Method for Operating a Circuit Having a First and a Second Qubit

Simple SummaryContent extracted from patent full text and abstract with AI.

This patent describes a method for operating a quantum circuit with two qubits of differing frequencies that are coupled together. By carefully selecting the amplitude of a cross-resonance microwave pulse sent to one qubit, the method can minimize or eliminate phase errors between the two qubits during quantum gate operations, such as CNOT gates. This improves the accuracy and reliability of two-qubit gates by compensating for unwanted interactions (specifically, ZZ-type interactions) that occur in superconducting qubits like Transmons and capacitively shunted flux qubits (CSFQ).

Use CasesContent extracted from patent full text and abstract with AI.

• Increasing the fidelity of quantum gate operations in superconducting quantum computers.
• Optimizing quantum circuits for quantum computing hardware manufacturers.
• Reducing error rates in multi-qubit quantum algorithms, leading to more reliable execution of quantum algorithms.
• Enabling better scaling of quantum processors by managing crosstalk and phase errors in qubit arrays.
• Improving calibration protocols for quantum devices in laboratory and production environments.

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly reduces or eliminates two-qubit phase errors caused by cross-resonance and ZZ coupling.
• Enables higher fidelity (accuracy) in two-qubit quantum gates, which are critical for quantum computation.
• Applicable to various types of superconducting qubits, including Transmons and CSFQs, increasing its versatility.
• Allows in-situ, experimentally tunable calibration of gate parameters to adapt to hardware variations.
• Helps mitigate a fundamental source of error in practical quantum computers, improving their overall performance and reliability.

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Patent Abstract

The invention relates to a method for operating a circuit having a first qubit (7) and a second qubit (3), which circuit is designed so that the frequency of the first qubit (7) differs from the frequency of the second qubit (3), and having a coupler (4) which couples the first qubit (7) and the second qubit (3), a cross-resonance pulse being transmitted to the first qubit (7), and the amplitude of the cross-resonance pulse being selected so that the two-qubit phase error is minimal or at least substantially minimal in terms of amount. The two-qubit phase error is determined by measuring the qubit Hamiltonian value and measuring the coupling strength of the ZZ interaction in kilohertz precision. A high two-qubit gate fidelity can be achieved by the invention.