Mode-Selective Superconducting Qubit Coupling for ZZ Suppression
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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 resonator to entangle them based on control signals, suppressing ZZ interactions and reducing energy loss, thereby improving quantum gate performance and enabling scalable quantum computing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If qubits are coupled via a bus resonator, then quantum gate operations can be performed, but residual ZZ interactions occur between qubits causing frequency shifts and reduced fidelity
Solution Approach 1:
The qubit coupling is segmented into two independent oscillating modes: a first mode for quantum information storage and a second mode for bus resonator coupling. This segmentation allows the bus to mediate quantum gate operations without creating harmful ZZ interactions between qubits in the computational mode, thereby maintaining both gate operation capability and quantum fidelity.
Solution Approach 2:
The bus resonator serves as an intermediary that couples to the second oscillating mode of qubits rather than directly to the computational mode. This intermediary coupling mechanism enables quantum gate operations while isolating the computational mode from harmful direct ZZ interactions, preserving quantum operation fidelity.
2Ease of operation
If qubits are coupled to a bus resonator, then quantum operations can be performed, but energy loss and decoherence increase due to internal losses and external energy leakage
Solution Approach 1:
The qubit's oscillating modes are segmented into a first mode for information storage with low loss and a second mode for bus coupling that handles energy exchange. This segmentation confines energy loss to the non-computational second mode, protecting the computational first mode from decoherence while maintaining quantum operation capability.
Solution Approach 2:
The bus resonator acts as an intermediary that interfaces with the second oscillating mode, providing a controlled pathway for energy exchange during quantum operations. This intermediary mechanism manages energy loss systematically rather than allowing direct coupling losses to affect the computational mode, reducing overall decoherence.
3Reliability
If mode-selective coupling is implemented to suppress ZZ interactions, then quantum fidelity improves, but device complexity increases
Solution Approach 1:
Each qubit is segmented into two oscillating modes with distinct functions: the first mode for computational operations and the second mode for bus coupling. This segmentation naturally suppresses ZZ interactions in the computational mode while enabling controlled coupling through the second mode, improving fidelity without requiring additional complex control mechanisms.
Solution Approach 2:
The two-junction qubit structure provides multi-functionality by supporting both computational operations and bus coupling through its two oscillating modes. This universal design eliminates the need for separate coupling mechanisms, achieving ZZ interaction suppression and energy control without proportionally increasing device complexity.
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
The solution effectively reduces quantum gate errors, increases the speed of quantum operations, and enhances the fidelity and accuracy of quantum processors by suppressing ZZ interactions and minimizing energy loss associated with the bus resonator.
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
A device comprising a superconducting bus resonator and two-junction qubits with mode-selective coupling
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.