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

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This patent describes a method for operating a quantum circuit that includes two qubits with different frequencies, which are coupled using a special device called a coupler. The invention involves sending a specific type of signal (cross-resonance pulse) to one of the qubits, where the signal's amplitude is carefully selected to minimize phase errors in operations between the two qubits. The level of unwanted interaction (ZZ-interaction) between the qubits is measured with high precision, allowing for the adjustment of the system to achieve highly reliable two-qubit logic operations.

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• Quantum computing systems that require precise two-qubit gate operations
• Development of scalable quantum processors with low error rates
• Implementation in quantum algorithms that are sensitive to gate fidelity
• Quantum error correction schemes needing high-fidelity entangling operations

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly reduces phase errors between coupled qubits, leading to more reliable quantum operations
• Allows for precise measurement and correction of unwanted interactions between qubits
• Enables higher fidelity in two-qubit gate operations, which is essential for practical quantum computing
• Facilitates the development of more scalable and error-resistant quantum computers

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Patent Abstract

The invention relates to a method for operating a circuit with a first qubit (7) and a second qubit (3), wherein the circuit is configured such that the frequency of the first qubit (7) differs from the frequency of the second qubit (3), with a coupler (4) that couples the first qubit (7) and the second qubit (3), wherein a cross-resonance pulse is sent to the first qubit (7), wherein the amplitude of the cross-resonance pulse is selected such that the two-qubit phase error is minimal in magnitude or at least substantially minimal. The two-qubit phase error is determined by measurement of the qubit Hamiltonian value and measurement of the coupling strength of the ZZ interaction in kilohertz precision. By means of the invention, a high two-qubit gate fidelity can be achieved.