Mode-Selective Bus Coupling for ZZ-Suppressed Superconducting Qubits
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Solution Overview
Problem
Existing quantum devices with two-junction superconducting qubits experience residual ZZ interactions and energy loss due to coupling with a bus, which inhibit fidelity and introduce decoherence, and prior technologies fail to effectively suppress static ZZ interactions while enabling longitudinal coupling.
Innovation Solution
A device comprising a superconducting bus resonator and two-junction qubits with mode-selective coupling, where the qubits' pads are coupled to the bus resonator to entangle them based on control signals, thereby suppressing ZZ interactions and reducing energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If qubits are coupled via a bus, then quantum gate operations can be performed, but residual ZZ interactions occur that reduce fidelity
Solution Approach 1:
The qubit coupling is segmented into multiple independent coupling paths: direct qubit-to-qubit coupling and separate qubit-to-bus coupling. This segmentation allows independent control of interaction strengths, enabling gate operations through direct coupling while suppressing unwanted ZZ interactions through the bus by adjusting coupling parameters separately.
Solution Approach 2:
The bus resonator serves as an intermediary that mediates quantum gate operations between qubits. By controlling the bus coupling strength and operating conditions, the bus enables gate operations while the direct coupling path provides an alternative route that can be tuned to minimize harmful ZZ interactions that would otherwise occur through bus-mediated coupling.
2Ease of operation
If qubits are coupled to a bus, then coupling operations are enabled, but energy loss and decoherence increase
Solution Approach 1:
The coupling architecture is segmented into direct qubit-qubit coupling and separate qubit-bus coupling channels. This allows quantum operations to be performed primarily through the direct coupling path, which has lower energy loss, while the bus coupling is minimized or tuned off during operations to reduce energy dissipation and decoherence effects.
Solution Approach 2:
The coupling strength parameters are dynamically adjusted: direct coupling strength is optimized for gate operations with minimal energy loss, while bus coupling strength is reduced or tuned to specific values that minimize energy dissipation and decoherence. This parameter optimization allows maintaining operational capability while reducing energy loss.
3Adaptability or versatility
If two-junction qubits are used for tunable coupling, then coupling flexibility is improved, but ZZ interactions are not suppressed
Solution Approach 1:
The coupling mechanism is segmented into direct capacitive coupling between qubits and separate bus-mediated coupling paths. The direct coupling provides the primary tunable interaction for gate operations, while the bus coupling is configured to minimize ZZ interactions. This segmentation allows maintaining coupling flexibility through direct coupling tuning without suffering from the ZZ interaction problems that plague bus-mediated coupling alone.
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 approach reduces quantum gate errors, increases the speed of quantum gates, and improves the fidelity and accuracy of quantum processors by minimizing ZZ interactions and energy loss, enabling the development of logical qubits and scalable quantum computers.
Implementation Method 1
a first Josephson Junction coupled to the first superconducting pad and the second superconducting pad; and a second Josephson Junction coupled to the second superconducting pad and the third superconducting pad
Implementation Method 2
The superconducting bus resonator entangles the first superconducting qubit and the second superconducting qubit based on receiving a control signal
Implementation Method 3
suppress ZZ interactions between a first oscillating mode of both the first superconducting qubit and the second superconducting qubit
Data Source
AI summary
Devices and/or computer-implemented methods facilitating static ZZ suppression and Purcell loss reduction using mode-selective coupling in two-junction superconducting qubits are provided. In an embodiment, a device can comprise a superconducting bus resonator. The device can further comprise a first superconducting qubit. The device can further comprise a second superconducting qubit, the first superconducting qubit and the second superconducting qubit respectively comprising: a first superconducting pad; a second superconducting pad; a third superconducting pad; a first Josephson Junction coupled to the first superconducting pad and the second superconducting pad; and a second Josephson Junction coupled to the second superconducting pad and the third superconducting pad. The first superconducting pad and the second superconducting pad of the first superconducting qubit and the second superconducting qubit are coupled to the superconducting bus resonator. The superconducting bus resonator entangles the first superconducting qubit and the second superconducting qubit based on receiving a control signal.