KR-102964762-B1 - Adjustable quantum coupler that facilitates quantum gates between qubits

KR102964762B1KR 102964762 B1KR102964762 B1KR 102964762B1KR-102964762-B1

Abstract

Devices and/or computer-implemented methods are provided for facilitating quantum gates between qubits using an adjustable coupler and a capacitor device. According to one embodiment, the quantum coupler device may include an adjustable coupler coupled between terminals of the same polarity of a first qubit and a second qubit, said adjustable coupler is configured to control a first coupling between the first qubit and the second qubit. The quantum coupler device may further include a capacitor device coupled to terminals of opposite polarity of the first qubit and the second qubit, said capacitor device is configured to provide a second coupling that is opposite in sign to the first coupling.

Inventors

스티릭, 지리
언더우드, 데빈
자크, 데이비드
스테펜, 마티아스

Assignees

인터내셔널 비지네스 머신즈 코포레이션

Dates

Publication Date: 20260513
Application Date: 20210615
Priority Date: 20200624

Claims (20)

In a quantum coupler device, the device is A tunable coupler coupled between terminals of the same polarity of a first qubit and a second qubit - said tunable coupler is configured to control a first coupling between said first qubit and the second qubit - ; and A capacitor device coupled to terminals of opposite polarity of the first qubit and the second qubit, wherein the capacitor device is configured to provide a second coupling opposite in sign to the first coupling based on the resonant frequency of the adjustable coupler which is smaller than the resonant frequency of both the first qubit and the second qubit. Quantum coupler device.
In claim 1, the adjustable coupler is configured to control the first coupling and the capacitor device is configured to provide the second coupling to eliminate coherent rotations between the first qubit and the second qubit, thereby Reduction of quantum gate errors associated with at least one of the first qubit or the second qubit; Increase in speed of a quantum gate including the first qubit and the second qubit; Improvement of the performance of a quantum processor including the above-mentioned quantum coupler device; and Improvement of the fidelity of the quantum processor including the quantum coupler device facilitating at least one of Quantum coupler device.
In claim 1, the adjustable coupler comprises at least one of a flux-tunable coupler, an adjustable coupler qubit, a flux-tunable coupler qubit, an adjustable qubit, an adjustable bus, and a flux-tunable qubit bus. Quantum coupler device.
In any one of claims 1 to 3, at least one of the first qubit and the second qubit comprises at least one of a fixed frequency qubit, an adjustable qubit, a transmon qubit, a fixed frequency transmon qubit, and an adjustable transmon qubit. Quantum coupler device.
In any one of claims 1 to 3, the capacitor device comprises at least one of a differential capacitor and a bypass capacitor. Quantum coupler device.
In a computer-implemented method of quantum coupling, the method is: A step of providing an adjustable coupling between terminals of the same polarity of a first qubit and a second qubit by a system operably coupled to a processor; The step of providing capacitive coupling between terminals of opposite polarity of the first qubit and the second qubit by the above system; and The above system includes the step of adjusting the resonant frequency associated with the adjustable coupling, and The above capacitive coupling creates a coupling that cancels the tunable coupling when the resonant frequency associated with the tunable coupling is lower than the resonant frequency of both the first qubit and the second qubit. Computer-implemented method.
In paragraph 6, the above method is: The system further comprises the step of decoupling the first qubit from the second qubit based on a coupling that cancels the adjustable coupling when the resonant frequency associated with the adjustable coupling is smaller than the resonant frequency of both the first qubit and the second qubit. Computer-implemented method.
In paragraph 6, the above method is: By further including the step of eliminating consistent rotations in at least one of the first qubit or the second qubit based on a coupling that cancels the adjustable coupling when the resonant frequency associated with the adjustable coupling is smaller than the resonant frequency of both the first qubit and the second qubit, the system Reduction of quantum gate errors associated with at least one of the first qubit or the second qubit; Increase in speed of a quantum gate including the first qubit and the second qubit; Improvement of quantum processor performance; and Improvement of the fidelity of the above quantum processor facilitating at least one of Computer-implemented method.
In any one of claims 6 to 8, at least one of the first qubit and the second qubit comprises at least one of a fixed frequency qubit, an adjustable qubit, a transmon qubit, a fixed frequency transmon qubit, and an adjustable transmon qubit. Computer-implemented method.
In a quantum coupler device, the device is: An adjustable coupler coupled between the first qubit and the second qubit; and It includes a capacitor device coupled between the first qubit and the second qubit, The capacitor device generates a coupling with a sign opposite to the coupling from the adjustable coupler based on the fact that the resonant frequency of the adjustable coupler is smaller than the resonant frequency of both the first qubit and the second qubit. Quantum coupler device.
In claim 10, the capacitor device comprises a first terminal and a second terminal, the first terminal and the second terminal are cross-coupled between the first qubit and the second qubit, and the adjustable coupler is directly coupled between the first qubit and the second qubit. Quantum coupler device.
In paragraph 10, the adjustable coupler is connected between terminals of the same polarity of the first qubit and the second qubit, and the adjustable coupler is configured to control the coupling between the first qubit and the second qubit. Quantum coupler device.
In any one of paragraphs 10 through 12, The above adjustable coupler is coupled between terminals of the same polarity of the first qubit and the second qubit; The above-mentioned adjustable coupler is configured to control a first coupling between the first qubit and the second qubit; The capacitor device is coupled to terminals of opposite polarity of the first qubit and the second qubit; and The capacitor device is configured to provide a second coupling having the opposite sign to the first coupling. Quantum coupler device.
In paragraph 13, the adjustable coupler is configured to control the first coupling, and the capacitor device is configured to provide the second coupling to eliminate coherent rotations between the first qubit and the second qubit, thereby Reduction of quantum gate errors associated with at least one of the first qubit or the second qubit; Increase in speed of a quantum gate including the first qubit and the second qubit; Improvement of the performance of a quantum processor including the above-mentioned quantum coupler device; and Facilitating at least one of the improvements in fidelity of a quantum processor including the above-mentioned quantum coupler device Quantum coupler device.
In any one of claims 10 to 12, the adjustable coupler comprises at least one of a flux adjustable coupler, an adjustable coupler qubit, a flux adjustable coupler qubit, an adjustable qubit, an adjustable bus, and a flux adjustable qubit bus. Quantum coupler device.
In any one of claims 10 to 12, at least one of the first qubit or the second qubit comprises at least one of a fixed frequency qubit, an adjustable qubit, a transmon qubit, a fixed frequency transmon qubit, and an adjustable transmon qubit. Quantum coupler device.
In any one of claims 10 to 12, the capacitor device comprises at least one of a differential capacitor and a bypass capacitor. Quantum coupler device.
In the device, the device is: A first adjustable coupler coupled between terminals of the same polarity of a first qubit and a second qubit - said first adjustable coupler is configured to control a first coupling between the first qubit and the second qubit - ; A first capacitor device coupled to terminals of opposite polarity of the first qubit and the second qubit—the first capacitor device is configured to provide a second coupling opposite in sign to the first coupling, based on the fact that the resonant frequency of the first adjustable coupler is smaller than the resonant frequency of both the first qubit and the second qubit— ; A second adjustable coupler coupled between terminals of the same polarity of the second qubit and the third qubit—the second adjustable coupler is configured to control a third coupling between the second qubit and the third qubit—; and A second capacitor device coupled to terminals of opposite polarity of the second qubit and the third qubit, wherein the second capacitor device is configured to provide a fourth coupling having a sign opposite to that of the third coupling. Device.
In paragraph 18, the second capacitor device provides the fourth coupling based on the fact that the resonant frequency of the second adjustable coupler is smaller than the resonant frequency of both the second qubit and the third qubit. Device.
In paragraph 18, the first adjustable coupler or the second adjustable coupler is configured to control the first coupling or the third coupling, respectively, and the first capacitor device or the second capacitor device is configured to provide the second coupling or the fourth coupling, respectively, to eliminate coherent rotations between the first qubit and the second qubit or between the second qubit and the third qubit, respectively, thereby Reduction of quantum gate errors associated with at least one of the first qubit, the second qubit, and the third qubit; Increase in speed of a quantum gate comprising the first qubit and the second qubit, or the second qubit and the third qubit; Improvement of the performance of a quantum processor including the above device; and Improvement of fidelity of a quantum processor including the above device facilitating at least one of Device.

Description

Adjustable quantum coupler that facilitates quantum gates between qubits [0001] The present invention relates to a quantum coupler, and more specifically, to a quantum coupler that facilitates quantum gates between quantum bits (qubits). [0002] In large-scale quantum computing processors, the nearest neighbor qubits are coupled together to generate the qubit-qubit interactions involved in performing quantum gates. When these interactions are always on, unintentional coherent rotations and/or coherent qubit errors occur in spectator qubits (e.g., adjacent qubits), which lead to gate errors during quantum computations. These coherent rotations and/or coherent qubit errors limit qubit performance and hinder the development of current quantum computing processors. Coupling between adjacent qubits is a major cause of coherent qubit errors, particularly ZZ errors. [0015] FIGS. 1 and 2 illustrate exemplary circuit schematics of non-restrictive devices that can facilitate quantum gates between qubits using adjustable couplers and capacitor devices according to one or more embodiments described herein. [0016] FIGS. 3 and 4 illustrate examples of non-restrictive graphs that can facilitate quantum gates between qubits using adjustable coupler and capacitor devices according to one or more embodiments described herein. [0017] FIGS. 5, 6, 7, 8, and 9 illustrate flow diagrams of exemplary, non-limiting computer-implemented methods that can facilitate quantum gates between qubits using adjustable coupler and capacitor devices according to one or more of the described embodiments. [0018] FIG. 10 illustrates an exemplary block diagram of a non-limiting operating environment in which one or more of the embodiments described herein can be easily implemented. [0019] The following detailed description is for illustrative purposes only and is not intended to limit the use of the embodiments and/or applications or the embodiments. Furthermore, you are not bound by any explicit or implicit information presented in the preceding background or summary sections or detailed description sections. [0020] Now, one or more embodiments are described with reference to the drawings, wherein similar reference numbers are used to refer to elements that are similar in whole. In the following description, for the purposes of explanation, a number of specific details are provided to provide a more complete understanding of one or more embodiments. However, it is evident that in various cases, one or more embodiments may be practiced without these specific details. [0021] Quantum computing is the use of quantum-mechanical phenomena to perform computing and information processing functions. Quantum computing can be viewed in contrast to classical computing, which generally operates on binary values using transistors. That is, while conventional computers can operate on bit values that are 0 or 1, quantum computers operate on quantum bits (qubits) that constitute superpositions of 0 and 1, and can entangle and use interference between multiple quantum bits. [0022] Given the aforementioned problems with respect to the prior art, the present invention may be implemented to provide a solution to these problems in the form of devices and/or computer-implemented methods that can facilitate a quantum gate (e.g., a controlled phase (Cphase) gate) between a first qubit and a second qubit using a quantum coupler device, said quantum coupler device comprises: a tunable coupler coupled between the first qubit and the second qubit; and a capacitor device coupled between the first qubit and the second qubit, said capacitor device creates a coupling opposite in sign to the coupling from the tunable coupler based on the fact that the resonant frequency of the tunable coupler is lower than the resonant frequency of both the first qubit and the second qubit. An advantage of such devices and/or computer-implemented methods is that they can be implemented to improve the speed of the quantum gate (e.g., reduce the time required to complete an operation on the qubit). [0023] In some embodiments, the present invention may be implemented to produce a solution to the aforementioned problem in the form of devices and/or computer-implemented methods that can facilitate a quantum gate (e.g., a Cphase gate) between a first qubit and a second qubit using the quantum coupler device described above, wherein the adjustable coupler is configured to control a first coupling and the capacitor device is configured to provide a second coupling to eliminate coherent rotations between the first qubit and the second qubit. The advantage of such devices and/or computer-implemented methods is that the coupling between the first qubit and the second qubit can be implemented to turn off, thereby eliminating coherent rotations and/or coherent qubit errors in the first qubit and/or the second qubit that cause gate errors during quantum computations. [0024] When it is said that one element is “c