradient (p. 211, “We generate this entangling operation by applying the gradient and microwave fields as shown in Fig. 1a, using a sequence of eight pulses of simultaneously applied radiofrequency and microwave currents, interleaved with five qubit π pulses, and a π/2 pulse at the beginning and end of the sequence (Supplementary Fig. 2).”), and the magnetic field gradient is a gradient of a near field portion of a magnetic field (sequitur Fig. 1, the trap and control fields are experienced by the ions 30 microns above the electrodes).
Regarding claim 20, Srinivas teaches the method of claim 19, and further discloses wherein the gate time period is determined based at least in part on an amount of time it takes for the magnetic field gradient to mediate the entanglement of the two or more qubits (p. 210, C. 2, ¶3, discussing the geometric phase gate for entanglement operation: “This entire operation has a total duration of 740 μs”).
Claim Rejections - 35 USC § 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 of this title, 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.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents 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.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
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 any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 18 is rejected under 35 U.S.C. 103 as being unpatentable over Srinivas as applied to claim 15 above, and further in view of Srinivas #2 (High-fidelity rf/microwave-based universal control of trapped ion qubits, of record).
Regarding claim 18, Srinivas teaches the system of claim 15, wherein the confinement apparatus defines at least one radiating field zone that is spatially distinct from the at least one magnetic field gradient zone (p. 210, “These features may enable a new large-scale, multizone ion-trap quantum computing architecture using a two-ion-species qubit/helper design, where all qubit operations aside from ion loading are carried out with radiofrequency or microwave signals, along with microwatt-scale laser beams for the helper species. These laser beams could be delivered efficiently to all zones using integrated optics”; it is considered that the radiating field must necessarily be spatially distinct in order to assist with ion loading from outside the gradient zone to inside the gradient zone).
Srinivas does not explicitly show the controller is further configured to, prior to causing transportation of the two or more quantum objects into the at least one magnetic field gradient zone, causing a respective quantum states of at least one quantum object of the two or more quantum objects to be evolved to a respective gate subspace state while the at least one quantum object is disposed within the at least one radiating field zone.
However, Srinivas #2 explicitly shows an analogous system of magnetic universal control of trapped ion qubits, and specifically indicates that it is known in the art to move quantum objects into and out of radiating fields, thus causing a respective quantum states of at least one quantum object of the two or more quantum objects to be evolved to a respective gate subspace state while the at least one quantum object is disposed within the at least one radiating field zone (p. 80, C. 1, ¶1, “Individual addressing for laser-based universal control has been demonstrated using … by moving individual ions into and out of laser beams.”; quantum objects in the gate subspace being plainly necessary for universal control). Srinivas #2 provides a similar statement concerning the use of laser beams specifically for cooling and readout (p. 82, C. 2, last paragraph, “These features may enable a new large-scale, parallelized, multi-zone ion trap quantum computing architecture using a two-ion-species qubit/helper design, in which all qubit operations aside from ion loading are carried out solely with rf and microwave signals, along with microwatt-scale laser beams for the helper species for laser cooling and fluorescence readout. Such low-power laser beams could be delivered to all zones using trap-integrated photonic waveguides”).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have employed laser beams in a predictable fashion known to Srinivasa before the effective filing date of the claimed invention, e.g. for the purpose of reading out the quantum information, thus realizing a functioning quantum computing apparatus.
Allowable Subject Matter
Claim 2 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Conclusion
THIS ACTION IS MADE FINAL. 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.
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/COLLIN X BEATTY/Primary Examiner, Art Unit 2872
1 Srinivas R ET AL: "High-fidelity laser-free universal control of two trapped ion qubits". Nature | Vol 597 | 9 September 2021. https://doi.org/10.1038/s41586-021-03809-4 (Year: 2021)
2 Important note that this document corresponds to the full print Nature publication, which may differ significantly from the preprint cited by Applicant’s 3/8/2024 Information Disclosure Statement
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