CN115765646B - Signal amplification device, quantum computing system and signal amplification method - Google Patents
Signal amplification device, quantum computing system and signal amplification method Download PDFInfo
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Abstract
The invention provides a signal amplifying device, comprising: a first waveguide configured to split an input optical signal into a first optical signal and a second optical signal; a first signal path and a second signal path coupled to the first waveguide and configured to couple the first optical signal and the second optical signal into the first signal path and the second signal path, respectively, and transmit; the first signal amplifying module and the second signal amplifying module are respectively coupled with the first signal path and the second signal path and are configured to amplify the first optical signal and the second optical signal to generate a first reflection signal and a second reflection signal, and the first reflection signal and the second reflection signal are reflected to the first signal path and the second signal path; and a second waveguide coupled to the first and second signal paths and configured to couple the first and second reflected signals into the second waveguide, the second waveguide outputting a superimposed signal of the first and second reflected signals.
Description
Technical Field
The application relates to the technical field of quantum computing, in particular to a signal amplifying device, a quantum computing system comprising the signal amplifying device and a signal amplifying method using the quantum computing system.
Background
Accurate control and readout of qubits is critical to the implementation of quantum computing techniques, relying on well-designed control and readout circuitry. The signal amplifier plays an important role in superconducting qubit signal reading. Josephson parametric amplifier (Josephson PARAMETRIC AMPLIFIER, JPA) has the characteristics of high gain and near quantum limit noise at the same time, and becomes a key device for current superconducting qubit research and application. JPA is used as the first stage amplification on superconducting qubit read lines, and the amplification performance plays a key role in the read fidelity.
The currently used josephson parametric amplifier is a negative resistance reflective amplifier, i.e. the microwave signal to be amplified firstly enters the parametric amplifier through the 1 port of the circulator, then enters the parametric amplifier after being output through the 2 port, and energy is obtained under the excitation of the pumping signal, and the amplified microwave signal returns to the circulator and is output from the 3 port. The 1 port and the 3 port of the circulator are mutually isolated, so that the separation of input signals and output signals is realized. From the above description, it can be seen that current JPAs need to be used with low temperature circulators, which has become a bottleneck limiting JPA applications. There is an urgent need to develop parametric amplifiers that integrate input-output isolation functions.
Disclosure of Invention
In view of at least one of the drawbacks of the prior art, the present invention provides a signal amplifying device, comprising:
A first waveguide configured to split an input optical signal into a first optical signal and a second optical signal;
a first signal path and a second signal path coupled to the first waveguide and configured to couple the first optical signal and the second optical signal into the first signal path and the second signal path, respectively, and transmit;
The first signal amplifying module and the second signal amplifying module are respectively coupled with the first signal path and the second signal path, are configured to respectively receive the first optical signal and the second optical signal, generate a first reflection signal and a second reflection signal after amplifying, and respectively reflect the first reflection signal and the second reflection signal to the first signal path and the second signal path;
And a second waveguide coupled to the first and second signal paths and configured to couple the first and second reflected signals into the second waveguide, the second waveguide outputting a superimposed signal of the first and second reflected signals.
According to one aspect of the invention, a difference between transmission distances of the first signal path and the second signal path and a quarter wavelength of the input optical signal is less than a preset value.
According to one aspect of the invention, wherein the first waveguide comprises an H-T waveguide comprising a main waveguide having a first port and a second port and a branch waveguide having a third port, the first waveguide configured to:
The input optical signal is coupled from the third port, the first optical signal is coupled from the first port into the first signal path, and the second optical signal is coupled from the second port into the second signal path.
According to one aspect of the invention, wherein the second waveguide comprises an E-T waveguide comprising a main waveguide having a first port and a second port and a branch waveguide having a fourth port, the second waveguide configured to:
The first reflected signal is coupled in from a first port of the E-T waveguide, the second reflected signal is coupled in from a second port of the E-T waveguide, and the superimposed signal is coupled out from a fourth port of the E-T waveguide.
According to one aspect of the invention, the first waveguide and the second waveguide share a main waveguide.
According to one aspect of the invention, wherein the first waveguide and the second waveguide each comprise a substrate integrated waveguide comprising:
a sheet-like medium configured to transmit an optical signal therein;
the metal layer covers the upper surface and the lower surface of the flaky medium;
And the inner wall is provided with a metal layer which is arranged along the edge of the sheet medium and is configured to limit the optical signal to the inside of the sheet medium.
According to one aspect of the present invention, the main waveguide has a first slot on a central axis thereof, and the branch waveguide of the second waveguide has a second slot thereon, the first slot corresponding to the second slot such that the superimposed signal is coupled into the branch waveguide of the second waveguide through the first slot and the second slot.
According to an aspect of the present invention, the signal amplifying device further includes:
An input module coupled to the first waveguide and configured to receive an input optical signal and couple into the first waveguide;
An output module coupled to the second waveguide and configured to couple the superimposed signal out of the second waveguide to the output module.
According to one aspect of the invention, wherein the first signal path, the second signal path, the input module and the output module each comprise a microstrip line structure, the microstrip line structure being located above a sheet-like medium, a lower surface of the sheet-like medium being covered with a metal layer.
According to one aspect of the invention, wherein the first signal path, the second signal path, the input module and the output module each comprise a transition structure to match the microstrip line structure with the first waveguide or the second waveguide.
According to one aspect of the invention, wherein the first signal amplifying module and the second signal amplifying module each comprise:
At least one josephson junction, each josephson junction comprising two superconductors connected by a nanowire for producing a two-level system;
A capacitance connected in parallel with the at least one josephson junction.
The present invention also provides a quantum computing system comprising:
At least one quantum sensor configured to generate a qubit signal;
a signal amplification device as described above, coupled to the quantum sensor, configured to amplify the qubit signal.
The present invention also provides a method of signal amplification using a signal amplification apparatus as described above, comprising:
splitting the input optical signal into a first optical signal and a second optical signal by the first waveguide;
coupling the first optical signal and the second optical signal into the first signal path and the second signal path respectively and transmitting;
The first optical signal and the second optical signal are respectively received through the first signal amplifying module and the second signal amplifying module, and a first reflection signal and a second reflection signal are generated after amplification and respectively reflected to the first signal path and the second signal path;
And coupling the first reflected signal and the second reflected signal into the second waveguide, and outputting a superposition signal of the first reflected signal and the second reflected signal.
One or more embodiments of the present invention provide an input-output isolated signal amplification apparatus, and the signal amplification apparatus is suitable for on-chip integration. The above-described one or more embodiments of the present invention take advantage of the principles of negative resistance reflection, quarter-wavelength phase shifting, and sum and difference path difference of inverted signals of the JPA. Compared with the prior art, the method and the device have the advantages that ferrite devices such as a low-temperature circulator are not needed, the influence of a ferrite strong magnetic field on the quantum bit information flow is eliminated, and therefore the accuracy of bit information reading can be improved. The invention integrates the signal amplifying module and the input/output circuit, greatly improves the integration level and the space utilization rate of devices, saves the low-temperature precious resources of the dilution refrigerator, and has positive effect on increasing multi-bit reading.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it will be apparent that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings by those skilled in the art without departing from the scope of the claimed application.
FIG. 1 illustrates a signal amplifying device provided by an embodiment of the present invention;
FIG. 2A illustrates a first waveguide in a signal amplifying device provided by one embodiment of the present invention;
FIG. 2B shows an electric field distribution in a first waveguide in a signal amplifying device provided by an embodiment of the present invention;
FIG. 3A illustrates a second waveguide in a signal amplifying device provided by an embodiment of the present invention;
FIG. 3B shows an electric field distribution in a second waveguide in a signal amplifying device provided by an embodiment of the present invention;
FIG. 4 illustrates an integrated optical element of a first waveguide and a second waveguide in a signal amplification apparatus provided by one embodiment of the present invention;
FIG. 5A illustrates a first waveguide in a signal amplifying device provided by one embodiment of the present invention;
FIG. 5B illustrates a second waveguide in a signal amplifying device provided by an embodiment of the present invention;
FIG. 6 shows a signal amplifying device provided by an embodiment of the present invention;
FIG. 7A illustrates a signal amplifying device provided by an embodiment of the present invention;
FIG. 7B illustrates a signal amplifying device provided by an embodiment of the present invention;
FIGS. 8A-8B illustrate a first waveguide and its connection lines and components in a signal amplification apparatus according to one embodiment of the present invention;
FIGS. 8C-8D illustrate a second waveguide and its connection lines and components in a signal amplification apparatus according to one embodiment of the present invention;
FIG. 9 illustrates a comparison of microstrip line to substrate integrated waveguide transition optimization before and after in one embodiment of the present invention;
FIG. 10 illustrates a comparison of before and after centerline-aware through-hole optimization in one embodiment of the invention;
FIG. 11 illustrates signal frequencies of a first port, a second port, a third port, and a fourth port in one embodiment of the invention;
FIG. 12 illustrates a quantum computing system provided by an embodiment of the invention;
fig. 13 illustrates a method for signal amplification provided by one embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The foregoing has outlined rather broadly the more detailed description of embodiments of the application in order that the detailed description of the principles and embodiments of the application may be implemented in conjunction with the detailed description of embodiments of the application that follows. Meanwhile, based on the idea of the present application, those skilled in the art can make changes or modifications on the specific embodiments and application scope of the present application, which belong to the protection scope of the present application. In view of the foregoing, this description should not be construed as limiting the application.
In the prior art, in order to realize isolation of input and output signals, a Josephson parametric amplifier (Josephson PARAMETRIC AMPLIFIER, JPA) must be matched with a circulator (or an isolator), the low-temperature circulator is a multiport device, electromagnetic waves can only circulate along a single direction in transmission of the circulator, and signals are isolated when the electromagnetic waves circulate along the opposite direction, and the non-reciprocal property of the circulator and the magnetism of ferrite are utilized. Therefore, the circulator can realize the cyclic transmission of microwave signals and measure the corresponding microwave signals. However, the method of matching the josephson parametric amplifier with the low-temperature circulator has a great limitation. This presents two problems: the circulator is a ferrite device, has a strong magnetic field, can introduce additional uncontrollable factors and causes interference to accurate reading of the qubits. Secondly, the qubit measurement needs to be carried out in a very low temperature environment, and is generally placed in the lowest temperature area inside the dilution refrigerator, and the space of the area is limited. Ferrite annuli have a large volume and can take up valuable resources. The problem of volume occupation is not outstanding when amplifying single-bit signals because a circulator is required to be configured for amplifying the single-bit signals. The problem of multiple circulators being required to amplify multiple bits is very serious and can be a bottleneck limiting the practical use of multiple bits. Thus, there is a great need to overcome the dependence of the input-output signals of the josephson parametric amplifier on the circulators.
In order to solve the problem that the current Josephson parametric amplifier needs to use an additional circulator to isolate input and output signals, the invention provides a signal amplifying device adopting an integrated input and output isolation circuit, thereby improving the integration level of devices, saving low-temperature precious resources of a dilution refrigerator and having positive effect on increasing multi-bit reading.
According to an embodiment of the present invention, as shown in fig. 1, the present invention provides a signal amplifying apparatus 100, including: a first waveguide 110, a first signal path 120 and a second signal path 130, a first signal amplification module 140 and a second signal amplification module 150, and a second waveguide 160. Wherein:
The first waveguide 110 is configured to split an input optical signal into a first optical signal and a second optical signal. The first waveguide 110 includes, for example, an H-T waveguide, which includes a main waveguide and a branch waveguide perpendicular to the main waveguide, whose central axis is parallel to a magnetic field plane of an electromagnetic wave (H10 wave) transmitted in the main waveguide, as shown in fig. 2A. The main waveguide of the H-T waveguide has a first port and a second port, the branch waveguide has a third port, and the transmission characteristic of the H-T waveguide comprises: the electromagnetic wave (such as an input optical signal) coupled in from the third port of the branch waveguide is divided into two electromagnetic wave signals (such as a first optical signal and a second optical signal) with equal amplitude and in phase in the main waveguide, wherein the first optical signal is transmitted to the direction of the first port of the main waveguide, and the second optical signal is transmitted to the direction of the second port of the main waveguide. As shown in fig. 2B, the input optical signal coupled in from the third port of the branch waveguide is the same as the electric field direction of the first optical signal transmitted in the direction of the first port of the main waveguide and the second optical signal transmitted in the direction of the second port of the main waveguide. Those skilled in the art will readily appreciate that the use of an H-T waveguide is only one embodiment of the present invention, and that other waveguide devices capable of performing the above-described splitting function are within the scope of the present invention.
The first and second signal paths 120, 130 are coupled to the first waveguide 110 and configured such that the first and second optical signals are coupled into the first and second signal paths 120, 130, respectively, and transmitted. Taking the example that the first waveguide 110 includes an H-T waveguide, a first port of a main waveguide of the H-T waveguide is coupled to the first signal path 120, so that the first optical signal is coupled from the first port of the main waveguide to the first signal path 120; a second port of the main waveguide of the H-T waveguide is coupled to the second signal path 130 such that a second optical signal is coupled from the second port of the main waveguide into the second signal path 130.
The first signal amplifying module 140 and the second signal amplifying module 150 are coupled to the first signal path 120 and the second signal path 130, respectively, and configured to receive the first optical signal and the second optical signal, respectively, and generate a first reflected signal and a second reflected signal after amplifying, and reflect the first reflected signal and the second reflected signal to the first signal path 120 and the second signal path 130. The first signal amplifying module 140 and the second signal amplifying module 150 have the functions of signal amplifying and negative resistance reflecting, and the first signal amplifying module 140 receives the first optical signal, amplifies the first optical signal and returns the first optical signal to the original path, and enters the first signal path 120 for reverse transmission; the second signal amplifying module 150 receives the second optical signal, amplifies the second optical signal, and returns the second optical signal to the original path, and transmits the second optical signal in the reverse direction through the second signal path 130.
The second waveguide 160 is coupled to the first signal path 120 and the second signal path 130 and configured to couple the first reflected signal and the second reflected signal into the second waveguide 160, and the second waveguide 160 outputs a superimposed signal of the first reflected signal and the second reflected signal. The second waveguide 160 includes, for example, an E-T waveguide including a main waveguide and a branch waveguide perpendicular to the main waveguide, whose central axis is parallel to an electric field plane of an electromagnetic wave (H10 wave) transmitted in the main waveguide, as shown in fig. 3A. The main waveguide of the E-T waveguide has a first port and a second port, the branch waveguide has a fourth port, and the transmission characteristic of the E-T waveguide comprises: electromagnetic waves (e.g., a first optical signal) coupled from a first port of its main waveguide and electromagnetic waves (e.g., a second optical signal) coupled from a second port of its main waveguide form a standing wave in its main waveguide, and the standing wave in the main waveguide of the E-T waveguide is coupled into its branch waveguide only when there is a magnetic field component on the first symmetry plane, on a first symmetry plane of the electromagnetic waves coupled from the first port of its main waveguide and the electromagnetic waves coupled from the second port of its main waveguide, which is opposite to the opening direction of the branch waveguide of the E-T waveguide. As shown in fig. 3B, the optical signals coupled from the first port and the second port of the main waveguide of the E-T waveguide are coupled into the branch waveguide of the E-T waveguide in opposite electric field directions, and the electric field directions of the optical signals in the branch waveguide are different from the electric field directions of the optical signals in the main waveguide.
Similarly, with the first waveguide 110, since the central axis of the branching waveguide of the H-T waveguide is parallel to the magnetic field plane of the electromagnetic wave transmitted in the main waveguide, only when the electromagnetic wave coupled in from the first port of the main waveguide thereof and the electromagnetic wave coupled in from the second port of the main waveguide thereof have an electric field component on the second symmetry plane (the second symmetry plane is opposite to the opening direction of the branching waveguide of the H-T waveguide), the standing wave in the main waveguide of the H-T waveguide is coupled in to the branching waveguide thereof. Therefore, the isolation function of input and output can be realized as long as the energy distribution on the first symmetrical plane and the second symmetrical plane (the section facing the opening direction of the E-T type branch waveguide and the section facing the opening direction of the H-T type branch waveguide, which are mutually perpendicular and respectively correspond to the magnetic field vibration plane and the electric field vibration plane) of the first optical signal and the second optical signal can be adjusted. Those skilled in the art will readily appreciate that the use of an E-T waveguide is only one embodiment of the present invention, and that other waveguide devices capable of implementing the input/output isolation function described above are within the scope of the present invention.
According to an embodiment of the present invention, in the signal amplifying device 100 provided by the present invention, a difference between transmission distances of the first signal path 120 and the second signal path 130 and a quarter wavelength of the input optical signal is smaller than a preset value. That is, the difference (optical path difference) between the transmission distances of the first signal path 120 and the second signal path 130 is equal to or close to a quarter wavelength of the input optical signal, and by setting the difference between the transmission distances of the first signal path 120 and the second signal path 130, the signal isolation between the branching waveguide of the H-T waveguide and the branching waveguide of the E-T waveguide can be improved, thereby more precisely realizing the isolation function of the input and output signals. In one embodiment of the present invention, an input optical signal coupled in from a third port of a branching waveguide of the H-T waveguide is split into a first optical signal and a second optical signal with equal amplitude and in phase in the main waveguide, wherein the first optical signal is transmitted toward the first port of the main waveguide and is coupled into the first signal path 120; the second optical signal is transmitted in the direction of the second port of the main waveguide and coupled into the second signal path 130. The first optical signal reaches the first signal amplifying module 140, and forms a first reflected signal after being amplified, and the first reflected signal is reflected back to the first signal path 120; the second optical signal reaches the second signal amplifying module 150, and is amplified to form a second reflected signal, which is reflected back to the second signal path 130. When the first reflected signal and the second reflected signal are coupled into the main waveguide of the E-T waveguide (the first reflected signal is coupled from the first port of the main waveguide, and the second reflected signal is coupled from the second port of the main waveguide), compared with the first optical signal and the second optical signal which are divided into equal-amplitude and same-phase in the main waveguide, the transmission distance of the two signals is different by one half wavelength, so the phase difference between the first reflected signal and the second reflected signal is 180 degrees. According to the transmission characteristics of the H-T waveguide and the E-T waveguide, the first reflected signal and the second reflected signal have a magnetic field component (typically, the magnetic field component is the largest) on the first symmetry plane, and the superimposed signal thereof is coupled into the branch waveguide of the E-T waveguide; the first reflected signal and the second reflected signal have no (or minimal) electric field component on the second symmetry plane, and no superimposed signal is coupled out to the branching waveguide of the H-T waveguide.
In accordance with one embodiment of the present invention, as shown in fig. 4, in the signal amplifying device 100, the first waveguide 110 includes the H-T waveguide as described above, and the second waveguide 160 includes the E-T waveguide as described above, and the first waveguide 110 and the second waveguide 160 share a portion of the main waveguide. I.e. the first waveguide 110 and the second waveguide 160 are integrated into a matched double-T structure.
According to one embodiment of the present invention, as shown in fig. 5A and 5B, the first waveguide 110 and the second waveguide 160 each include a substrate integrated waveguide including:
a sheet-like medium configured to cause transmission of an optical signal in the medium.
And the metal layer is covered on the upper surface and the lower surface of the medium.
And the inner wall is provided with a metal layer which is arranged along the edge of the sheet medium and is configured to limit the optical signal to the inside of the sheet medium.
And covering the upper surface and the lower surface of the sheet medium with metal layers, and arranging through holes with the metal layers on the inner walls along the edges of the sheet medium, so that the substrate integrated waveguide has transmission characteristics similar to those of a metal rectangular waveguide.
According to an embodiment of the present invention, as shown in fig. 5A and 5B, in the signal amplifying apparatus 100 provided by the present invention, a first slot is formed on a central axis of a main waveguide shared by the first waveguide 110 and the second waveguide 160, and a second slot (not shown in the drawings) is formed on a branch waveguide of the second waveguide 160, where the first slot corresponds to the second slot, so that the superimposed signal is coupled into the branch waveguide of the second waveguide 160 through the first slot and the second slot.
According to one embodiment of the present invention, the upper surface of the first waveguide 110 is in contact with the lower surface of the second waveguide 160 and is coplanar and grooved at the interface of the two. The first waveguide 110 is the above-mentioned H-T type waveguide, and has upper and lower surfaces covered with metal layers, and a through hole is opened in a region covered with the metal layers, and the inner wall of the through hole has the metal layer to electrically connect the upper and lower surfaces. The metal vias on the first waveguide 110 are arranged in two parallel rows. The region of the upper surface of the first waveguide 110 covered with the metal layer is bilaterally symmetrical with respect to the third port center line of the branched waveguide of the H-T waveguide. The upper surface of the first waveguide 110 has a slot, the end of the slot has a through hole, and the slot and the end through hole are located on the center line of the third port, and the end through hole is electrically connected to the upper and lower surfaces. The second waveguide 160 is the E-T type waveguide described above, and has upper and lower surfaces covered with metal layers, and a through hole is formed in a region covered with the metal layers, and the metal layers are provided on the inner wall of the through hole to electrically connect the upper and lower surfaces. The metal vias on the second waveguide 160 are distributed in a U-shape. The aperture and spacing of the metal vias in the first waveguide 110 and the second waveguide 160 are determined based on the operating frequency (input optical signal frequency) and the dielectric constant of the sheet medium.
According to an embodiment of the present invention, as shown in fig. 6, the signal amplifying apparatus 100 further includes: an input module 170 and an output module 180. Wherein:
The input module 170 is coupled to the first waveguide 110 and is configured to receive an input optical signal and couple into the first waveguide 110.
The output module 180 is coupled to the second waveguide 160 and configured to couple the superimposed signal out of the second waveguide 160 to the output module 180.
The input optical signal is received and shaped by the input module 170 and coupled into the first waveguide 110, the superimposed signal is coupled out of the second waveguide 160, and shaped and transmitted to the reading or manipulation circuit, or the next-stage amplifying device, by the output module 180. In the signal amplifying device 100 according to an embodiment of the present invention, the input module 170 and the output module 180 are implemented in the form of a microstrip line structure or a coplanar waveguide.
In the signal amplifying device 100 according to an embodiment of the present invention, the first signal path 120, the second signal path 130, the input module 170, and the output module 180 each include a microstrip line structure that is located on a sheet-shaped medium, and a lower surface of the sheet-shaped medium is covered with a metal layer.
As shown in fig. 7A and 7B, in the signal amplifying device 100, the first waveguide 110 includes an H-T waveguide, the second waveguide 160 includes an E-T waveguide, and the first waveguide 110 and the second waveguide 160 share a main waveguide portion, thereby forming a structure matching a double T. Microstrip line structures are connected to the first port, the second port, the third port and the fourth port of the main waveguide of the H-T waveguide, and used as the first signal path 120, the second signal path 130, the input module 170 and the output module 180, respectively.
The third port of the H-T waveguide and the fourth port of the E-T waveguide serve as the input and output ports for the signal to be amplified, and the first port and the second port of the H-T waveguide serve as the ports for connecting the first signal amplifying module 140 and the second signal amplifying module 150. The four ports are each connected to the outside or other components in the form of microstrip lines.
According to an embodiment of the present invention, in the signal amplifying device 100, the first signal path 120, the second signal path 130, the input module 170 and the output module 180 each include a transition structure for matching the microstrip line structure with the first waveguide 110 or the second waveguide 160.
In the signal amplifying device 100 according to an embodiment of the present invention, the first signal path 120, the second signal path 130, the input module 170, and the output module 180 are all connected to the first waveguide 110 or the second waveguide 160 through a transition structure. The transition structure can adopt a microstrip line structure to enable the microstrip line structure of the input/output port or the transmission path to transition towards the substrate integrated waveguide, namely, a microstrip line structure which is wider than the microstrip line structure of the input/output port or the transmission path is adopted as an optical transition path, so that the matching of the input/output port or the transmission path and the substrate integrated waveguide is realized. In general, the size of the input/output port or the signal transmission channel is fixed, and the matching of the interface of the microstrip line structure and the substrate integrated waveguide can be adjusted by adjusting the size of the transition structure.
In accordance with one embodiment of the present invention, in signal amplification apparatus 100, first signal amplification module 140 and second signal amplification module 150 employ a josephson parametric amplifier comprising:
At least one josephson junction, each josephson junction comprising two superconductors connected by a nanowire for creating a two-level system.
A capacitance connected in parallel with the at least one josephson junction.
The weak signal output by the quantum chip carries quantum bit information. When the signal enters the parametric amplifier, the pumping energy is obtained in an inductance-capacitance resonator (LC harmonic oscillator) formed by a capacitance and a Josephson superconducting interference ring, and then amplified and reflected back to the signal input end for output. Wherein the Josephson superconducting interference ring is optionally composed of two Josephson junctions connected in parallel, and the capacitor is selected from parallel plate capacitor or distributed capacitor. The dielectric of the parallel plate capacitor may be oxide, nitride or the like, or may be air.
The input-amplifying-reflecting characteristics of the josephson parametric amplifier can be applied to the signal amplifying device 100 provided by the present invention. The invention uses two identical josephson parametric amplifiers as single port devices, when the first optical signal or the second optical signal is input to the josephson parametric amplifier and reflected, the amplitude of the signal increases while the phase remains unchanged.
In the signal amplifying device 100 provided by the invention, two josephson parametric amplifiers are placed asymmetrically, i.e. the distance between the first signal amplifying module 140 and the first waveguide 110 is different from the distance between the second signal amplifying module 150 and the first waveguide 110, and the difference is equal to or close to 1/4 of the wavelength (working wavelength) of the input optical signal.
In some embodiments, to increase the operating bandwidth and gain of the parametric amplifier circuit, an impedance matcher may be connected to the signal input of the josephson parametric amplifier.
When an H-T waveguide is employed as the first waveguide 110, an E-T waveguide is employed as the second waveguide 160, or a matched double T is employed as an integrated optical element of the first waveguide 110 and the second waveguide 160 in some embodiments, the first signal amplification module 140 and the second signal amplification module 150 are also employed as matched loads of the first waveguide 110 and the second waveguide 160.
One or more embodiments of the present invention provide an input-output isolated signal amplification apparatus, and the signal amplification apparatus is suitable for on-chip integration. The above-described one or more embodiments of the present invention take advantage of the principles of negative resistance reflection, quarter-wavelength phase shifting, and sum and difference path difference of inverted signals of the JPA. Compared with the prior art, the method and the device have the advantages that ferrite devices such as a low-temperature circulator are not needed, the influence of a ferrite strong magnetic field on the quantum bit information flow is eliminated, and therefore the accuracy of bit information reading can be improved. The invention integrates the signal amplifying module and the input/output circuit, greatly improves the integration level and the space utilization rate of devices, saves the low-temperature precious resources of the dilution refrigerator, and has positive effect on increasing multi-bit reading.
The signal amplifying device provided by the invention has the advantages of clear principle, clear structure and simpler preparation process. The specific parameters required for the preparation of the signal amplifying device are described below by means of a specific embodiment.
According to one embodiment of the invention, shown in fig. 8A-8D, the matrix material (sheet dielectric material) of the isolated input-output components 1 and 2 (wherein component 1 comprises a first waveguide 110 and an input module 170 and component 2 comprises a second waveguide 160 and an output module 180) is selected to be Roger RT5880, which has a dielectric constant of 2.2 and a thickness of 0.5mm. When the designed working frequency is 5.5GHz, the width W_ms=1.44 mm and the height of the microstrip line are 0.1mm, and the characteristic impedance of the microstrip line under the parameter is about 50 ohms. The width l_u=35 mm, the distance l_uh=32 mm between two rows of through holes, the diameter d_hole=1 mm, the distance d_p=1.5 mm between adjacent through holes of the components 1 and 2 are set, and the substrate integrated waveguide can only transmit TE10 modes and higher order modes under the parameter. In order to achieve good matching of the microstrip line and the substrate integrated waveguide and reduce interface reflection, the width W_t=2 mm and the length L_t=12.8 mm of the transition section of the microstrip line and the substrate integrated waveguide are set.
As shown in fig. 9, the transmission characteristics of the microstrip line and the substrate integrated waveguide are significantly improved after the size of the transition section is optimized (fig. 9 is a front-back comparison chart). Where the horizontal axis is signal frequency and the vertical axis is signal amplitude, "S21" represents port 1 to port 2 transmission and "S11" represents port 1 echo.
The component 1 is of a T-shaped structure, signals are input from a T main port (port 1), then the signals are decomposed into two signals with equal amplitude and same phase, and the two signals flow out from T branch ports (ports 2 and 3) respectively. A metal through hole is formed at the center line of the main port 1, so that the main port is inductively matched with the branch port, and the transmission characteristic is improved.
As shown in fig. 10, the transmission characteristics of the optimized center line through hole positions (l_hole=13.7mm, d_hole=1 mm) are compared front and back. Where the horizontal axis is signal frequency and the vertical axis is signal amplitude, "S21" represents port 1 transmitting to port 2 ("S31", "S41" are the same), and "S11" represents the echo of port 1.
The port 2 and the port 3 are respectively connected with a parametric amplifying circuit. The capacitance value c=4pf of the parametric amplifier is designed, josephson junction resistance r=70Ω. The JPA at this parameter can achieve a large amplification gain at 5.5GHz frequency. The signals flowing out from the ports 2 and 3 are reflected back after parametric amplification, and become signals flowing in from the ports 2 and 3. Since the microstrip line lengths of the port 2 and the port 3 differ by a quarter wavelength (5.5 GHz corresponds to wavelength λ/4=13.6 mm), the phase difference of the incoming signals is 180 °, and according to the transmission characteristics of the T-shaped waveguide, the electric fields of the two waves are opposite to each other at the main port, and the output of the main port (port 1) is minimum. The upper surface of the component 1 is grooved at a position along the central line of the port 1, the length L_slot=20 mm and the width W_slot=1 mm are the same, and the distance from the grooving starting point to the through hole of the central line of the port 1 is 1mm. Since the slot opening cuts the power line on the upper surface of the assembly 1, electromagnetic energy is emitted from the slot location into the assembly 2.
The assembly 2 is located at the upper part of the assembly 1, and the lower surface of the assembly 2 is in contact with the upper surface of the assembly 1. The lower surface of the component 2 is also grooved, at a distance d slot=2 mm from the array of through holes, and aligned with the grooves of the upper surface of the component 1. Electromagnetic signals emitted from the assembly 1 enter the assembly 2 and sequentially pass through the substrate integrated waveguide, the transition section and the microstrip line to flow out of a main port (port 4) of the assembly 2.
When the final signal is input from the port 1, the HFSS simulation obtains S parameters of four ports as shown in fig. 11, wherein the horizontal axis is the signal frequency, the vertical axis is the amplitude of the signal, "S21" represents the transmission from the port 1 to the port 2 ("S31", "S41" are the same), and "S11" represents the echo of the port 1, as shown in fig. 11: insertion losses S21 and S31 are about-3 dB in the frequency range of 4 to 6 GHz; in the frequency range of 5-5.7 GHz, the return loss is > -15dB; in the frequency range of 4-6 GHz, the isolation between the port 1 and the port 4 is more than 20dB. The signal input from port 1 enters the parametric amplifier through port 2 and port 3, respectively, and the return signal phase difference=180° because the waveguide path lengths of port 2 and port 3 differ by λ/4. At this time, the return signal is output from the port 4, and the port 1 is not output, so that the input/output isolation of the signal with amplification is realized.
According to one embodiment of the present invention, as shown in fig. 12, the present invention also provides a quantum computing system 200 comprising at least one quantum sensor 210 and the signal amplifying device 100 described above. Wherein:
the at least one quantum sensor 210 is configured to generate a qubit signal.
The signal amplification device 100 is coupled to the quantum sensor 210 and is configured to amplify the qubit signal.
According to an embodiment of the present invention, as shown in fig. 13, the present invention also provides a method 10 for signal amplification using the signal amplification apparatus 100 as described above, comprising steps S101 to S104. Wherein:
In step S101, the input optical signal is split into a first optical signal and a second optical signal by the first waveguide.
In step S102, the first optical signal and the second optical signal are coupled into the first signal path and the second signal path, respectively, and transmitted.
In step S103, the first optical signal and the second optical signal are received by the first signal amplifying module and the second signal amplifying module, amplified, and then a first reflected signal and a second reflected signal are generated and reflected to the first signal path and the second signal path.
In step S104, the first reflected signal and the second reflected signal are coupled into the second waveguide, and a superimposed signal of the first reflected signal and the second reflected signal is output through the second waveguide.
In the above-mentioned one or more embodiments of the present invention, the description of the optical signal/optical wave signal is used to illustrate the technical solution and the principle of the present invention, and those skilled in the art will readily understand that the electromagnetic wave signal capable of being transmitted in the waveguide may be applied to the present invention. Among these, the above-described one or more embodiments of the present invention may employ a microwave signal as a processing object of the signal amplifying device.
The qubits referred to in the present invention include information carriers having 0 state, 1 state and superposition state.
Claims (13)
1. A signal amplifying apparatus, comprising:
A first waveguide configured to split an input optical signal into a first optical signal and a second optical signal;
a first signal path and a second signal path coupled to the first waveguide and configured to couple the first optical signal and the second optical signal into the first signal path and the second signal path, respectively, and transmit;
The first signal amplifying module and the second signal amplifying module are respectively coupled with the first signal path and the second signal path, are configured to respectively receive the first optical signal and the second optical signal, generate a first reflection signal and a second reflection signal after amplifying, and respectively reflect the first reflection signal and the second reflection signal to the first signal path and the second signal path;
And a second waveguide coupled to the first and second signal paths and configured to couple the first and second reflected signals into the second waveguide, the second waveguide outputting a superimposed signal of the first and second reflected signals.
2. The signal amplifying device of claim 1, wherein a difference between transmission distances of the first signal path and the second signal path and a quarter wavelength of the input optical signal is less than a preset value.
3. The signal amplifying device of claim 1 or 2, wherein the first waveguide comprises an H-T waveguide comprising a main waveguide having a first port and a second port and a branch waveguide having a third port, the first waveguide configured to:
The input optical signal is coupled from the third port, the first optical signal is coupled from the first port into the first signal path, and the second optical signal is coupled from the second port into the second signal path.
4. The signal amplifying device of claim 3, wherein the second waveguide comprises an E-T waveguide comprising a main waveguide having a first port and a second port and a branch waveguide having a fourth port, the second waveguide configured to:
The first reflected signal is coupled in from a first port of the E-T waveguide, the second reflected signal is coupled in from a second port of the E-T waveguide, and the superimposed signal is coupled out from a fourth port of the E-T waveguide.
5. The signal amplifying device of claim 4, wherein the first waveguide and the second waveguide share a main waveguide.
6. The signal amplifying device of claim 1 or 2, wherein the first waveguide and the second waveguide each comprise a substrate integrated waveguide comprising:
a sheet-like medium configured to transmit an optical signal therein;
the metal layer covers the upper surface and the lower surface of the flaky medium;
And the inner wall is provided with a metal layer which is arranged along the edge of the sheet medium and is configured to limit the optical signal to the inside of the sheet medium.
7. The signal amplifying device of claim 5, wherein the main waveguide has a first slot on a central axis thereof and the branch waveguide of the second waveguide has a second slot thereon, the first slot corresponding to the second slot such that the superimposed signal is coupled into the branch waveguide of the second waveguide through the first slot and the second slot.
8. The signal amplifying device according to claim 1 or 2, further comprising:
An input module coupled to the first waveguide and configured to receive an input optical signal and couple into the first waveguide;
An output module coupled to the second waveguide and configured to couple the superimposed signal out of the second waveguide to the output module.
9. The signal amplifying device of claim 8, wherein the first signal path, the second signal path, the input module, and the output module each comprise a microstrip line structure that is located above a sheet-like medium, a lower surface of which is covered with a metal layer.
10. The signal amplifying device of claim 9, wherein the first signal path, the second signal path, the input module, and the output module each comprise a transition structure to match the microstrip line structure with the first waveguide or the second waveguide.
11. The signal amplifying device according to claim 1 or 2, wherein the first signal amplifying module and the second signal amplifying module each include:
At least one josephson junction, each josephson junction comprising two superconductors connected by a nanowire for producing a two-level system;
A capacitance connected in parallel with the at least one josephson junction.
12. A quantum computing system, comprising:
At least one quantum sensor configured to generate a qubit signal;
The signal amplification apparatus of any of claims 1-11, coupled to the quantum sensor, configured to amplify the qubit signal.
13. A method of signal amplification using the signal amplification apparatus of any one of claims 1-11, comprising:
splitting the input optical signal into a first optical signal and a second optical signal by the first waveguide;
coupling the first optical signal and the second optical signal into the first signal path and the second signal path respectively and transmitting;
The first optical signal and the second optical signal are respectively received through the first signal amplifying module and the second signal amplifying module, and a first reflection signal and a second reflection signal are generated after amplification and respectively reflected to the first signal path and the second signal path;
And coupling the first reflected signal and the second reflected signal into the second waveguide, and outputting a superposition signal of the first reflected signal and the second reflected signal through the second waveguide.
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| CN109327190A (en) * | 2018-09-29 | 2019-02-12 | 华东计算技术研究所（中国电子科技集团公司第三十二研究所） | Multi-quantum bit regulation and control reading device |
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| CN110120792B (en) * | 2019-06-17 | 2024-07-16 | 本源量子计算科技（合肥）股份有限公司 | Quantum parametric amplifier |
| EP4035093A1 (en) * | 2019-09-24 | 2022-08-03 | Google LLC | Multiplexed readout system |
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| CN109327190A (en) * | 2018-09-29 | 2019-02-12 | 华东计算技术研究所（中国电子科技集团公司第三十二研究所） | Multi-quantum bit regulation and control reading device |
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