Reused resonator induction phase gate drive signal

Abstract

Techniques regarding coupling of quantum gates are provided. For example, one or more embodiments described herein may include a method for driving multiple resonator-induced phase gates from the same signal control line. The method may include controlling quantum gate coupling via a quantum circuit by filtering resonator-induced phase gate signals from the signal control line, which is multiplexed with multiple resonator-induced phase gate signals.

Description

Background Art

[0001] The present invention relates to multiplexed signals for driving resonator-induced phase (“RIP”) gates, and more particularly, to multiplexing multiple RIP gate signal frequencies onto control lines of a quantum circuit. Summary of the Invention

[0002] An overview is given below to provide a basic understanding of one or more embodiments of the present invention. This overview is not intended to identify key or important elements, or to delineate any scope of a particular embodiment or any scope of the claims. Its sole purpose is to present concepts in a simplified form as a prelude to the more detailed description presented later. In one or more embodiments described herein, systems, methods, and / or apparatuses related to multiplexing RIP gate signals are described.

[0003] According to one embodiment, a method is provided. The method may include controlling quantum gate coupling via a quantum circuit by filtering resonator-induced phase gate signals from a signal control line, the signal control line being multiplexed with multiple resonator-induced phase gate signals.

[0004] According to another embodiment, a method is provided. The method may include routing a signal control line to a filtering resonator via a quantum circuit. Multiple resonator-induced phase gate signals may be multiplexed onto the signal control line. The method may further include coupling an output of the filtering resonator to a resonator-induced phase gate via the quantum circuit.

[0005] According to one embodiment, a system is provided. The system may include a resonator bus coupled to a filtering resonator. The filtering resonator may output a control tone driving the resonator bus from multiple control tones multiplexed onto a quantum gate control line. Brief Description of the Drawings

[0006] Figure 1 A block diagram is shown of an exemplary non-limiting quantum circuit layout in accordance with one or more embodiments described herein, which may multiplex multiple RIP gate signal frequencies onto control lines to drive multiple RIP gates.

[0007] Figure 2 A diagram is shown of an exemplary non-limiting multiplexing scheme in accordance with one or more embodiments described herein, which may illustrate multiplexing multiple RIP gate signal frequencies onto control lines.

[0008] Figure 3 An illustration is shown of an exemplary non-limiting quantum circuit in accordance with one or more embodiments described herein, the quantum circuit including at least three qubits operably coupled to at least two RIP gates driven by a single control line.

[0009] Figure 4 A diagram of an exemplary non-limiting quantum circuit during operation is shown, wherein the quantum circuit may include at least three qubits operably coupled to at least two RIP gates driven by a single control line according to one or more embodiments described herein.

[0010] Figure 5 A diagram of an exemplary non-limiting quantum circuit comprising at least four qubits operably connected to at least four RIP gates driven by a single control line is shown according to one or more embodiments described herein.

[0011] Figure 6 A diagram of an exemplary non-limiting quantum circuit during operation is shown, wherein the quantum circuit may include at least four qubits operably coupled to at least four RIP gates driven by a single control line according to one or more embodiments described herein.

[0012] Figure 7 An exemplary non-limiting graphical representation illustrating the efficacy of multiplexing multiple RIP gate signals according to one or more embodiments described herein is shown.

[0013] Figure 8 A flow chart is shown of an exemplary non-limiting method for controlling quantum gate coupling according to one or more embodiments described herein.

[0014] Figure 9 A flow chart is shown of an exemplary non-limiting method for routing RIP gate signals in a quantum circuit according to one or more embodiments described herein.

[0015] Figure 10 A block diagram is shown of an exemplary non-limiting operating environment in which one or more embodiments described herein may be facilitated. Specific embodiments

[0016] The following detailed description is illustrative only and is not intended to limit the embodiments and / or the application or uses of the embodiments. In addition, it is not intended to be bound by any express or implied information presented in the previous background or summary or detailed description.

[0017] One or more embodiments are now described with reference to the accompanying drawings, wherein the same reference numerals are used throughout to represent the same elements. In the following description, for the purpose of explanation, many specific details are set forth in order to provide a more thorough understanding of one or more embodiments. However, in various cases, it is apparent that the one or more embodiments described can be practiced without these specific details.

[0018] The RIP gate is a way to create quantum logic gates between qubits in a quantum circuit. Traditionally, controlling a RIP gate requires at least one drive line per pair of qubits. As a result, using RIP gates to control quantum coupling may be limited by the number of drive lines required. For example, as the number of qubits included in a quantum circuit increases, the number of drive lines required may also increase. Thus, the increase in drive lines may force an increase in the size of the quantum circuit, at least because positioning the drive lines close to each other may have an undesirable effect on the quantum circuit.

[0019] Various embodiments described herein may include methods, systems, and / or apparatuses for using multiple RIP gates driven by the same control line to control quantum gate coupling. One or more embodiments described herein may contemplate a quantum circuit that couples various qubits via one or more RIP gates. Additionally, one or more RIP gates may be driven by RIP gate signals multiplexed onto a common control line. In various embodiments, each RIP gate may be coupled to the control line via a filtering resonator and a capacitor. The filtering resonator may filter the drive signal of the RIP gate from the multiplexed control signal of the control line. Additionally, the bandwidth of the filtering resonator may be tuned by adjusting the coupling capacitance established by the capacitor. Thus, the drive line layout may be compressed, and crosstalk between RIP gates may be reduced to an acceptable level compatible with a gate of 99.99% fidelity. Additionally, the filtering resonator may earn the relaxation time of the Purcell effect. Additionally, the number of thermal photons of the RIP gate may be reduced by the on-chip filtering resonator.

[0020] The RIP gate is a form of quantum logic gate that can couple superconducting qubits. The RIP gate can be a full microwave multi-qubit entanglement gate that enables a high degree of flexibility in qubit frequencies. The RIP gate can operate by coupling two or more fixed-frequency qubits to a resonator bus. By adiabatically applying and removing an off-resonant pulse to the resonator bus, the system can undergo a closed loop in phase space, after which the resonator bus can remain unchanged while the qubits acquire state-dependent phases. In various embodiments, the RIP gate can be used to control qubit coupling in circuit quantum electrodynamics (“circuit QED”).

[0021] As described herein, the term “superconducting” may characterize materials that exhibit superconducting properties at or below the superconducting critical temperature, such as aluminum (e.g., superconducting critical temperature of 1.2 Kelvin) or niobium (e.g., superconducting critical temperature of 9.3 Kelvin). Additionally, those of ordinary skill in the art will recognize that other superconducting materials (e.g., hydride superconductors, such as lithium / magnesium hydride alloy) may be used in the various embodiments described herein.

[0022] Figure 1A diagram showing an exemplary non - restrictive quantum circuit layout 100 according to one or more embodiments described herein, which may illustrate the coupling of multiple RIP gates 102 to a common signal control line 104. For the sake of brevity, the repeated description of similar elements employed in other embodiments described herein is omitted. As Figure 1 shown, multiple N RIP gates 102 may be coupled to the same signal control line 104, where N is a positive integer. For example, the multiple RIP gates 102 coupled to the signal control line 104 may include, but are not limited to: a first RIP gate 102a, a second RIP gate 102b, and one or more additional RIP gates 102 up to the Nth RIP gate 102N (e.g., N is an integer greater than 2). In various embodiments, the number of RIP gates 102 coupled to the same signal control line 104 may be, for example, greater than or equal to 1 and less than or equal to 100. In various embodiments, each RIP gate 102 may be coupled to two or more superconducting qubits (e.g., as further described herein).

[0023] The RIP gate circuit 102 is coupled to the common signal control line 104 via multiple filter resonators 106 and capacitors 108. As Figure 1 shown, each RIP gate 102 may be coupled to a corresponding filter resonator 106 via a drive line 110. In various embodiments, the drive line 110 may be a superconducting resonant line. For example, the first RIP gate 102a can be coupled to the first filter resonator 106a, and the second RIP gate 102b can be coupled to the second filter resonator 106b. In the case where the quantum circuit layout 100 includes "N" RIP gates 102, the "Nth" RIP gate 102N can be coupled to the "Nth" filter resonator 106N. In various embodiments, the filter resonator 106 can be a band - pass filter resonator and / or a band - stop filter resonator. Example types of filters that can be used as the filter resonator 106 may include, but are not limited to: coplanar waveguides, cavity band - pass or cavity band - stop filters, lumped elements, combinations thereof, etc. In one or more embodiments, one or more filter resonators 106 can be a band - pass filter (e.g., a passive or active band - pass filter) derived from a cascaded high - pass and low - pass filter (e.g., a passive or active high - pass and low - pass filter). In one or more embodiments, one or more filter resonators 106 can be a band - stop filter (e.g., a passive or active band - stop filter) derived from a cascaded high - pass and low - pass filter (e.g., a passive or active high - pass and low - pass filter) coupled to a summing circuit.

[0024] The filter resonator 106 can also be coupled to the signal control line 104 via a capacitor 108. As Figure 1As shown, each filtering resonator 106 can be coupled to a corresponding capacitor 108. For example, the first filtering resonator 106a can be coupled to the first capacitor 108a, and the second filtering resonator 106b can be coupled to the second capacitor 108b. In the case where the quantum circuit layout 100 includes "N" RIP gates 102, the "N"th filtering resonator 106N can be coupled to the "N"th capacitor 108N. In various embodiments, the capacitor 108 can control the coupling capacitance between the signal control line 104 and the filtering resonator 106. Additionally, the coupling capacitance established by the capacitor 108 can affect the bandwidth of the filtering resonator 106. For example, the bandwidth of the first filtering resonator 106a can be tuned by setting the capacitance of the first capacitor 108a. Similarly, the bandwidth of the second filtering resonator 106b can be tuned by setting the capacitance of the second capacitor 108b. In the case where the quantum circuit layout 100 includes "N" RIP gates 102, the bandwidths of the "N" filtering resonators 106N can be tuned by setting the capacitances of the "N" capacitors 108N.

[0025] As Figure 1 shown, the signal control line 104 can be further coupled to one or more quantum controllers 112. The one or more quantum controllers 112 can control the excitation of various qubits coupled to the RIP gates 102. For example, the quantum controller 112 can control one or more signals carried by the signal control line 104. In different embodiments, the one or more quantum controllers 112 can include one or more multiplexers 114 that can frequency-division multiplex multiple RIP gate signals onto the signal control line 104 to control multiple RIP gates 102 coupled to the signal control line 104.

[0026] As further described herein, multiple RIP gate signals can be frequency-multiplexed onto the signal control line 104 by the quantum controller 112 (e.g., the multiplexer 114). Each RIP gate 102 can be driven by a corresponding RIP gate signal among the multiple multiplexed signals. Additionally, the filtering resonator 106 can separately filter out the RIP gate signals from the multiplexed signals based on frequency. For example, the coupling capacitance established by the capacitor 108 can set the filtering frequency adopted by the filtering resonator 106. Additionally, the output of the filtering resonator 106 can drive the RIP gate 102. In various embodiments, the corresponding filtering resonator 106 can be tuned through the corresponding coupling capacitance to filter the multiplexed signals at corresponding frequency bands. Thus, although the RIP gate signals originate from the same signal control line 104, each RIP gate 102 can also be driven by a different RIP gate signal.

[0027] Figure 2FIG. shows an exemplary non - limiting frequency reuse scheme 200 according to one or more embodiments described herein, which can characterize the multiplexing control signal 202 carried on the signal control line 104. For simplicity, the repeated description of similar elements employed in other embodiments described herein is omitted. In various embodiments, the frequency reuse scheme 200 can be used by the quantum controller 112 via a multiplexer. In one or more implementations, the quantum controller 112 can employ orthogonal frequency - division multiplexing to multiplex multiple RIP signals onto the signal control line 104.

[0028] As Figure 2 shown, the bandwidth of the multiplexing control signal can be divided into a series of non - overlapping sub - bands, and each sub - band can be used to carry a separate RIP gate signal. For example, the first RIP gate signal 204a can be carried on a frequency sub - band centered at 6.2 gigahertz (GHz). The second RIP gating signal 204b can be carried on a second sub - band, e.g., a sub - band centered at 6.3 GHz. Similarly, additional RIP gate signals can be carried on additional frequency bands, e.g., the "N" RIP gate signals 204N can be carried on a frequency sub - band centered at 6.5 GHz. The multiplexing control signal 202 can be transmitted on the signal control line 104 to each filtering resonator 106. Then, the filtering resonator 106 can filter the RIP gate signal from the multiplexed control signal based on the frequency - band division according to the tuning established by the coupling capacitance of the resonant filter 106.

[0029] Although Figure 2 frequency sub - bands centered at 6.2 GHz, 6.3 GHz, and 6.5 GHz are depicted, the architecture of frequency multiplexing is not limited thereto. Those of ordinary skill in the art will recognize that multiplexing control signals 202 with additional or alternative frequency - based divisions can also be envisioned. For example, the RIP gate signal line signal can be carried on a frequency sub - band centered at 6.1 or 6.4 GHz.

[0030] Figure 3 FIG. shows an exemplary non - limiting quantum circuit 300 (e.g., circuit QED) according to one or more embodiments described herein, which can include at least three qubits 302 coupled by at least two resonator buses 304 serving as RIP gates 102. For simplicity, the repeated description of similar elements employed in other embodiments described herein is omitted. As Figure 3 shown, the exemplary quantum circuit 300 can employ various features of the quantum circuit layout 100 described herein.

[0031] Figure 3The exemplary quantum circuit 300 depicted may include at least three qubits 302 (e.g., a first qubit 302a, a second qubit 302b, and / or a third qubit 302c). Those of ordinary skill in the art will recognize that a variety of qubit technologies may underlie one or more qubits 302. For example, the qubits 302 may be superconducting qubits (e.g., superconducting quantum interference devices “SQUIDs”), which may be lithographically defined electronic circuits that can be cooled to millikelvin temperatures to exhibit quantized energy levels (e.g., due to the quantized states of electron charge or magnetic flux). Superconducting qubits may be Josephson-junction based, such as Transmon qubits and / or the like. Additionally, superconducting qubits may be compatible with microwave control electronics and may be used with gate-based techniques or integrated cryogenic control. In various embodiments, the qubits 302 may be fixed-frequency superconducting qubits.

[0032] Furthermore, the coupling between the qubits 302 may be controlled via at least two resonator buses 304, which may serve as RIP gates 102. For example, a first resonator bus 304a may couple the first qubit 302a to the second qubit 302b. Additionally, a second resonator bus 304a may couple the second qubit 302b to the third qubit 302c. According to various embodiments described herein, the resonator buses 304 may be driven by the output of filtering resonators 106. For example, the first resonator bus 302a may be driven by the output of a first filtering resonator 106a. Additionally, the second resonator bus 302b may be driven by the output of a second filtering resonator 106b. Additionally, the coupling capacitance and thus the bandwidth of the filtering resonators 106 may be defined by capacitors 108. For example, a first capacitor 108a may set the coupling capacitance of the first filtering resonator 106a. Additionally, a second capacitor 108b may set the coupling capacitance of the second filtering resonator 106b. In one or more embodiments, the filtering resonators 106 may be bandpass filters, such as coplanar waveguides. Additionally, in various embodiments, the signal control lines 104 and / or drive lines 110 may be superconducting resonator lines. Example materials that may be included within one or more of the signal control lines 104 and / or drive lines 110 may include, but are not limited to: niobium, aluminum, lead, indium, combinations thereof, and / or the like.

[0033] Figure 4 A diagram showing an exemplary non-limiting quantum circuit 300 in operation according to one or more embodiments described herein is presented, where a frequency multiplexing control signal 202 may be carried by the signal control line 104 to control the resonator bus 304. For the sake of brevity, the repeated description of similar elements employed in other embodiments described herein is omitted. Figure 4Illustrates how the quantum circuit 300 can route the RIP gate signal from a single signal control line 104 to multiple resonator buses 304.

[0034] As Figure 4 shown, the frequency multiplexing control signal 202 can be represented by a thick black line and can be carried by the signal control line 104. For example, the frequency multiplexing control signal 202 can be multiplexed with the first RIP gate signal 204a and / or the second RIP gate signal 204b. In Figure 4 this case, the first RIP gate signal 204a can be represented by a thick dashed line carried on the drive line 110 coupled to the first filtering resonator 106a. In addition, the second RIP gate signal 204b can be represented by multiple hollow circles carried on the drive line 110 coupled to the second filtering resonator 106b.

[0035] The signal control line 104 can transmit the multiplexing control signal 202 (e.g., represented by a thick black line) to the first filtering resonator 106a, which can then filter the multiplexing control signal 202 based on frequency to output the first RIP gate signal 204a (e.g., represented by a thick dashed line). The first filtering resonator 106a can output the first RIP gate signal 204a as a control tone and transmit it to the first resonator bus 304a via the drive line 110. The first filtering resonator 106a can also block the transmission of other RIP gate signals such as the second RIP gate signal 204b to the first resonator bus 304a. Thus, the first resonator bus 304a can be driven only by the first RIP gate signal 204a output by the first filtering resonator 106a, and crosstalk from other RIP gate signals can be reduced by the first filtering resonator 106a. According to various embodiments described herein, the first filtering resonator 106a can be tuned to the frequency band of the first RIP gate signal 204a by adjusting the coupling capacitance established by the first capacitor 108a.

[0036] In addition, the signal control line 104 can transmit the multiplexed control signal 202 (e.g., represented by the thick black line) to the second filtering resonator 106b, which can thereby filter the multiplexed control signal 202 based on frequency to output a second RIP gate signal 204b (e.g., represented by the hollow circle). The second filtering resonator 106b can output the second RIP gate signal 204b as a control tone, which can be transmitted to the second resonator bus 304b via another drive line 110. In addition, the second filtering resonator 106b can block the transmission of other RIP gate signals, such as the first RIP gate signal 204a, to the second resonator bus 304b. Thus, the second resonator bus 304b can be driven only by the second RIP gate signal 204b output by the second filter oscillator 106b, and crosstalk from other RIP gate signals can be reduced by the second filtering resonator 106b. According to various embodiments described herein, by adjusting the coupling capacitance established by the second capacitor 108b, the second filtering resonator 106b can be tuned to the frequency band of the second RIP gate signal 204b.

[0037] By setting the capacitance of the first capacitor 108a to a capacitance different from that of the second capacitor 108b, the first filtering resonator 106a can filter the multiplexed control signal 202 at a frequency band different from that of the second filtering resonator 106b. Thus, the first filtering resonator 106a can output a target RIP gate signal (e.g., the first RIP gate signal 204a) while prohibiting the propagation of other RIP gate signals (e.g., the second RIP gate signal 204b) to the first resonator bus 304a. Similarly, the second filtering resonator 106b can output another target RIP gate signal (e.g., the second RIP gate signal 204b) while allowing the propagation of other RIP gate signals (e.g., the first RIP gate signal 204a) to the second resonator bus 304b.

[0038] Figure 5 A diagram showing another exemplary non-limiting quantum circuit 500 (e.g., circuit QED) according to one or more embodiments described herein is shown. The quantum circuit can include at least four qubits 302 coupled by at least four resonator buses 304 serving as RIP gates 102. For the sake of brevity, the repeated description of similar elements employed in other embodiments described herein is omitted. As Figure 5As shown, the exemplary quantum circuit 300 may incorporate various features of the quantum circuit layout 100 described herein. The quantum circuit 500 illustrates that the architectures of the various embodiments described herein are not limited to two resonator buses 304 (e.g., the architecture is not limited to controlling two RIP gates 102). For example, the quantum circuit 500 may employ a single signal control line 104 to control more than two resonator buses 304, such as four resonator buses 304. Additionally, one of ordinary skill in the art will recognize that quantum circuits that employ a single signal control line 104 to control more than four resonator buses 304 are also contemplated.

[0039] Compared to the quantum circuit 300, the exemplary quantum circuit 500 may include an additional fourth qubit 302d. Additionally, the quantum circuit 500 may also include a third resonator bus 304c and a fourth resonator bus 304d to facilitate coupling of the additional qubit 302. The quantum circuit 500 illustrates that the features of the quantum circuit layout 100 may be scaled based on the number of qubit couplings controlled by the quantum circuit. For example, when the quantum circuit employs more qubits 302, the circuit may control more RIP gates 102, and more RIP gate signals may be multiplexed onto the signal control line 104.

[0040] For example, the third resonator bus 304c may couple the third qubit 302c to the fourth qubit 302d. Additionally, the fourth resonator bus 304d may couple the fourth qubit 302d to the first qubit 302a. According to the various embodiments described herein, the resonator bus 304 may be driven by the output of a filtering resonator 106. For example, the third resonator bus 304c may be driven by the output of a third filtering resonator 106c. Additionally, the fourth resonator bus 304d may be driven by the output of a fourth filtering resonator 106d. Additionally, the coupling capacitance of the filtering resonator 106 and thus the bandwidth may be defined by a capacitor 108. For example, a third capacitor 108c may set the coupling capacitance of the third filtering resonator 106c. Additionally, a fourth capacitor 108d may set the coupling capacitance of the fourth filtering resonator 106d. In one or more embodiments, the filtering resonator 106 may be a bandpass filter, such as a coplanar waveguide. Additionally, in various embodiments, the signal control line 104 and / or the drive line 110 may be a superconducting resonator line.

[0041] Figure 6 A diagram showing an exemplary non-limiting quantum circuit 500 in operation according to one or more embodiments described herein is presented, where a frequency multiplexed control signal 202 may be carried by the signal control line 104 to control the resonator bus 304. For the sake of brevity, the repeated description of similar elements employed in other embodiments described herein is omitted. Figure 6Illustrates how quantum circuit 500 can route the RIP gate signal from a single signal control line 104 to multiple resonator buses 304.

[0042] As Figure 6 shown, the frequency multiplexing control signal 202 can be represented by a thick black line and can be carried by the signal control line 104. For example, the frequency multiplexing control signal 202 can be multiplexed with the first RIP gate signal 204a, the second RIP gate signal 204b, the third RIP gate signal 204c, and / or the fourth RIP gate signal 204d. In Figure 6 it, the first RIP gate signal 204a can be carried on the drive line 110 coupled to the first filtering resonator 106a and is represented by a thick dashed line. The second RIP gate signal 204b can be carried on the drive line 110 coupled to the second filtering resonator 106b and is represented by multiple hollow circles. The third RIP gate signal 204c can be carried on the drive line 110 coupled to the third filtering resonator 106c and is represented by multiple hollow triangles. The fourth RIP gate signal 204d can be carried on the drive line 110 coupled to the fourth filtering resonator 106d and is represented by multiple hollow diamonds. According to various embodiments described herein, each RIP gate signal can be multiplexed into non-overlapping frequency bands. For example, the first RIP gate signal 204a (e.g., represented by the Figure 6 dashed line in it) can be on a frequency sub-band centered at 6.2 GHz, the second RIP gate signal 204b (e.g., represented by the Figure 6 hollow circles in it) can be on a frequency sub-band centered at 6.3 GHz, the third RIP gate signal 204c (e.g., represented by the Figure 6 hollow triangles in it) can be on a frequency sub-band centered at 6.4 GHz, and / or the fourth RIP gate signal 204d (e.g., represented by the Figure 6 hollow diamonds in it) can be on a frequency sub-band centered at 6.5 GHz.

[0043] The signal control line 104 can transmit the multiplexed control signal 202 (e.g., represented by the thick black line) to the first filter resonator 106a, which can thereby filter the multiplexed control signal 202 based on frequency to output the first RIP gate signal 204a (e.g., represented by the thick dashed line). The first filter resonator 106a can output the first RIP gate signal 204a as a control tone, which is transmitted to the first resonator bus 304a via the drive line 110. The first filter resonator 106a can also prevent other RIP gate signals (e.g., the second RIP gate signal 204b, the third RIP gate signal 204c, and the fourth RIP gate signal 204d) from being transmitted to the first resonator bus 304a. Thus, the first resonator bus 304a can be driven only by the first RIP gate signal 204a output by the first filter resonator 106a, and crosstalk from other RIP gate signals can be reduced by the first filter resonator 106a. According to various embodiments described herein, by adjusting the coupling capacitance established by the first capacitor 108a, the first filter resonator 106a can be tuned to the frequency band of the first RIP gate signal 204a.

[0044] In addition, the signal control line 104 can transmit the multiplexed control signal 202 (e.g., represented by the thick black line) to the second filter resonator 106b, which can thereby filter the multiplexed control signal 202 based on frequency to output the second RIP gate signal 204b (e.g., represented by the hollow circle). The second filter resonator 106b can output the second RIP gate signal 204b as a control tone, which can be transmitted to the second resonator bus 304b via another drive line 110. In addition, the second filter resonator 106b can prevent other RIP gate signals (e.g., the first RIP gate signal 204a, the third RIP gate signal 204c, and the fourth RIP gate signal 204d) from being transmitted to the second resonator bus 304b. Thus, the second resonator bus 304b can be driven only by the second RIP gate signal 204b output by the second filter oscillator 106b, and crosstalk from other RIP gate signals can be reduced by the second filter resonator 106b. According to various embodiments described herein, by adjusting the coupling capacitance established by the second capacitor 108b, the second filter resonator 106b can be tuned to the frequency band of the second RIP gate signal 204b.

[0045] In addition, the signal control line 104 can transmit the multiplexed control signal 202 (e.g., represented by a thick black line) to the third filter resonator 106c, which can thereby filter the multiplexed control signal 202 based on frequency to output a third RIP gate signal 204c (e.g., represented by an open triangle). The third filter resonator 106c is capable of outputting the third RIP gate signal 204c as a control tone, which is transmitted via other drive lines 110 to the third resonator bus 304c. In addition, the third filter resonator 106c can block other RIP gate signals (e.g., can block the first RIP gate signal 204a, the second RIP gate signal 204b, and the fourth RIP gate signal 204d) from being transmitted to the third resonator bus 304c. Thus, the third resonator bus 304c can be driven only by the third RIP gate signal 204c output by the third filter resonator 106c, and crosstalk from other RIP gate signals can be reduced by the third filter resonator 106c. According to various embodiments described herein, by adjusting the coupling capacitance established by the third capacitor 108c, the third filter resonator 106c can be tuned to the frequency band of the third RIP gate signal 204c.

[0046] In addition, the signal control line 104 can transmit the multiplexed control signal 202 (e.g., represented by a thick black line) to the fourth filter resonator 106d, so that the multiplexed control signal 202 can be filtered based on frequency to output a fourth RIP gate signal 204d (e.g., represented by an open diamond). The fourth filter resonator 106d is capable of outputting the fourth RIP gate signal 204d as a control tone, which is transmitted via other drive lines 110 to the fourth resonator bus 304d. In addition, the fourth filter resonator 106d can block other RIP gate signals (e.g., can block the first RIP gate signal 204a, the second RIP gate signal 204b, and the third RIP gate signal 204c) from being transmitted to the fourth resonator bus 304d. Thus, the fourth resonator bus 304d can be driven only by the fourth RIP gate signal 204d output by the fourth filter resonator 106d, and crosstalk from other RIP gate signals can be reduced by the fourth filter resonator 106d. According to various embodiments described herein, by adjusting the coupling capacitance established by the fourth capacitor 108d, the third filter resonator 106c can be tuned to the frequency band of the fourth RIP gate signal 204d.

[0047] By setting each capacitor 108 to a different capacitance, each filter resonator 106 can filter the multiplexed control signal 202 in a different frequency band. Thus, each filter resonator 106 can output a different target RIP gate signal while prohibiting the propagation of other RIP gate signals to the corresponding resonator bus 304 of the filter resonator 106.

[0048] Figure 7 illustrates an exemplary non - limiting diagram of a graph 700 that can represent the operation of the exemplary quantum circuit 500 according to one or more embodiments described herein. For brevity, repeated descriptions of similar elements employed in other embodiments described herein are omitted. Figure 6 The graph 700 characterizes an embodiment of a frequency - multiplexing scheme 200 implemented on the exemplary quantum circuit 500 according to various embodiments described herein.

[0049] As Figure 7 shown, the first RIP gate signal 204a can be represented by "m1", the second RIP gate signal 204b can be represented by "m2", the third RIP gate signal 204c can be represented by "m3", and the fourth RIP gate signal 204d can be represented by "m4". The frequency - multiplexing scheme 200 shown in the graph 700 can achieve at least 20 dB of resonator bus 304 selectivity at the target drive frequencies of the corresponding RIP gate signals (e.g., target drive frequencies of 6.2 GHz, 6.3 GHz, 6.4 GHz, and / or 6.4 GHz). For example, the reference numerals "m5", "m6", "m7", and / or "m8" can depict crosstalk that may occur outside the 20 dB selectivity range.

[0050] Figure 8 illustrates a flowchart of an exemplary non - limiting method 800 according to one or more embodiments described herein, which can be implemented by one or more quantum circuits (e.g., circuit QED) for controlling quantum - gate coupling. For brevity, repeated descriptions of similar elements employed in other embodiments described herein are omitted.

[0051] At 802, the method 800 can include setting the bandwidth of a filtering resonator 106 by adjusting the coupling capacitance between the filtering resonator 106 and a signal control line 104 that can be multiplexed with a plurality of RIP gate signals via a quantum circuit (e.g., as illustrated by the exemplary quantum circuits 300 and / or 500). For example, the signal control line 104 can be frequency - division multiplexed, such as the multiplexing illustrated in the frequency - multiplexing scheme 200 and / or in the graph 700. In various embodiments, the filtering resonator 106 can be from a plurality of filtering resonators 106 included within the same quantum circuit. Additionally, the filtering resonator 106 can be a band - pass filter or a band - stop filter. In various embodiments, the filtering resonator 106 can be a coplanar - waveguide filter. In one or more embodiments, setting the bandwidth at 802 can be performed by setting the capacitance of one or more capacitors 108 that couple the filtering resonator 106 to the signal control line 104.

[0052] At 804, method 800 may include controlling quantum gate coupling via a quantum circuit (e.g., as illustrated by exemplary quantum circuits 300 and / or 500) by filtering a RIP gate signal from signal control line 104, wherein the RIP gate signal may be filtered from the signal control line by a filtering resonator based on frequency according to a bandwidth. For example, filtering resonator 106 may be coupled to one or more RIP gates 102 (e.g., one or more resonator buses 304 coupling multiple qubits 302). In various embodiments, signal control line 104 may drive multiple RIP gates 102, wherein crosstalk between RIP gates 102 may be reduced by filtering resonator 106.

[0053] Figure 9 A flowchart of an exemplary non - limiting method 900 in accordance with one or more embodiments described herein is shown, which may be implemented by one or more quantum circuits (e.g., circuit QED) to control quantum gate coupling. For brevity, repeated descriptions of similar elements employed in other embodiments described herein are omitted.

[0054] At 902, method 900 may include multiplexing a plurality of RIP gate signals onto signal control line 104 via a quantum controller 112. For example, signal control line 104 may be frequency - division multiplexed, such as the multiplexing illustrated in frequency multiplexing scheme 200 and / or FIG. 700. In one or more embodiments, the multiplexing at 902 may be implemented by one or more quantum controllers 112 (e.g., via one or more multiplexers 114), which may excite a quantum circuit including signal control line 104 (e.g., exemplary quantum circuits 300 and / or 500).

[0055] At 904, method 900 may include routing signal control line 104 to one or more filtering resonators 106 via a quantum circuit (e.g., as illustrated by exemplary quantum circuits 300 and / or 500). For example, signal control line 104 may convey a multiplexed control signal 202 to one or more filtering resonators 106. As illustrated at least in Figure 1 and Figures 3 to 6 the multiplexed control signal 204 may be conveyed to multiple filtering resonators 106 via signal control line 104.

[0056] At 906, method 900 may include coupling the output of one or more filter resonators 106 to one or more RIP gates 102 via a quantum circuit (e.g., as illustrated by exemplary quantum circuits 300 and / or 500). For example, each filter resonator 106 may be coupled to a corresponding RIP gate 102 (e.g., to a corresponding resonator bus 304 that couples two or more qubits 302). The output of one or more filter resonators 106 may drive the RIP gates 102.

[0057] At 908, method 900 may include setting the bandwidth of one or more filter resonators 106 via a quantum circuit (e.g., as illustrated by exemplary quantum circuits 300 and / or 500) by adjusting the coupling capacitance between one or more filter resonators 106 and signal control lines 104. For example, one or more filter resonators 106 may be coupled to signal control lines 104 via one or more capacitors 108. By adjusting the capacitance of capacitor 108, the bandwidth of filter resonator 106 may be tuned such that the filter resonator 106 outputs a RIP gate signal driven at a target frequency sub-band. In various embodiments, one or more filter resonators 106 may be set to different bandwidths and may thereby filter the multiplexed control signal 202 based on different target frequencies.

[0058] At 910, method 900 may include generating an output via a quantum circuit (e.g., as illustrated by exemplary quantum circuits 300 and / or 500) by filtering a RIP gate signal from among a plurality of multiplexed RIP gate signals multiplexed at 902 via one or more filter resonators 106. For example, filter resonator 106 may output respective RIP gate signals from multiplexed control signal 202 based on a target frequency defined by the bandwidth set at 908. In various embodiments, each filter resonator 106 may output a corresponding RIP gate signal to drive a corresponding RIP gate 102 at a different frequency.

[0059] To provide additional context for the various embodiments described herein, Figure 10 and the following discussion is intended to provide a general description of a suitable computing environment 1000 in which the embodiments described herein may be implemented. In different implementations, computing environment 1000 may illustrate one or more structural features of quantum controller 112 and / or one or more computer devices for communicating with and / or providing input to quantum controller 112. Although the embodiments have been described above in the general context of computer-executable instructions that may run on one or more computers, those skilled in the art will recognize that the embodiments may also be implemented in conjunction with other program modules and / or as a combination of hardware and software.

[0060] Typically, a program module includes routines, programs, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Additionally, those skilled in the art can understand that the method of the present invention can be practiced with other computer system configurations, including single-processor or multi-processor computer systems, minicomputers, mainframe computers, Internet of Things ("IoT") devices, distributed computing systems, and personal computers, handheld computing devices, microprocessor-based or programmable consumer electronics, etc., each of which can be operatively coupled to one or more associated devices.

[0061] Here, the illustrated embodiments of the examples can also be practiced in a distributed computing environment where certain tasks are performed by remote processing devices linked through a communication network. In a distributed computing environment, program modules can be located in local and remote memory storage devices. For example, in one or more embodiments, computer-executable components can be executed from a memory that can include one or more distributed memory units or be composed of one or more distributed memory units. As used herein, the terms "memory" and "memory unit" are interchangeable. Additionally, the code of computer-executable components can be executed in a distributed manner in one or more embodiments described herein. For example, multiple processors can combine or cooperate to execute code from one or more distributed memory units. As used herein, the term "memory" can include a single memory or memory unit at one location or multiple memories or memory units at one or more locations.

[0062] A computing device generally includes various media, which can include computer-readable storage media, machine-readable storage media, and / or communication media, and these two terms are used differently from each other as follows herein. Computer-readable storage media or machine-readable storage media can be any available storage media accessible by a computer and include volatile and non-volatile media, removable and non-removable media. By way of example and not limitation, computer-readable storage media or machine-readable storage media can be implemented in conjunction with any method or technology for storing information such as computer-readable or machine-readable instructions, program modules, structured data, or unstructured data.

[0063] A computer-readable storage medium may include, but is not limited to, random access memory (“RAM”), read only memory (“ROM”), electrically erasable programmable read only memory (“EEPROM”), flash memory or other memory technologies, compact disc read only memory (“CD ROM”), digital versatile discs (“DVD”), Blu-ray discs (“BD”) or other optical disc storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, solid state drives or other solid state storage devices, or other tangible and / or non-transitory media that can be used to store the desired information. In this regard, the terms “tangible” or “non-transitory” as applied to storage, memory or computer-readable media herein will be understood to exclude only propagating transitory signals per se as a modifier and do not relinquish rights to all standard storage, memory or computer-readable media that do not consist solely of propagating transitory signals per se.

[0064] A computer-readable storage medium may be accessed by one or more local or remote computing devices, such as via an access request, query or other data retrieval protocol, for performing various operations on the information stored by the medium.

[0065] A communication medium typically embodies computer-readable instructions, data structures, program modules or other structured or unstructured data in a data signal such as a modulated data signal, e.g., a carrier wave or other transport mechanism, and includes any information delivery or transport medium. The term “modulated data signal” or signals refers to a signal that has one or more of its characteristics set or changed in such a manner as to encode information in one or more signals. By way of example, and not limitation, a communication medium includes wired media, such as a wired network or direct-wired connection, and wireless media, such as acoustic, RF, infrared and other wireless media.

[0066] Referring again to Figure 10 , an example environment 1000 for implementing aspects of the embodiments described herein includes a computer 1002 that includes a processing unit 1004, a system memory 1006, and a system bus 1008. The system bus 1008 couples system components including, but not limited to, the system memory 1006 to the processing unit 1004. The processing unit 1004 can be any of a variety of commercially available processors. Dual microprocessors and other multiprocessor architectures can also be used as the processing unit 1004.

[0067] The system bus 1008 can be any one of several types of bus structures, which can also be interconnected to a memory bus (with or without a memory controller), a peripheral bus, and a local bus using any one of various commercially available bus architectures. The system memory 1006 includes a ROM 1010 and a RAM 1012. The basic input / output system (“BIOS”) can be stored in non-volatile memories such as ROM, erasable programmable read-only memory (“EPROM”), EEPROM, etc., where the BIOS contains basic routines that help transfer information between components within the computer 1002, such as during startup. The RAM 1012 can also include high-speed RAM, such as static RAM for caching data.

[0068] The computer 1002 also includes an internal hard disk drive (“HDD”) 1014 (e.g., EIDE, SATA), one or more external storage devices 1016 (e.g., a floppy disk drive (“FDD”) 1016, a memory stick or flash drive reader, a memory card reader, etc.), and an optical disc drive 1020 (e.g., which can read from or write to a CD-ROM disc, a DVD, a BD, etc.). Although the internal HDD 1014 is shown as being within the computer 1002, the internal HDD 1014 can also be configured for external use in a suitable chassis (not shown). Additionally, although not shown in the environment 1000, a solid-state drive (“SSD”) can be used in addition to or in place of the HDD 1014. The HDD 1014, one or more external storage devices 1016, and the optical disc drive 1020 can be connected to the system bus 1008 through an HDD interface 1024, an external storage interface 1026, and an optical disc drive interface 1028, respectively. The interface 1024 for external drive implementations can include at least one or both of the universal serial bus (“USB”) and the Institute of Electrical and Electronics Engineers (“IEEE”) 1394 interface technologies. Other external drive connection technologies are within the scope of the embodiments described herein.

[0069] The drives and their associated computer-readable storage media provide non-volatile storage of data, data structures, computer-executable instructions, etc. For the computer 1002, the drives and storage media accommodate the storage of any data in an appropriate digital format. Although the above description of computer-readable storage media relates to the corresponding types of storage devices, those skilled in the art should understand that other types of storage media that are computer-readable, whether currently existing or to be developed in the future, can also be used in the exemplary operating environment, and furthermore, any such storage media can contain computer-executable instructions for performing the methods described herein.

[0070] Multiple program modules may be stored in the drive and in RAM 1012, including an operating system 1030, one or more application programs 1032, other program modules 1034, and program data 1036. All or part of the operating system, applications, modules, and / or data may also be cached in RAM 1012. The systems and methods described herein may be implemented using a variety of commercially available operating systems or combinations of operating systems.

[0071] Computer 1002 may optionally include emulation technology. For example, a hypervisor (not shown) or other intermediary may emulate a hardware environment for operating system 1030, and the emulated hardware may optionally be different from Figure 10 the hardware shown therein. In such an embodiment, operating system 1030 may include a virtual machine (“VM”) among a plurality of VMs hosted at computer 1002. Additionally, operating system 1030 may provide a runtime environment for applications 1032, such as a Java runtime environment or a.NET framework. A runtime environment is a consistent execution environment that allows applications 1032 to run on any operating system that includes the runtime environment. Similarly, operating system 1030 may support containers, and applications 1032 may be in the form of containers, which are lightweight, independent, executable software packages that include, for example, code, runtime, system tools, system libraries, and application settings.

[0072] Furthermore, computer 1002 may be enabled by a security module such as a Trusted Platform Module (“TPM”). For example, for a TPM, a boot component hash is initiated after a boot component, and the result is waited for to match a security value before loading the next boot component. This process may occur at any layer in the code execution stack of computer 1002, e.g., an application at the application execution level or at the operating system (“OS”) kernel level, thus achieving security at any code execution level.

[0073] A user can input commands and information into computer 1002 through one or more wired / wireless input devices, such as keyboard 1038, touch screen 1040, and a pointing device such as mouse 1042. Other input devices (not shown) may include a microphone, an infrared (“IR”) remote control, a radio frequency (“RF”) remote control, or other remote controls, a joystick, a virtual reality controller and / or a virtual reality headset, a game pad, a stylus, an image input device (e.g., a camera), a gesture sensor input device, a visual motion sensor input device, an emotion or face detection device, a biometric input device (e.g., a fingerprint or iris scanner), etc. These and other input devices are typically connected to processing unit 1004 through an input device interface 1044 that can be coupled to system bus 1008, but can also be connected through other interfaces, such as a parallel port, an IEEE 1394 serial port, a game port, a USB port, an IR interface, etc.

[0074] Monitor 1046 or other types of display devices can also be connected to system bus 1008 through an interface such as video adapter 1048. In addition to monitor 1046, a computer typically includes other peripheral output devices (not shown), such as speakers, printers, etc.

[0075] Computer 1002 can operate in a networked environment using a logical connection to one or more remote computers (such as one or more remote computers 1050) through wired and / or wireless communication. One or more remote computers 1050 can be a workstation, a server computer, a router, a personal computer, a portable computer, a microprocessor-based entertainment device, a peer device, or other common network nodes, and typically include many or all of the elements described with respect to computer 1002, although only memory / storage device 1052 is shown for simplicity. The depicted logical connections include a wired / wireless connection to a local area network (“LAN”) 1054 and / or a larger network, such as a wide area network (“WAN”) 1056. Such LAN and WAN networking environments are common in offices and companies and facilitate enterprise-wide computer networks such as intranets, all of which can be connected to a global communication network such as the Internet.

[0076] When used in a LAN network environment, computer 1002 can be connected to local area network 1054 through a wired and / or wireless communication network interface or adapter 1058. Adapter 1058 can facilitate wired or wireless communication to LAN 1054, which can also include a wireless access point (“AP”) disposed thereon for communicating with adapter 1058 in a wireless mode.

[0077] When used in a WAN network environment, computer 1002 may include a modem 1060, or may communicate through other devices for establishing communication on WAN 1056, such as a communication server connected to WAN 1056 through the Internet. Modem 1060 can be an internal or external wired or wireless device, and it can be connected to system bus 1008 via input device interface 1044. In a networked environment, program modules or portions thereof described with respect to computer 1002 may be stored in remote memory / storage device 1052. It can be understood that the network connections shown are examples, and other means for establishing communication links between computers can be used.

[0078] When used in a LAN or WAN networking environment, computer 1002 can access a cloud storage system or other network-based storage systems as a supplement or alternative to external storage device 1016 as described above. Generally, the connection between computer 1002 and the cloud storage system can be established, for example, on LAN 1054 or WAN 1056 through adapter 1058 or modem 1060 respectively. When connecting computer 1002 to an associated cloud storage system, external storage interface 1026 can manage the storage provided by the cloud storage system with the help of adapter 1058 and / or modem 1060, just as it manages other types of external storage. For example, external storage interface 1026 can be configured to provide access to cloud storage sources as if these sources were physically connected to computer 1002.

[0079] Computer 1002 can be operable to communicate with any wireless device or entity operatively arranged in wireless communication, such as printers, scanners, desktop and / or portable computers, portable data assistants, communication satellites, any device or location associated with a wireless detectable tag (e.g., phone booths, newsstands, shelves, etc.), and telephones. This can include wireless fidelity (“Wi-Fi”) and wireless technologies. Thus, the communication can be a predefined structure like a conventional network, or simply an ad hoc communication between at least two devices.

[0080] The foregoing description includes only examples of systems, computer program products, and computer-implemented methods. Of course, it is not possible to describe every conceivable combination of components, products, and / or computer-implemented methods for the purpose of describing the present disclosure, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present disclosure are possible. Additionally, to the extent that the terms "including," "having," "owning," etc. are used in the detailed description, the claims, the appendices, and the drawings, these terms are intended to be inclusive in a manner similar to the way the term "comprising" is interpreted when used as a transitional word in the claims. The description of the various embodiments has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to one of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are chosen to best explain the principles of the embodiments, the practical application, or the technical improvement over technologies found in the marketplace, or to enable other one of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for a quantum circuit, comprising: Controlling quantum gate coupling via the quantum circuit by filtering resonator-induced phase gate signals from signal control lines, where the signal control lines are multiplexed with multiple resonator-induced phase gate signals; and Setting the bandwidth of the filtering resonator via the quantum circuit by adjusting the coupling capacitance between the filtering resonator and the signal control lines, where the filtering resonator filters the resonator-induced phase gate signals from the signal control lines based on frequency according to the bandwidth.

2. The method according to claim 1, wherein, The filtering is performed by a filtering resonator coupled between the signal control lines and a resonator bus.

3. The method according to claim 2, wherein, The resonator bus is a resonator-induced phase gate between multiple superconducting qubits.

4. The method according to any one of claims 1-3, wherein, Via frequency division multiplexing, the multiple resonator-induced phase gate signals are multiplexed onto the signal control lines via a quantum controller, and wherein the filtering is based on the frequency of the resonator-induced phase gate signals.

5. A method for a quantum circuit, comprising: Routing a signal control line to a filtering resonator via the quantum circuit, where multiple resonator-induced phase gate signals are multiplexed onto the signal control line; and Coupling the output of the filtering resonator to a resonator-induced phase gate via the quantum circuit; Via the quantum circuit, setting the coupling capacitance between the filtering resonator and the signal control line, where the filtering resonator selects the resonator-induced phase gate signal from the multiple resonator-induced phase gate signals based on the coupling capacitance.

6. The method according to claim 5, wherein, The output of the filtering resonator is the resonator-induced phase gate signal from the multiple resonator-induced phase gate signals.

7. The method according to claim 6, wherein, The filtering resonator is from multiple filtering resonators, where the resonator-induced phase gate is from multiple resonator-induced phase gates, and wherein the method further comprises: coupling a second output of a second filtering resonator among the multiple filtering resonators to a second resonator-induced phase gate via the quantum circuit, and the second resonator-induced phase gate couples other multiple superconducting qubits.

8. The method according to claim 7, wherein, The second output of the second filtering resonator is the second resonator-induced phase gate signal among the multiple resonator-induced phase gate signals, and wherein the resonator-induced phase gate signal is different from the second resonator-induced phase gate signal.

9. The method according to any one of claims 5-8, wherein, The filtering resonator prohibits a second resonator-induced phase gate signal among the multiple resonator-induced phase gate signals from being transmitted to the resonator-induced phase gate.

10. The method according to any one of claims 5-8, wherein, The multiplexing is frequency division multiplexing, and wherein, the filtering resonator generates the output by filtering the signal control line based on the frequency of the phase gate signal induced by the plurality of resonators.

11. The method according to any one of claims 5-8, further comprising: setting the bandwidth of the filtering resonator via the quantum circuit by adjusting the coupling capacitance between the filtering resonator and the signal control line; and generating the output via the quantum circuit by filtering the resonator-induced phase signal in the plurality of resonator-induced phase gate signals via the filtering resonator.

12. The method according to claim 11, wherein, the filtering resonator resonates the resonator-induced phase gate signal by frequency based on the bandwidth.

13. A system for a quantum circuit, comprising: a resonator bus coupled to a filtering resonator, wherein the filtering resonator outputs a control tone, and the control tone drives the resonator bus according to a plurality of control tones multiplexed onto a quantum gate control line; and a capacitor coupling the filtering resonator to the quantum gate control line, wherein the frequency of the control tone is based on the capacitance of the capacitor.

14. The system according to claim 13, wherein, the system is a multi-qubit circuit quantum electrodynamics system.

15. The system according to claim 13, wherein, the filtering resonator is selected from the group including a band-pass filter and a band-stop filter.

16. The system according to any one of claims 13-15, wherein, the quantum gate control line is multiplexed with a plurality of control tones, and wherein the control tone is from the plurality of control tones.

17. The system according to any one of claims 13-15, wherein, the control tone is a resonator-induced phase gate signal, and the resonator bus is a resonator-induced phase gate.

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