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 .
Election/Restrictions
Applicant’s election without traverse of claim 12 in the reply filed on 9/16/2026 is acknowledged. Claims 10 and 11 are withdrawn from consideration.
Note on Prior Art and Claim Objection
Claim 9 is objected for being dependent on rejected claim 1. The prior art of record does not teach or make obvious claim 9, “the third surface code stabilizer is measured in parallel to the fourth surface code stabilizer and subsequent to the first surface code stabilizer and the second surface code stabilizer.” In fact, Surface code for low-density qubit array by Tomaru et al us p. 2 says, “The stabilizer measurements shown in Fig. 1b and c are performed for all stabilizers simultaneously and repeatedly.” It is unclear why it would be obvious to add a reference that teaches a drawn out sequential measure of qubits. This same idea is missing from the prior art with respect to claim 12, where “measuring the XXXX stabilizer and the ZZZZ stabilizer comprises:
performing a first CNOT gate on a first measure qubit and a first data qubit, wherein the first measure qubit acts as a control;
performing a second CNOT gate on a second data qubit and a third data qubit, wherein the second data qubit acts as a control;…”
Claim Rejections - 35 USC § 112
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 12 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Applicant recites, “wherein the data qubit in the plurality of qubits is either the first, second, third, or fourth data qubit the first measure qubit is a measure qubit for the XXXX stabilizer…” (emphasis added). Maybe there is supposed to be a comma in there, like, the fourth data qubit, the first measure qubit is a measure qubit for the XXXX stabilizer.
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, 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.
Claims 1-3, 5-8 and 13-15 are rejected under 35 U.S.C. 103 as being unpatentable over Surface code for low-density qubit array by Tomaru et al and US20210125094A1 to Chamberland et al.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Surface code for low-density qubit array by Tomaru et al, US20210125094A1 to Chamberland et al and Surface code compilation via edge-disjoint paths to Beverland et al.
Tomaru teaches claim 1. A method for performing a surface code cycle using a quantum computer comprising a plurality of qubits, the method comprising:
for a data qubit in the plurality of qubits that is coupled to three measure qubits in the plurality of qubits, wherein the data qubit is coupled to a first measure qubit by a first qubit coupler, a second measure qubit by a second qubit coupler, and a third measure qubit by a third qubit coupler; (Tomaru fig. 1 “Schematic surface code. (a) Open circles show data qubits with information; solid circles show syndrome qubits that are ancillas. Data qubits interact with syndrome qubits through green and yellow edges.” See below. The ancillas are the measure qubits. The green and yellow edges are the couplers.)
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measuring a first surface code stabilizer, comprising performing a first set of entangling operations between the data qubit and the first measure qubit using the first qubit coupler;
measuring a second surface code stabilizer, comprising performing a second set of entangling operations between the data qubit and the second measure qubit using the second qubit coupler;
measuring a third surface code stabilizer, comprising performing a third set of entangling operations between the data qubit and the third measure qubit using the third qubit coupler; and (All three stabilizers are taught by Tomaru p. 1, Tomaru p. 7 and Tomarue Fig. 1. Tomaru p. 1 “One group of edge qubits works as deputies of the data qubits; the other group works as deputies of the syndrome qubits. The stabilizer measurements are performed using CNOT operations between the data qubits and deputy syndrome qubits and between the deputy data qubits and syndrome qubits, instead of between the data and syndrome qubits in ordinary surface code.” CNOT gates are entangling operations. Nature p. 7 “A data qubit interacts with four syndrome qubits through a CNOT during one round of stabilizer measurements in the ordinary surface code.”)
Tomaru doesn’t teach remeasuring the second qubit as a fourth measurement.
However, Chamberland teaches measuring a fourth surface code stabilizer, comprising performing a fourth set of entangling operations between the data qubit and the second measure qubit using the second qubit coupler. (Chamberland fig. 5b below and para 72 “the second stabilizer component 402 can map two flag qubit vertices (e.g., represented by white circles) corresponding the numbered flag qubits of the fourth stabilizer measurement circuit 504 to positions on the exemplary trivalent lattice 200 and within the defined hexagon region in accordance with the various embodiments described herein. In addition, each of the two flag qubit vertices are connected to two data qubit vertices based on the connectivity of the fourth stabilizer measurement circuit 504.” The connection between the black data qubit and the measurement qubits 2 and 4.)
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Tomaru, Chamberland and the claims are all directed to surface code. It would have been obvious to a person having ordinary skill in the art, at the time of filing, to reuse a coupler in order to because Tomaru abstract advocates for a “surface code [t] operate on sparse qubit arrays” and Chamberland para teaches how to reduce connectivity because “reducing a degree of connectivity between ancilla and data qubits can minimize frequency collisions and/or crosstalk errors.”
Tomaru teaches claim 2. The method of claim 1, wherein the first surface code stabilizer, the second surface code stabilizer, the third surface code stabilizer, and the fourth surface code stabilizer comprise ZZZZ or XXXX stabilizers. (Tomaru p. 2 “Each syndrome qubit is surrounded by four data qubits that compose a stabilizer, except for boundaries. … The stabilizers are πi ˆ Zi and πj ˆ Xj… ˆ Zs1 ≡ ˆ Z2 ˆ Z3 ˆ Z10 ˆ Z11 and ˆ Xs2 ≡ ˆ X3 ˆ X7 ˆ X10 ˆ X12 by referring to Fig. 1a.” Z and X hat are the vectors representing measurement vectors (like ZZZZ or XXXX) for the data qubits i.)
Tomaru teaches claim 3. The method of claim 1, wherein the first, second, third, and fourth set of entangling operations comprise CNOT operations. (All three stabilizers are taught by Tomaru p. 1, Tomaru p. 7 and Tomarue Fig. 1. Tomaru p. 1 “One group of edge qubits works as deputies of the data qubits; the other group works as deputies of the syndrome qubits. The stabilizer measurements are performed using CNOT operations…”)
Tomaru teaches claim 4. The method of claim 1, wherein the first, second, third, and fourth set of entangling operations comprise CNOT operations and (All three stabilizers are taught by Tomaru p. 1, Tomaru p. 7 and Tomarue Fig. 1. Tomaru p. 1 “One group of edge qubits works as deputies of the data qubits; the other group works as deputies of the syndrome qubits. The stabilizer measurements are performed using CNOT operations…”)
Tomaru doesn’t teach SWAP gates.
However, Beverland teaches SWAP gates. (Beverland p. 28 “Before each set of gates, a permutation built from swap-gates is applied…”)
Beverland, Tomaru and the claims are all directed to surface code. It would have been obvious to a person having ordinary skill in the art, at the time of filing, to use swap gates “so that the gates in the set can be applied locally.” Beverland p. 28.
Chamberland teaches claim 5. The method of claim 1, wherein the plurality of qubits is arranged as a hexagonal grid. (Chamberland fig. 5b below and para 72 “the second stabilizer component 402 can map two flag qubit vertices … within the defined hexagon region in accordance with the various embodiments described herein.”)
Tomaru teaches claim 6. The method of claim 1, wherein the plurality of qubits is arranged as a square grid. (Tomaru fig. 1 below)
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Tomaru teaches claim 7. The method of claim 1, wherein the data qubit comprises a bulk data qubit. (Tomaru p. 7 “A data qubit interacts with four syndrome qubits through a CNOT…” Interaction with four syndrome qubits makes the data qubit a bulk data qubit.)
Tomaru teaches claim 8. The method of claim 1, wherein the first surface code stabilizer is measured in parallel to the second surface code stabilizer. (Tomaru p. 2 “. The stabilizer measurements shown in Fig. 1b and c are performed for all stabilizers simultaneously and repeatedly.” Simultaneous performance is parallel measurement.)
Tomaru teaches claim 13. A quantum computing apparatus comprising:
a plurality of physical qubits; (Tomaru fig. 1)
qubit couplers defining nearest neighbor interactions between the plurality of qubits; and; (Tomaru fig. 1 “Data qubits interact with syndrome qubits through green and yellow edges.” The adjacent coupling through edges is nearest neighbor interactions.)
control electronics configured to operate the plurality of qubits and qubit couplers, wherein the control electronics are configured to perform operations for implementing a surface code cycle, the operations comprising: (Tomaru fig. 1 “Schematic surface code. (a) Open circles show data qubits with information; solid circles show syndrome qubits that are ancillas. Data qubits interact with syndrome qubits through green and yellow edges.”)
for a data qubit in the plurality of qubits that is coupled to three measure qubits in the plurality of qubits, wherein the data qubit is coupled to a first measure qubit by a first qubit coupler, a second measure qubit by a second qubit coupler, and a third measure qubit by a third qubit coupler; (Tomaru fig. 1 “Schematic surface code. (a) Open circles show data qubits with information; solid circles show syndrome qubits that are ancillas. Data qubits interact with syndrome qubits through green and yellow edges.” See below. The ancillas are the measure qubits. The green and yellow edges are the couplers.)
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measuring a first surface code stabilizer, comprising performing a first set of entangling operations between the data qubit and the first measure qubit using the first qubit coupler;
measuring a second surface code stabilizer, comprising performing a second set of entangling operations between the data qubit and the second measure qubit using the second qubit coupler;
measuring a third surface code stabilizer, comprising performing a third set of entangling operations between the data qubit and the third measure qubit using the third qubit coupler; and (All three stabilizers are taught by Tomaru p. 1, Tomaru p. 7 and Tomarue Fig. 1. Tomaru p. 1 “One group of edge qubits works as deputies of the data qubits; the other group works as deputies of the syndrome qubits. The stabilizer measurements are performed using CNOT operations between the data qubits and deputy syndrome qubits and between the deputy data qubits and syndrome qubits, instead of between the data and syndrome qubits in ordinary surface code.” CNOT gates are entangling operations. Nature p. 7 “A data qubit interacts with four syndrome qubits through a CNOT during one round of stabilizer measurements in the ordinary surface code.”)
Tomaru doesn’t teach remeasuring the second qubit as a fourth measurement.
However, Chamberland teaches measuring a fourth surface code stabilizer, comprising performing a fourth set of entangling operations between the data qubit and the second measure qubit using the second qubit coupler. (Chamberland fig. 5b below and para 72 “the second stabilizer component 402 can map two flag qubit vertices (e.g., represented by white circles) corresponding the numbered flag qubits of the fourth stabilizer measurement circuit 504 to positions on the exemplary trivalent lattice 200 and within the defined hexagon region in accordance with the various embodiments described herein. In addition, each of the two flag qubit vertices are connected to two data qubit vertices based on the connectivity of the fourth stabilizer measurement circuit 504.” The connection between the black data qubit and the measurement qubits 2 and 4.)
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Tomaru, Chamberland and the claims are all directed to surface code. It would have been obvious to a person having ordinary skill in the art, at the time of filing, to reuse a coupler in order to because Tomaru abstract advocates for a “surface code [t] operate on sparse qubit arrays” and Chamberland para teaches how to reduce connectivity because “reducing a degree of connectivity between ancilla and data qubits can minimize frequency collisions and/or crosstalk errors.”
Tomaru teaches claim 14. A method for performing a surface code cycle, the method comprising:
for a quantum computer comprising an array qubits (Tomaru fig. 1 “Schematic surface code. (a) Open circles show data qubits with information; solid circles show syndrome qubits that are ancillas. Data qubits interact with syndrome qubits through green and yellow edges.” See below. The ancillas are the measure qubits. The green and yellow edges are the couplers.)
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measuring a first column of alternating XXXX and ZZZZ stabilizers in the array of qubits; (Tomaru fig. 1 above shows the x stabilizers in yellow above and the z stabilizers in green above. Both stabilizers are in their own columns.)
measuring a second column of alternating XXXX and ZZZZ stabilizers in the array of qubits, wherein the second column is adjacent to the first column and the XXXX and ZZZZ stabilizer measurements in the second column vertically mirror the XXXX and ZZZZ stabilizer measurements in the first column. (Tomaru fig. 1 above shows the x stabilizers in yellow above and the z stabilizers in green above. Both stabilizers are in their own columns.)
Tomaru doesn’t teach the max of three other qubits.
However, Chamberland teaches wherein each qubit in the array of qubits is coupled to at most three other qubits. (Chamberland para 51 “a trivalent lattice such that ancilla qubits and/or data qubits of the given quantum circuit can have degree three connectivity.”)
Tomaru, Chamberland and the claims are all directed to surface code. It would have been obvious to a person having ordinary skill in the art, at the time of filing, to reuse a coupler in order to because Tomaru abstract advocates for a “surface code [t] operate on sparse qubit arrays” and Chamberland para teaches how to reduce connectivity because “reducing a degree of connectivity between ancilla and data qubits can minimize frequency collisions and/or crosstalk errors.” Using an even more sparse design like the trivalent lattice increases sparsity.
Tomaru teaches claim 15. A quantum computing apparatus comprising:
a plurality of physical qubits; (Tomaru fig. 1)
qubit couplers defining nearest neighbor interactions between the plurality of qubits; and (Tomaru fig. 1 “Data qubits interact with syndrome qubits through green and yellow edges.” The adjacent coupling through edges is nearest neighbor interactions.)
control electronics configured to operate the plurality of qubits and qubit couplers, wherein the control electronics are configured to perform operations for implementing a surface code cycle, the operations comprising: (Tomaru fig. 1 “Schematic surface code. (a) Open circles show data qubits with information; solid circles show syndrome qubits that are ancillas. Data qubits interact with syndrome qubits through green and yellow edges.”)
for a quantum computer comprising an array qubits, wherein each qubit in the array of qubits is coupled to (Tomaru fig. 1 “Schematic surface code. (a) Open circles show data qubits with information; solid circles show syndrome qubits that are ancillas. Data qubits interact with syndrome qubits through green and yellow edges.” See below. The ancillas are the measure qubits. The green and yellow edges are the couplers.)
measuring a first column of alternating XXXX and ZZZZ stabilizers in the array of qubits; (Tomaru fig. 1 above shows the x stabilizers in yellow above and the z stabilizers in green above. Both stabilizers are in their own columns.)
measuring a second column of alternating XXXX and ZZZZ stabilizers in the array of qubits, wherein the second column is adjacent to the first column and the XXXX and ZZZZ stabilizer measurements in the second column vertically mirror the XXXX and ZZZZ stabilizer measurements in the first column. (Tomaru fig. 1 above shows the x stabilizers in yellow above and the z stabilizers in green above. Both stabilizers are in their own columns.)
Tomaru doesn’t teach the max of three other qubits.
However, Chamberland teaches qubits is coupled to (Chamberland para 51 “a trivalent lattice such that ancilla qubits and/or data qubits of the given quantum circuit can have degree three connectivity.”)
Tomaru, Chamberland and the claims are all directed to surface code. It would have been obvious to a person having ordinary skill in the art, at the time of filing, to reuse a coupler in order to because Tomaru abstract advocates for a “surface code [t] operate on sparse qubit arrays” and Chamberland para teaches how to reduce connectivity because “reducing a degree of connectivity between ancilla and data qubits can minimize frequency collisions and/or crosstalk errors.” Using an even more sparse design like the trivalent lattice increases sparsity.
Conclusion
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/AUSTIN HICKS/Primary Examiner, Art Unit 2142
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