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 .
Information Disclosure Statement
Acknowledgment is made of the information disclosure statements filed on 21 October 2025, U.S. patents and Foreign Patents have been considered.
Claim Rejections - 35 USC § 103
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.
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, 4 – 7, 9 – 14, 16, and 18 are rejected under 35 U.S.C. 103 as being unpatentable over US11070210B2 (Reagor) in view of US20100148853A1 (Harris) and further in view of US20130278283A1 (Berkley).
In regards to claim 1 (Reagor) shows a detector for reading out a state of a data qubit, the detector comprising:
a flux qubit; Reagor [Column 7 Lines 1 - 15] teaches a qubit device that includes circuit elements forming a flux qubit.
a flux bias generator, wherein the flux qubit comprises an inductor, a SQUID loop comprising at least one Josephson junction; Reagor [Column 7 Lines 35 - 45] teaches a control system that functions as a flux bias generator to tune qubit frequency. Reagor [Column 7 Lines 1 - 15] teaches a qubit comprising an inductor and first and second Josephson junctions forming a SQUID loop.
and a capacitor, wherein the capacitor comprises a first capacitor pad on a first side of the SQUID loop and a second capacitor pad on a second side of the SQUID loop, wherein the first capacitor pad is connected to the inductor by a first wire, and the second capacitor pad is connected to the inductor by a second wire; Reagor [Column 7 Lines 1 - 15] teaches a physical capacitor implemented as capacitor pads formed of superconducting material on the substrate. Reagor [Column 6 Lines 40 - 55] teaches the capacitor connected in parallel with the inductor between a first circuit node and a second circuit node on opposite sides of the SQUID loop, the connections between devices being formed by superconducting wire.
wherein the inductor, the SQUID loop and the capacitor are connected to each other in parallel; Reagor [Column 6 Lines 40 - 55] teaches the inductor connected between circuit nodes, the first Josephson junction connected in parallel with the inductor between the nodes, the second Josephson junction connected in parallel with the inductor between the nodes, and the capacitor connected in parallel with the inductor.
wherein the flux bias generator is configured to generate a first flux bias through the inductor and a second flux bias through the SQUID loop; Reagor [Column 7 Lines 35 - 45] teaches a control system that tunes qubit frequency by controlling flux bias device current levels to deliver specific fluxes to different parts of the circuit.
wherein the flux bias generator is configured to, in the following order; Reagor [Column 5 Lines 60 - 65] teaches controlling magnetic flux received by circuit loops of the qubit device in specific operational sequences, allowing precise execution of quantum operations in a predetermined order.
and a resonance frequency of the flux qubit is tuned to a frequency of interaction such that the flux qubit is coupled to the data qubit and the state of the data qubit is mapped to an energy state of the flux qubit; Reagor [Column 11 Lines 1 - 10] teaches modifying external magnetic fluxes to tune the qubit frequency for coupling operations with another qubit, enabling information transfer between the coupled qubits.
Reagor differs from the claimed invention in that it does not explicitly disclose a measurement unit; wherein the flux qubit is arranged to exhibit a first flux state and a second flux state; wherein the flux qubit is configured such that, in response to a first value of the first flux bias, the energies of the first and the second flux states are substantially identical and such that, in response to a second value of the first flux bias, the energies of the first and the second flux states are different; wherein, in response to a first value of the second flux bias, the flux qubit is configured to be coupled to the data qubit and, in response to a second value of the second flux bias, to be decoupled from the data qubit and to suppress tunneling between the first and the second flux states.
Harris teaches wherein the flux qubit is arranged to exhibit a first flux state and a second flux state; Harris [0063] teaches an rf-SQUID flux qubit whose two distinct states are the two directions of circulating current, corresponding to a left potential well and a right potential well of a bistable double-well potential.
Harris teaches wherein the flux qubit is configured such that, in response to a first value of the first flux bias, the energies of the first and the second flux states are substantially identical and such that, in response to a second value of the first flux bias, the energies of the first and the second flux states are different; Harris [0063] teaches the two potential minima can be degenerate, meaning they have the same energy, and Harris [0065] and [0074] teach that adjusting the magnetic flux applied to the loop raises the potential minimum of one well relative to the other so the energies of the two flux states are made different.
Harris teaches wherein, in response to a first value of the second flux bias, the flux qubit is configured to be coupled to the data qubit and, in response to a second value of the second flux bias, to be decoupled from the data qubit and to suppress tunneling between the first and the second flux states; Harris [0084] teaches lowering the tunneling barrier and turning on a coupling to the other qubit so the state is transferred, and Harris [0087] teaches raising the tunneling barrier to prevent tunneling between the wells and removing the coupling to decouple the qubit.
Harris teaches generate the first value of the first flux bias, such that the energies of the first and the second flux states of the flux qubit are substantially identical; Harris [0063] and [0083] teach biasing the qubit so the bistable potential has two degenerate wells of substantially identical energy.
Harris teaches generate the first value of the second flux bias, such that a barrier between the first flux state and the second flux state is minimized; Harris [0084] teaches adiabatically reducing the height of the energy barrier to zero or near zero by tuning the flux through the split-junction (SQUID) loop, bringing the qubit into the quantum regime.
Harris teaches generate the second value of the first flux bias, such that the energies of the first and the second flux states of the flux qubit are different; Harris [0074] teaches raising the potential minimum of one well relative to the other by tuning the magnetic flux through the superconducting loop, so the bistable potential has a shallow well and a deep well of different energies.
Harris teaches generate the second value of the second flux bias, such that the flux qubit is decoupled from the data qubit and the energy state of the flux qubit is mapped to a superposition of the first flux state or the second flux state; Harris [0087] teaches adiabatically raising the energy barrier to lock the qubit into one of the two wells and removing the coupling, so the qubit is decoupled from the other qubit and its energy state is mapped into the flux states.
Harris differs from the claimed invention in that it does not explicitly disclose a measurement unit; and wherein the measurement unit is configured to determine whether the flux qubit is in the first flux state or the second flux state and to output a signal in dependence on whether the flux qubit is in the first flux state or in the second flux state.
Berkley teaches a measurement unit; Berkley [0044] teaches a readout circuit comprising a variable transformer circuit having a DC-SQUID inductively coupled to the qubit loop.
Berkley teaches wherein the measurement unit is configured to determine whether the flux qubit is in the first flux state or the second flux state and to output a signal in dependence on whether the flux qubit is in the first flux state or in the second flux state; Berkley [0047] and [0048] teach that the transmitted power through the variable transformer circuit produces a first output voltage corresponding to the 0 state of the qubit and a second output voltage corresponding to the 1 state, thereby distinguishing the flux states and outputting a signal dependent on the state.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to provide the flux qubit with a controllable bistable double-well potential, enabling reliable preparation and locking of distinct flux states, with a reasonable expectation of success as both references address superconducting flux qubits.
It would have been obvious to one of ordinary skill in the art to further combine Reagor, Harris, and Berkley to determine and output the resulting flux state of the qubit using a non-dissipative DC-SQUID readout circuit, with a reasonable expectation of success as the references address superconducting qubit readout.
In regards to claim 4 (Reagor) shows the detector of claim 1:
wherein in response to the first value of the second flux bias, the flux qubit is configured to be coupled to the data qubit by tuning a resonance frequency of the flux qubit into resonance of a resonance frequency of the data qubit; Reagor [Column 14 Lines 45 - 55] teaches two-qubit operations realized by tuning the qubit frequency of one qubit device towards the qubit frequency of a second qubit device, creating the coupling for quantum information exchange.
In regards to claim 5 (Reagor) shows the detector of claim 4:
wherein in response to the second value of the second flux bias, the resonance frequency of the flux qubit differs from the resonance frequency of the data qubit by more than 2 GHz; Reagor [Column 14 Lines 45 - 55] teaches parking the first qubit at a frequency far from the second qubit’s frequency, specifically 1 GHz or more, as an example of sufficient frequency difference for decoupling the qubits.
In regards to claim 6 (Reagor) shows the detector of claim 1:
wherein the measurement unit comprises: a signal generator; a transmission line; and a power detector; Reagor [Column 14 Lines 1 - 10] teaches a measurement system with a microwave source that generates signals, transmission components that deliver the signals, and a readout system that detects response signals and functions as a power detector.
wherein the flux qubit is connected to the transmission line via a shunt line, wherein the signal generator is configured to send travelling waves to the power detector via the flux qubit through the transmission line; Reagor [Column 15 Lines 40 - 50] teaches a signal port connected to a resonator drive line extending to a readout resonator, and a qubit drive line connecting the readout resonator to the qubit device, allowing signals to travel from external systems through the transmission components to the qubit and back.
wherein the measurement unit is configured to determine whether the flux qubit is in the first flux state or in the second flux state based on an output of the power detector; Reagor [Column 14 Lines 10 - 20] teaches that the readout response signal contains information about the quantum state of the qubit device, with detectable frequency, phase, or amplitude shifts indicating the state of the qubit.
In regards to claim 7 (Reagor) shows the detector of claim 6:
wherein the measurement unit does not comprise a circulator, a parametric amplifier, and a high electron mobility transistor HEMT; Reagor [Column 14 Lines 1 - 10] teaches a readout system using a microwave source and readout resonator to detect qubit states through direct signal paths and capacitive coupling, demonstrating a measurement approach that functions without requiring circulators, parametric amplifiers, or HEMTs.
In regards to claim 9 (Reagor) shows the detector of claim 1:
wherein a capacitance of the capacitor is between 10fF to 100fF; Reagor [Column 18 Lines 60 - Column 19 Lines 20] teaches a charging energy EC of 3 GHz for the capacitor, which corresponds to a capacitance in the range of 25 to 30 fF as is standard in the field of superconducting qubits, falling within the claimed range of 10fF to 100fF.
In regards to claim 10 (Reagor) does not show the detector of claim 1: wherein an area occupied by the SQUID loop is between 1 µm2 to 100 µm2.
Harris teaches wherein an area occupied by the SQUID loop is between 1 µm2 to 100 µm2; Harris [0098] teaches that the qubit loop area may be between about 5 µm2 and 100000 µm2, an overlapping range that renders obvious the claimed range of 1 µm2 to 100 µm2.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to select a micrometer-scale SQUID loop area providing appropriate inductance for reliable flux qubit operation, with a reasonable expectation of success as both references address superconducting flux qubits.
In regards to claim 11 (Reagor) does not show the detector of claim 1: wherein the flux qubit is arranged such that, in response to the first value of the second flux bias, a potential barrier is formed between the first flux state and the second flux state such that the tunneling between the first flux state and the second flux state is reduced.
Harris teaches wherein the flux qubit is arranged such that, in response to the first value of the second flux bias, a potential barrier is formed between the first flux state and the second flux state such that the tunneling between the first flux state and the second flux state is reduced; Harris [0064] and [0065] teach that the height of the energy barrier between the two potential wells is set by tuning the Josephson energy via the flux through the split-junction loop, and that a higher barrier reduces tunneling between the wells.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to control the potential barrier between flux states, improving state stability and readout fidelity, with a reasonable expectation of success as both references address superconducting flux qubits.
In regards to claim 12 (Reagor) does not show the detector of claim 1: wherein the flux qubit is arranged such that, in response to the second value of the first flux bias, the difference in the energies of the first flux state and the second flux state is generated.
Harris teaches wherein the flux qubit is arranged such that, in response to the second value of the first flux bias, the difference in the energies of the first flux state and the second flux state is generated; Harris [0074] teaches that adjusting the magnetic flux through the superconducting loop raises the potential minimum of one well relative to the other, generating a difference in the energies of the two flux states.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to tilt the potential energy landscape so the two flux states are energetically distinguishable for readout, with a reasonable expectation of success as both references address superconducting flux qubits.
In regards to claim 13 (Reagor) shows the detector of claim 1:
wherein the flux bias generator comprises: a current source configured to generate a current; Reagor [Column 17 Lines 55 - 65] teaches the flux bias device receives a direct current bias signal to generate a magnetic field, which requires a current source that generates the direct current.
a transducer arranged to convert the current into a magnetic field; Reagor [Column 17 Lines 45 - 55] teaches a flux bias device implemented as a coil that produces a magnetic field in magnetic flux areas, converting applied current into magnetic fields.
wherein the transducer is arranged such that the first flux bias and the second flux bias are provided by the magnetic field; Reagor [Column 17 Lines 45 - 55] teaches the flux bias device coil produces a magnetic field that contributes to the magnetic flux in the first and second magnetic flux areas, providing both the first and second flux bias.
In regards to claim 14 (Reagor) shows the detector of claim 13:
wherein the transducer comprises: a first coil to generate the first flux bias; and a second coil to generate the second flux bias; Reagor [Column 17 Lines 45 - 55] teaches a flux bias device implemented as a coil that produces a magnetic field in the first and second magnetic flux areas, functioning as separate coils that generate distinct flux biases for different parts of the circuit.
In regards to claim 16 (Reagor) shows a method of reading out a state of a data qubit, the method comprising: providing a flux qubit comprising:
an inductor; Reagor [Column 6 Lines 15 - 25] teaches a qubit device that includes an inductor.
a SQUID loop comprising at least one Josephson junction; Reagor [Column 6 Lines 15 - 25] teaches Josephson junctions arranged in a loop structure that functions as a SQUID loop.
a capacitor, wherein the inductor, the SQUID loop and the capacitor are connected to each other in parallel; Reagor [Column 6 Lines 40 - 55] teaches a capacitor, and the inductor, Josephson junctions and capacitor connected in parallel between the same circuit nodes.
tuning a resonance frequency of the data qubit to the frequency of interaction such that the flux qubit is coupled to the data qubit and the state of the data qubit is mapped to an energy state of the flux qubit; Reagor [Column 14 Lines 45 - 55] teaches tuning the frequency of one qubit to match another qubit’s frequency to enable coupling, allowing the state of one qubit to be mapped to the other through their interaction.
and a resonance frequency of the flux qubit is tuned to a frequency of interaction; Reagor [Column 11 Lines 1 - 10] teaches modifying external magnetic fluxes to tune the qubit frequency for interaction with another qubit.
Reagor differs from the claimed invention in that it does not explicitly disclose wherein the flux qubit is arranged to exhibit a first flux state and a second flux state; applying a first value of a first flux bias through the flux qubit, such that the energies of the first and the second flux states of the flux qubit are substantially identical; applying a first value of a second flux bias through the SQUID loop, such that a barrier between the first flux state and the second flux state is minimized; applying a second value of the first flux bias, such that the energies of the first and the second flux states of the flux qubits are different; applying a second value of the second flux bias, such that the flux qubit is decoupled from the data qubit and the energy state of the flux qubit is mapped to a superposition of the first flux state or the second flux state; determining whether the flux qubit is in the first flux state or the second flux state; and outputting a signal in dependence on whether the flux qubit is in the first flux state or the second flux state.
Harris teaches wherein the flux qubit is arranged to exhibit a first flux state and a second flux state; Harris [0063] teaches an rf-SQUID flux qubit whose two states are the two directions of circulating current, corresponding to a left well and a right well of a bistable double-well potential.
Harris teaches applying a first value of a first flux bias through the flux qubit, such that the energies of the first and the second flux states of the flux qubit are substantially identical; Harris [0063] teaches the two potential minima can be degenerate, having substantially the same energy.
Harris teaches applying a first value of a second flux bias through the SQUID loop, such that a barrier between the first flux state and the second flux state is minimized; Harris [0084] teaches adiabatically reducing the height of the energy barrier to zero or near zero by tuning the flux through the split-junction (SQUID) loop.
Harris teaches applying a second value of the first flux bias, such that the energies of the first and the second flux states of the flux qubits are different; Harris [0074] teaches raising the potential minimum of one well relative to the other by tuning the magnetic flux, so the two flux states have different energies.
Harris teaches applying a second value of the second flux bias, such that the flux qubit is decoupled from the data qubit and the energy state of the flux qubit is mapped to a superposition of the first flux state or the second flux state; Harris [0087] teaches raising the energy barrier to lock the state into a well and removing the coupling, decoupling the qubit from the other qubit.
Harris differs from the claimed invention in that it does not explicitly disclose determining whether the flux qubit is in the first flux state or the second flux state; and outputting a signal in dependence on whether the flux qubit is in the first flux state or the second flux state.
Berkley teaches determining whether the flux qubit is in the first flux state or the second flux state; Berkley [0047] and [0048] teach determining the qubit state from the transmitted power through the variable transformer circuit, which differs for the 0 and 1 states.
Berkley teaches and outputting a signal in dependence on whether the flux qubit is in the first flux state or the second flux state; Berkley [0048] teaches the readout produces a first output voltage for the 0 state and a second output voltage for the 1 state.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to provide the flux qubit with a controllable bistable double-well potential, enabling reliable preparation and locking of distinct flux states, with a reasonable expectation of success as both references address superconducting flux qubits.
It would have been obvious to one of ordinary skill in the art to further combine Reagor, Harris, and Berkley to determine and output the resulting flux state of the qubit using a non-dissipative DC-SQUID readout circuit, with a reasonable expectation of success as the references address superconducting qubit readout.
In regards to claim 18 (Reagor) shows the method of claim 16:
wherein a first time interval between generating the first value of the second flux bias and generating the second value of the second flux bias is determined based on a degree of interaction such that the state of the data qubit is entirely mapped to the flux qubit; Reagor [Column 14 Lines 45 - 60] teaches precisely timing qubit interactions, where a SWAP-type operation is realized by waiting for a time period related to the coupling strength, and different classes of operations are implemented by varying the waiting time.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over US11070210B2 (Reagor) in view of US20100148853A1 (Harris), US20130278283A1 (Berkley), and further in view of US20150358022A1 (McDermott).
In regards to claim 8 (Reagor modified by Harris and Berkley) does not show the detector of claim 1: wherein the measurement unit comprises: a single flux quantum SFQ circuit arranged to measure a flux generated by the flux qubit; and a discriminator; wherein the discriminator is configured to determine whether the flux qubit is in the first flux state or in the second flux state based on the output of the single flux quantum SFQ circuit.
McDermott teaches wherein the measurement unit comprises: a single flux quantum SFQ circuit arranged to measure a flux generated by the flux qubit; McDermott [0042] and [0104] teach single flux quantum (SFQ) circuitry integrated with a superconducting qubit and used to measure the qubit state.
Berkley teaches and a discriminator; wherein the discriminator is configured to determine whether the flux qubit is in the first flux state or in the second flux state based on the output of the single flux quantum SFQ circuit; Berkley [0048] teaches distinguishing between the 0 and 1 states of the qubit based on the output signal, functioning as a discriminator.
It would have been obvious to one of ordinary skill in the art to further combine Reagor, Harris, Berkley, and McDermott to read out the resulting flux state with single flux quantum circuitry integrated at the millikelvin stage, reducing measurement hardware, with a reasonable expectation of success as the references address superconducting qubit readout.
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over US11070210B2 (Reagor) in view of US20100148853A1 (Harris), US20130278283A1 (Berkley), and further in view of US20090082209A1 (Bunyk).
In regards to claim 15 (Reagor modified by Harris and Berkley) does not show the detector of claim 14: wherein the inductor comprises a first gradiometric coil and the first coil comprises a second gradiometric coil, and wherein the first gradiometric coil and the second gradiometric coil are configured such that the first flux bias is mainly coupled to the inductor and a coupling of the second flux bias from the second coil to the inductor is reduced.
Bunyk teaches wherein the inductor comprises a first gradiometric coil and the first coil comprises a second gradiometric coil; Bunyk [0107] teaches ladders inductively coupled to a gradiometric transformer, providing gradiometric coils in the superconducting circuit.
Bunyk teaches and wherein the first gradiometric coil and the second gradiometric coil are configured such that the first flux bias is mainly coupled to the inductor and a coupling of the second flux bias from the second coil to the inductor is reduced; Bunyk [0107] teaches the gradiometric transformer design causes the control-current signals to subtract and cancel, selectively coupling the desired flux while reducing unwanted coupling and improving resistance to external magnetic noise.
It would have been obvious to one of ordinary skill in the art to further combine Reagor, Harris, Berkley, and Bunyk to employ gradiometric coils so the first flux bias couples mainly to the inductor while unwanted coupling of the second flux bias is cancelled, improving resistance to magnetic noise, with a reasonable expectation of success as the references address superconducting flux-control circuits.
Claims 19 – 24 and 26 – 28 are rejected under 35 U.S.C. 103 as being unpatentable over US11070210B2 (Reagor) in view of US20100148853A1 (Harris) and further in view of US20130278283A1 (Berkley).
In regards to claim 19 (Reagor) shows a method comprising:
providing a data qubit and a measurement qubit for measuring a state of the data qubit; Reagor [Column 14 Lines 30 - 40] teaches a quantum integrated circuit including multiple qubit devices where one qubit can be coupled to another to perform operations.
exciting the data qubit into an excited state; Reagor [Column 14 Lines 60 - 65] teaches using a microwave source to drive transitions between computational basis states, exciting the data qubit.
Reagor differs from the claimed invention in that it does not explicitly disclose biasing the measurement qubit into a single well potential energy configuration; tuning the measurement qubit so that a photon from the excited state of the data qubit is transferred to the measurement qubit; biasing the measurement qubit containing the transferred photon into a double well potential energy configuration; and raising a potential barrier between a first well and a second well of the double well potential energy configuration, wherein either the first well or the second well comprises the transferred photon, and wherein the raised potential well prevents leakage of the transferred photon into an adjacent well of the double well potential energy configuration.
Harris teaches biasing the measurement qubit into a single well potential energy configuration; Harris [0084] teaches adiabatically reducing the barrier of the qubit to zero or near zero, bringing the qubit into a single-well quantum regime.
Harris teaches tuning the measurement qubit so that a photon from the excited state of the data qubit is transferred to the measurement qubit; Harris [0084] and [0085] teach lowering the barrier and turning on a ferromagnetic coupling so the state is transferred from the first qubit to the second qubit by tunneling into the energetically favorable well.
Harris teaches biasing the measurement qubit containing the transferred photon into a double well potential energy configuration; Harris [0086] and [0087] teach that after the state is transferred, the qubit is characterized by a bistable double-well potential.
Harris teaches and raising a potential barrier between a first well and a second well of the double well potential energy configuration, wherein either the first well or the second well comprises the transferred photon, and wherein the raised potential well prevents leakage of the transferred photon into an adjacent well of the double well potential energy configuration; Harris [0087] teaches adiabatically raising the energy barrier to prevent the qubit from tunneling out of the well it occupies, transitioning it back into the classical regime.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to transfer the data qubit state to the measurement qubit and lock it into a stable double-well flux state for reliable, low-crosstalk readout, with a reasonable expectation of success as both references address superconducting flux qubits.
In regards to claim 20 (Reagor) shows the method of claim 19:
wherein tuning the measurement qubit so that the photon from the excited state of the data qubit is transferred to the measurement qubit comprises tuning the measurement qubit to be in resonance with the data qubit in the excited state; Reagor [Column 14 Lines 45 - 55] teaches tuning the qubit frequency of one qubit toward the qubit frequency of the second qubit to bring them into resonance for state transfer.
In regards to claim 21 (Reagor) does not show the method of claim 19: wherein biasing the measurement qubit containing the transferred photon into the double well potential energy configuration comprises tilting a potential energy curve of the measurement qubit so that energy states of the measurement qubit containing the transferred photon are mapped to the first well and the second well of the double well potential energy configuration.
Harris teaches wherein biasing the measurement qubit containing the transferred photon into the double well potential energy configuration comprises tilting a potential energy curve of the measurement qubit so that energy states of the measurement qubit containing the transferred photon are mapped to the first well and the second well of the double well potential energy configuration; Harris [0074] teaches raising the potential minimum of one well relative to the other, tilting the bistable potential so the state is localized into the shallow or deep well.
It would have been obvious to one of ordinary skill in the art to combine Reagor and Harris to transfer the data qubit state to the measurement qubit and lock it into a stable double-well flux state for reliable, low-crosstalk readout, with a reasonable expectation of success as both references address superconducting flux qubits.
In regards to claim 22 (Reagor) shows the method of claim 19:
further comprising reading out energy states of the measurement qubit; Reagor [Column 14 Lines 1 - 10] teaches using a microwave source to send signals to a readout resonator that detects the quantum state of the qubit device, allowing determination of the qubit’s energy state.
In regards to claim 23 (Reagor) shows the method of claim 22:
wherein reading out the energy states of the measurement qubit comprises applying microwave reflectometry to the measurement qubit; Reagor [Column 14 Lines 10 - 20] teaches producing a readout response signal by reflecting the readout interrogation signal, where the resonance frequency of the readout resonator is influenced by the quantum state of the qubit device, demonstrating microwave reflectometry.
In regards to claim 24 (Reagor modified by Harris) does not show the method of claim 22: wherein reading out the energy states of the measurement qubit comprises reading out a flux difference between a first energy state and a second energy state of the measurement qubit.
Berkley teaches wherein reading out the energy states of the measurement qubit comprises reading out a flux difference between a first energy state and a second energy state of the measurement qubit; Berkley [0044] and [0047] teach coupling the magnetic flux representative of the qubit state to a DC-SQUID and determining the state from the resulting transmitted power, thereby reading out the flux difference between the two states.
It would have been obvious to one of ordinary skill in the art to further combine Reagor, Harris, and Berkley to read out the flux difference between the two states using a DC-SQUID readout circuit, with a reasonable expectation of success as the references address superconducting qubit readout.
In regards to claim 26 (Reagor) shows the method of claim 19:
wherein the data qubit is a transmon qubit; Reagor [Column 14 Lines 20 - 30] teaches the quantum integrated circuit can include transmon qubit devices, described as charge qubit devices with a single Josephson junction and a shunt capacitance.
In regards to claim 27 (Reagor) shows the method of claim 19:
wherein the measurement qubit is a flux qubit; Reagor [Column 14 Lines 25 - 35] teaches flux qubit devices including flatsonium and fluxonium qubit devices, demonstrating the measurement qubit can be implemented as a flux qubit.
In regards to claim 28 (Reagor) shows the method of claim 19:
wherein the data qubit is on a first substrate and the measurement qubit is on a second substrate that is bonded to the first substrate; Reagor [Column 2 Lines 45 - 55] teaches quantum circuit systems formed as a three-dimensional device array created by stacking two-dimensional wafers with connections between wafers, demonstrating qubits positioned on different bonded substrates.
Claim 25 is rejected under 35 U.S.C. 103 as being unpatentable over US11070210B2 (Reagor) in view of US20100148853A1 (Harris), US20130278283A1 (Berkley), and further in view of US20150358022A1 (McDermott).
In regards to claim 25 (Reagor modified by Harris and Berkley) does not show the method of claim 24: wherein reading out the flux difference is performed using a single flux quantum (SFQ) to measure the flux difference.
McDermott teaches wherein reading out the flux difference is performed using a single flux quantum (SFQ) to measure the flux difference; McDermott [0042] and [0104] teach single flux quantum (SFQ) circuitry integrated with the superconducting qubit to perform measurement of the qubit state.
It would have been obvious to one of ordinary skill in the art to further combine Reagor, Harris, Berkley, and McDermott to measure the flux difference using single flux quantum circuitry for fast, compact readout, with a reasonable expectation of success as the references address superconducting qubit readout.
Response to Arguments
Applicant's arguments filed on June 16, 2026 have been fully considered but are not persuasive for the reasons set forth below.
Applicant argues that the amended claim 1 further defines the capacitor structure of the flux qubit and that the Office has not shown this structure in the cited art. The argument is not persuasive. Reagor discloses a physical capacitor implemented as capacitor pads formed of superconducting material on the substrate, as set forth at Reagor Column 7 Lines 1 - 15, and further discloses the capacitor connected in parallel with the inductor between a first circuit node and a second circuit node on opposite sides of the SQUID loop, with the connections between devices formed by superconducting wire, as set forth at Reagor Column 6 Lines 40 - 55. Reagor therefore teaches the first and second capacitor pads on respective sides of the SQUID loop, each connected to the inductor by a wire, as recited in amended claim 1.
Applicant argues that Reagor discloses tuning for a SWAP logic gate rather than a readout, and does not disclose the claimed ordered sequence of flux-bias operations or the underlying double-well physics. The present rejection does not rely on Reagor for these features. Harris teaches a flux qubit having a bistable double-well potential in which the barrier height and the tilt of the potential are independently controlled by flux bias to prepare, transfer, and lock the qubit state, as set forth in the rejection above.
Applicant argues that the cited art fails to disclose biasing the measurement qubit into a single well and then a double well potential energy configuration and raising a potential barrier to prevent leakage. Harris expressly teaches lowering the barrier to bring the qubit into a single-well quantum regime, transferring the state through a controllable coupling, and adiabatically raising the barrier to lock the state into a well and prevent tunneling between the wells. Meyers is no longer relied upon.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ANWER AHMED ALAWDI whose telephone number is (703)756-1018. The examiner can normally be reached Monday - Friday 8:00 am - 5:30 pm.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jack Chiang can be reached on (571)-272-7483. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/ANWER AHMED ALAWDI/Examiner, Art Unit 2851 /JACK CHIANG/ Supervisory Patent Examiner, Art Unit 2851
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