Ancilla Qubit Devices in Superconducting Quantum Processors
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Solution Overview
Problem
In quantum computing architectures, the integration of ancilla qubits with primary qubits is limited by the need for dedicated readout lines and control resources, which increases noise and reduces qubit density on the chip.
Innovation Solution
Implementing ancilla qubits as fixed-frequency devices capacitively coupled to tunable-frequency primary qubits, allowing for information transfer and control via the primary qubits, without direct connections to readout resonators or control lines, and using parametrically-activated gates for two-qubit interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ancilla qubits are integrated with primary qubits using dedicated readout lines and control resources, then qubit functionality and control capability are improved, but noise increases and qubit density decreases
Solution Approach 1:
The patent merges the readout functionality of ancilla qubits with the existing readout infrastructure of primary qubits. By coupling ancilla qubits to the same resonator used for primary qubit readout, the system eliminates dedicated readout lines for ancilla qubits, thereby reducing noise sources while maintaining full readout capability. This combining approach allows multiple qubit types to share common control and measurement resources.
Solution Approach 2:
The patent implements a universal readout resonator that serves both primary qubits and ancilla qubits. This single resonator structure performs multiple functions: reading out states of primary qubits, reading out states of ancilla qubits, and mediating interactions between different qubit types. The resonator is designed to couple with both qubit types simultaneously, creating a multi-functional interface that reduces overall system complexity and noise.
2Adaptability or versatility
If ancilla qubits are integrated with primary qubits using dedicated readout lines and control resources, then qubit functionality is improved, but qubit density on the chip decreases
Solution Approach 1:
The patent merges the readout functionality of ancilla qubits with the existing readout infrastructure of primary qubits. By coupling ancilla qubits to the same resonator used for primary qubit readout, the system eliminates dedicated readout lines for ancilla qubits, thereby reducing noise sources while maintaining full readout capability. This combining approach allows multiple qubit types to share common control and measurement resources.
Solution Approach 2:
The patent implements a universal readout resonator that serves both primary qubits and ancilla qubits. This single resonator structure performs multiple functions: reading out states of primary qubits, reading out states of ancilla qubits, and mediating interactions between different qubit types. The resonator is designed to couple with both qubit types simultaneously, creating a multi-functional interface that reduces overall system complexity and noise.
3Ease of operation
If ancilla qubits are coupled to readout resonators and control lines, then control and measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the readout functionality of ancilla qubits with the existing readout infrastructure of primary qubits. By coupling ancilla qubits to the same resonator used for primary qubit readout, the system eliminates dedicated readout lines for ancilla qubits, thereby reducing noise sources while maintaining full readout capability. This combining approach allows multiple qubit types to share common control and measurement resources.
Solution Approach 2:
The patent implements a universal readout resonator that serves both primary qubits and ancilla qubits. This single resonator structure performs multiple functions: reading out states of primary qubits, reading out states of ancilla qubits, and mediating interactions between different qubit types. The resonator is designed to couple with both qubit types simultaneously, creating a multi-functional interface that reduces overall system complexity and noise.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces the number of readout devices required, increases qubit density, and enables scalable quantum computing by allowing two-qubit interactions with reduced complexity and noise, while maintaining coherence and robustness against environmental fields.
Implementation Method 1
a fixed-frequency ancilla qubit device capacitively coupled to a tunable-frequency primary qubit device
Data Source
AI summary
In a general aspect, a quantum computing system includes ancilla qubit devices. In some aspects, a quantum computing system includes a quantum processor cell that includes a superconducting quantum circuit system. The superconducting quantum circuit system includes a tunable-frequency primary qubit device; a flux-bias device coupled to the tunable-frequency primary qubit device; and a fixed-frequency ancilla qubit device. The fixed-frequency ancilla qubit device is connected only to the tunable-frequency primary qubit device in the superconducting quantum circuit system. The quantum computing system also includes a control system communicably coupled to the quantum processor cell. The control system is configured to apply a parametrically-activated two-qubit quantum logic gate to the tunable-frequency primary qubit device and the fixed-frequency ancilla qubit device by sending, to the flux-bias device, a radio-frequency control signal that modulates the tunable-frequency primary qubit device.