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 .
Specification
The lengthy specification has not been checked to the extent necessary to determine the presence of all possible minor errors. Applicant’s cooperation is requested in correcting any errors of which applicant may become aware in the specification.
Claim Rejections - 35 USC § 112 - Indefinite
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.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 1 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.
Claim 1, 2nd to last line, recites:
forming a coplanar microwave waveguide on the substrate in proximity to the array of ...
The Examiner notes that the term “proximity” is used several times in the application, but there does not appear to be a definition or other teachings that would make it clear to one of ordinary skill in the art how close the waveguide must be to be “in proximity to” the array.
The Examiner notes that this claim is very similar to claim 1 in US Patent No. 12,014,246. Applicant is encouraged to consider the claims in that patent when responding to this Action, particularly with regard to possible Double Patenting issues.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 6,472,681 (Kane) at FIG. 1 illustrates two qubits cells 2, 3 each containing an atom 5, 6 of phosphorous-31 in a silicon substrate 4 with a barrier 9 separating the substrate 4 from metal gates 8, 10 used to control resonance frequency of the nuclear spin qubits and to control electron-mediated coupling between adjacent nuclear spin.
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See, for example, the bottom of col. 4:
(2) Referring first to FIG. 1 (not to scale), a 1-Dimensional array 1 having two cells 2 and 3 comprises a Si substrate 4 into which two donor atoms 5 and 6 of .sup.31 P are introduced 200 .ANG. beneath the surface 7. There is one atom of .sup.31 P in each cell and the atoms are separated by less than 200 .ANG.. Conducting A-gates 8 are laid down on a SiO.sub.2 insulating layer 9 above the Si substrate 4, each A-gate being directly above a respective .sup.31 P atom. Conducting J-gates 10 are laid down on the insulating layer 9 between each cell 2 and 3. A step 11 over which the gates cross localises the gates electric fields in the vicinity of the donor atoms 5 and 6.
(3) The nuclear spins of the donor atoms 5 and 6 are the quantum states or "qubits" in which binary information is stored and manipulated. The A-gates 8 control the resonance frequency of the nuclear spin qubits, while J-gates 10 control the electron-mediated coupling between adjacent nuclear spins.
FIG. 6a illustrates E-gates at the edge of the array. The E-gates are used to initialize the qubits by pulling electrons under the E-gates into the vicinity of the edge qubit donor.
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FIG. 6b illustrates a cross-sectional view of FIG. 6a showing an electron tunneling from under one E-gate, through the phosphorous atom, and to the area under the other E-gate. This operation is used to measure the qubit.
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See the middle of col. 4:
FIG. 6 illustrates a configuration at the edge of the array for polarising and detecting nuclear spins. FIG. 6(a) is a pictorial view of the arrangement When positively biased, E-gates pull electrons from ohmic contacts (not shown) into the vicinity of the edge qubit donor. FIG. 6(b) is a section showing the .sup.31 P donor weakly coupled to 2 DEG's; if the transition is allowed, an electron can tunnel through the donor state. FIG. 6(c) illustrates the "spin diode" configuration, in which electron spin states at the Fermi level on opposite sides of the donor have opposite polarity. Resonant tunnelling from one side to the other will flip the nuclear spin on the donor, so that the nuclear spin is polarised by an electrical current. FIG. 6(d) illustrates the "single electron spin valve" configuration, in which electrons cannot tunnel onto the donor unless it can transfer its spin to the nucleus, resulting in a spin blockade if the electron and nuclear spins initially point in the same direction. An electron traversing across the donor must flip the nuclear spin twice, however, so the initial nuclear spin polarisation is preserved.
The initialization and measurement is discussed in more detail beginning at the bottom of col. 7. In particular, see col. 8, 1st paragraph:
(32) To accomplish these tasks in the proposed computer, qubits at the edge of the array are weakly coupled to two dimensional electron gases (2 DEG's) that are confined to the barrier-Si interface by a positive potential on E-gates (a field effect transistor in enhancement mode); see FIG. 6a. The nuclear spin qubit is probed by an electron tunnelling through a bound state at the donor; see FIG. 6b. When B.noteq.0 the electron energy levels are discrete and electron spin levels are split by 2 .mu..sub.B B. When the Landau level filling factor v<1, the electron spins are completely polarised at low temperature. When v>1, however, electrons must occupy the higher 10 energy spin level and states at the Fermi level (E.sub.F) are polarised in the opposite direction than for v<1 (For simplicity, neglecting the valley degeneracy of the electrons in Si. Also, many body "skyrmion" effects that can reduce the electron spin polarisation are small in Si and are also neglected).
The basic operation is described in the middle of col. 8:
(10) An electric field applied at the A-gate to the electron-donor system shifts the electron wave function envelope away from the nucleus and reduces the hyperfine interaction. The size of this shallow donor Stark shift in Si, is shown in FIG. 2 for a donor 200 .ANG. beneath a gate. A donor nuclear spin-electron system close to an A-gate functions as a voltage controlled oscillator: the precession frequency of the nuclear spin can be controlled externally, and spins can be selectively brought into resonance with an externally applied alternating magnetic field, B.sub.AC =10.sup.-3 T, allowing arbitrary rotations to be performed on the nuclear spin.
(11) Quantum mechanical computation requires, in addition to single spin rotations, the two qubit "controlled rotation" operation, which rotates the spin of a target qubit through a prescribed angle if and only if the control qubit is oriented in a specified direction, and leaves the orientation of the control qubit unchanged. Performing such two spin operations requires coupling between two donor-electron spin systems, which will arise from the electron spin exchange interaction when the donors are sufficiently close to each other. The Hamiltonian of two coupled donor nuclei-electron systems is:
US 2017/0227795 (Bishop) at FIGS. 1 and 2 illustrate a microwave to optical transducer including a qubit 104 on a substrate 102 with a superconducting microwave channel 106 connecting the qubit 104 to a microwave-to-optical transducing cavity 111, 130 and an optical waveguide 108.
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See also:
[0021] Referring now to the drawings in which like numerals represent the same or similar elements and initially to FIG. 1, a cross-sectional view of a microwave-to-optical transducer 100 is shown. A bottom substrate 102 is shown as having, e.g., a quantum computing device 104 (a “qubit”) that provides, e.g., single-photon level microwave signals along a superconducting channel 106 to a transducing cavity 130. It is specifically contemplated that the bottom substrate 102 may be formed from silicon, but any other appropriate substrate material may be used in its place. After converting the microwave signal to an optical signal in the transducing cavity 130, the optical signal couples with a waveguide 108 and is transmitted to its destination. The cavity 130 is capacitively coupled to the superconducting channel 106, which may be either a microwave transmission line, or to other resonating structures (e.g., the qubit 104 itself).
FIG. 1 illustrates a top substrate 120 including a cavity 112 and a central pin 114 in the top substrate 120, and FIG. 2 illustrates a similar cavity 111 on the bottom substrate 102. The cavities form a microwave resonator 122. See, for example:
[0022] A top substrate 120 includes a cylindrical cavity 112 and a central pin 114. In one embodiment, the cavity may have a radius of about 2.5 mm and the central pin 114 may have a radius of about 2 mm and a height of about 2 mm. It is specifically contemplated that the top substrate 120 may be formed from silicon, but any other appropriate substrate material may be used in its place. The sidewalls of the cavity 112 and the central pin 114 are coated with a superconducting film. The cavity 112 joins with a similar cavity 111 on the bottom substrate 102 to form a microwave resonator 122, which is connected to ground. The bottom cavity 111 has an exemplary depth of 0.67 mm and an exemplary radius of 1.98 nm. It should be noted that the top substrate 120 should not come into contact with the bottom substrate, at least in regions with superconducting films or the channel 106, to prevent damage to those structures. The central pin 114 approaches, without touching, an optical resonator 110 on a pedestal 115 in the bottom substrate 102. It is specifically contemplated that the optical resonator 110 is formed from silicon and silicon-germanium, with the silicon-germanium providing a strain on the silicon material. In one embodiment, the optical resonator 110 may have a radius of about 2 mm and a thickness of about 0.1 mm. This strain creates the electro-optic effect in the silicon as it deforms the crystalline structure of the silicon.
FIG. 5 illustrates another embodiment with an electro-optical modulator 506 and a semi-transparent, partially-mirrored plate 502 and a mirror 504 forming a Fabry-Perot cavity. There is also an inductor 514 and capacitor 512 forming a microwave resonator, and a qubit 510 coupled to the microwave resonator via capacitor 516.
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The EOM 506 receives an optical beam 508 through the semi-transparent plate 502. The qubit 510 is injected into the microwave resonator 512, 514 through capacitor 516 and modulates the optical signal in the EOM 506. See, for example:
[0037] Referring now to FIG. 5, an abstract diagram of electro-optic modulation of an optical carrier is shown. An optical beam 508 is shown passing through semi-transparent, partially mirrored plate 502, through an electro-optic modulator (EOM) region 506, and reflecting from a mirror 504. The mirrors 502 and 504 form a Fabry-Perot cavity. In the present embodiments, the EOM region 506 is a resonator at the optical wavelengths. An inductor 514 and the plates of capacitor 512 form a resonator at a microwave frequency, with the output of qubit 510 being injected into the resonator through capacitor 516. As the microwave signal oscillates in the resonator, charges build and switch on capacitor plates 512 around the EOM region 506. These charges create an oscillating electric field that causes a phase shift in the optical signal.
US 2020/0160204 (Johnson) at FIG. 1 illustrates a quantum computer 102 including a plurality of qubits 104, a measurement unit 110, and a control unit 106.
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Control Unit 106.
The control unit 106 provides control signals to the qubits 104. See, for example:
[0110] The quantum computer 102 includes a control unit 106, which may include any of a variety of circuitry and/or other machinery for performing the functions disclosed herein. The control unit 106 may, for example, consist entirely of classical components. The control unit 106 generates and provides as output one or more control signals 108 to the qubits 104. The control signals 108 may take any of a variety of forms, such as any kind of electromagnetic signals, such as electrical signals, magnetic signals, optical signals (e.g., laser pulses), or any combination thereof.
Examples of the control units 106 used with different qubits are provided at [0111]-[0119].
The control signals 108 from the control unit 106 cause the qubits to change state or undergo a logical gate operation. See, for example:
[0121] The control signals 108 may, for example, include one or more state preparation signals which, when received by the qubits 104, cause some or all of the qubits 104 to change their states. Such state preparation signals constitute a quantum circuit also referred to as an “ansatz circuit.” The resulting state of the qubits 104 is referred to herein as an “initial state” or an “ansatz state.” The process of outputting the state preparation signal(s) to cause the qubits 104 to be in their initial state is referred to herein as “state preparation” (FIG. 2A, section 206). A special case of state preparation is “initialization,” also referred to as a “reset operation,” in which the initial state is one in which some or all of the qubits 104 are in the “zero” state i.e. the default single-qubit state. More generally, state preparation may involve using the state preparation signals to cause some or all of the qubits 104 to be in any distribution of desired states. In some embodiments, the control unit 106 may first perform initialization on the qubits 104 and then perform preparation on the qubits 104, by first outputting a first set of state preparation signals to initialize the qubits 104, and by then outputting a second set of state preparation signals to put the qubits 104 partially or entirely into non-zero states.
[0122] Another example of control signals 108 that may be output by the control unit 106 and received by the qubits 104 are gate control signals. The control unit 106 may output such gate control signals, thereby applying one or more gates to the qubits 104. Applying a gate to one or more qubits causes the set of qubits to undergo a physical state change which embodies a corresponding logical gate operation (e.g., single-qubit rotation, two-qubit entangling gate or multi-qubit operation) specified by the received gate control signal. As this implies, in response to receiving the gate control signals, the qubits 104 undergo physical transformations which cause the qubits 104 to change state in such a way that the states of the qubits 104, when measured (see below), represent the results of performing logical gate operations specified by the gate control signals. The term “quantum gate,” as used herein, refers to the application of a gate control signal to one or more qubits to cause those qubits to undergo the physical transformations described above and thereby to implement a logical gate operation.
[0126] After the measurement unit 110 has performed one or more measurement operations on the qubits 104 after they have performed one set of gate operations, the control unit 106 may generate one or more additional control signals 108, which may differ from the previous control signals 108, thereby causing the qubits 104 to perform one or more additional quantum gate operations, which may differ from the previous set of quantum gate operations. The process described above may then be repeated, with the measurement unit 110 performing one or more measurement operations on the qubits 104 in their new states (resulting from the most recently-performed gate operations).
The measurement unit 110 provides feedback to the control unit 106, such as for error correction. See, for example:
[0120] Although not shown explicitly in FIG. 1 and not required, the measurement unit 110 may provide one or more feedback signals 114 to the control unit 106 based on the measurement signals 112. For example, quantum computers referred to as “one-way quantum computers” or “measurement-based quantum computers” utilize such feedback 114 from the measurement unit 110 to the control unit 106. Such feedback 114 is also necessary for the operation of fault-tolerant quantum computing and error correction.
[0124] The quantum computer 102 also includes a measurement unit 110, which performs one or more measurement operations on the qubits 104 to read out measurement signals 112 (also referred to herein as “measurement results”) from the qubits 104, where the measurement results 112 are signals representing the states of some or all of the qubits 104. In practice, the control unit 106 and the measurement unit 110 may be entirely distinct from each other, or contain some components in common with each other, or be implemented using a single unit (i.e., a single unit may implement both the control unit 106 and the measurement unit 110). For example, a laser unit may be used both to generate the control signals 108 and to provide stimulus (e.g., one or more laser beams) to the qubits 104 to cause the measurement signals 112 to be generated.
[0125] In general, the quantum computer 102 may perform various operations described above any number of times. For example, the control unit 106 may generate one or more control signals 108, thereby causing the qubits 104 to perform one or more quantum gate operations. The measurement unit 110 may then perform one or more measurement operations on the qubits 104 to read out a set of one or more measurement signals 112. The measurement unit 110 may repeat such measurement operations on the qubits 104 before the control unit 106 generates additional control signals 108, thereby causing the measurement unit 110 to read out additional measurement signals 112 resulting from the same gate operations that were performed before reading out the previous measurement signals 112. The measurement unit 110 may repeat this process any number of times to generate any number of measurement signals 112 corresponding to the same gate operations. The quantum computer 102 may then aggregate such multiple measurements of the same gate operations in any of a variety of ways.
There can be many variations of the number and arrangement of qubits and quantum gates. See, for example:
[0106] Referring to FIG. 1, a diagram is shown of a system 100 implemented according to one embodiment of the present invention. Referring to FIG. 2A, a flowchart is shown of a method 200 performed by the system 100 of FIG. 1 according to one embodiment of the present invention. The system 100 includes a quantum computer 102. The quantum computer 102 includes a plurality of qubits 104, which may be implemented in any of the ways disclosed herein. There may be any number of qubits 104 in the quantum computer 104. For example, the qubits 104 may include or consist of no more than 2 qubits, no more than 4 qubits, no more than 8 qubits, no more than 16 qubits, no more than 32 qubits, no more than 64 qubits, no more than 128 qubits, no more than 256 qubits, no more than 512 qubits, no more than 1024 qubits, no more than 2048 qubits, no more than 4096 qubits, or no more than 8192 qubits. These are merely examples, in practice there may be any number of qubits 104 in the quantum computer 102.
[0107] There may be any number of gates in a quantum circuit. However, in some embodiments the number of gates may be at least proportional to the number of qubits 104 in the quantum computer 102. In some embodiments the gate depth may be no greater than the number of qubits 104 in the quantum computer 102, or no greater than some linear multiple of the number of qubits 104 in the quantum computer 102 (e.g., 2, 3, 4, 5, 6, or 7).
[0108] The qubits 104 may be interconnected in any graph pattern. For example, they be connected in a linear chain, a two-dimensional grid, an all-to-all connection, any combination thereof, or any subgraph of any of the preceding.
It also teaches that portions of the “quantum computer” can be implemented as a classical computer. See, for example:
[0109] As will become clear from the description below, although element 102 is referred to herein as a “quantum computer,” this does not imply that all components of the quantum computer 102 leverage quantum phenomena. One or more components of the quantum computer 102 may, for example, be classical (i.e., non-quantum components) components which do not leverage quantum phenomena.
US 10,578,891 (Schmeing) at FIG. 3 illustrates a quantum processor including a qubit 30 and drive line 60, a controller producing the microwave signals to drive line 60, optical communication medium 70, 72.
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The qubits 30 are formed from a pair of capacitors 41, 42 and transducer 10 is connected to drive line 60 and used to communicate with the quantum device via microwave signals. See, for example, the paragraph spanning cols. 9-10 and col. 10, 1st two full paragraphs:
(44) As illustrated in FIG. 3, the circuit may for example be embodied as a superconducting microwave circuit 1 configured as a quantum information processing device. That is, the circuit 1 may further comprise one or more superconducting qubits 30 and corresponding drive lines 60, connected to the qubits 30 (predefined) for driving the qubits 30, in operation. Only one qubit 30 and one drive line 60 are depicted in FIG. 3, for conciseness, but it should be appreciated that more qubits 30 and drive lines 60 can be utilized. Each qubit 30 includes a pair 40 of capacitor plates 41, 42, which are coupled via a Josephson junction 50. The qubits 30 may notably serve as computational qubits or as couplers in the quantum information processing device. The couplers may have a fixed or tunable frequency in practice. For example, the frequency of the coupler may be modulated so as to drive energy transitions in the quantum information processing device. In other words, energy transitions in the system can be driven by applying harmonic microwave signals (i.e., coherent microwave tones) to the tunable coupler. A controller (e.g., including one or more drive lines 60) can be used to apply harmonic microwave signals or microwave signal pulses to components of the circuit and trigger the desired transitions. This may notably require adjusting amplitudes and phases of the signals applied, in addition to modulating their frequency.
(45) One or more transducers are relied on to communicate with the quantum device over long distances. For example, and as depicted in FIG. 3, a transducer 10 can be connected to a drive line 60 so as to drive the qubit 30. In other words, a microwave signal can be applied to the drive line 60 via the transducer 10, whose electrodes 21, 22 (FIG. 1) are suitably connected to electrically conducting structures of the drive line 60, upon optical stimulation of the transducer 10. This allows optical-to-microwave transduction via the intermediate mechanical resonator 15, to drive quantum signals, thus enabling long distance communication with the qubit 30. Conversely, a microwave signal from the quantum circuit (e.g., from the qubit 30) can be coupled back into the transducer to produce an optical signal. That is, microwave-to-optical transduction is possible, because a microwave response (a tone or a pulse) from the qubit 30 results in an electric field in the beam 15, leading to mechanical motion of the beam 15 and, in turn, modulation of light in the optical cavity (of the beam 15), which can be out-coupled (or transmitted/emitted) from the beam 15 and conveyed via an optical medium 70.
(46) To that aim, an optical communication medium 70 may be optically coupled to the circuit 1 to couple light into and/or out of the transducer 10. In variants, the circuit 1 may further include such an optical communication medium 70. While the core circuit (e.g., components 21, 22, 30 and 60) has to be superconducting (such that the chip bearing the structures 21, 22, 30 and 60 needs to be subject to certain conditions of temperatures and magnetic fields), the optical circuit 70 does not. Thus, long distance communication with the qubit 30 is possible even though the optical circuit 70 is at room temperature.
The optical waveguide is coupled to the transducer 10 using a nanobeam cavity 15. See, for example, col 10, 3rd full cavity:
(47) In FIG. 3, the nanobeam cavity 15 is assumed to be side-coupled to a waveguide 72. It may for example be side-coupled to a waveguide connected with two grating couplers. The waveguide 72 is typically integrated in the device 10. Yet, other optical coupling schemes can be contemplated, which use tapered fibers, for example.
US 11,416,762 (Naveh) teaches to score qubits. See, for example, col. 9, 2nd full paragraph:
(30) In some exemplary embodiments, the predictor may be used to provide a quality metric that is monotonically correlated to error rates of at least some LQs of the quantum circuit, such as logical output qubits of the circuit, when implementing each alternative physical representation. In some exemplary embodiments, the quality metric may be used to compute quality scores that are correlated, or oppositely correlated, to the error rates of the program, derivations thereof, or the like. For example, an increase in the quality score may indicate an increased error rate of at least some LQs. According to this example, a quality score of zero, may indicate that the circuit is error free. As another example, an increase in the quality score may indicate a decreased error rate of at least some LQs. In some cases, the predictor may utilize a quality function that decreases or increases the quality score monotonically, according to an error level of an inspected circuit. In some exemplary embodiments, any other measure of quality that is based on the errors of the logical qubits may be used, instead of or in addition to the quality score.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DARREN WOLF whose telephone number is (571)270-3378. The examiner can normally be reached Monday through Friday, 6:00 AM to 2:00 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, KENNETH N. VANDERPUYE can be reached on 571-272-3078. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/DARREN E WOLF/Primary Examiner, Art Unit 2636
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