Transmon-Coupled Multi-Mode Qubits for Low-Noise ZZ Entangling Gates
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Solution Overview
Problem
Existing quantum entangling gate technologies in quantum computing face issues with unwanted multi-photon transitions and dephasing due to strong microwave drives, and sensitivity to flux noise in flux-tunable buses, which hinder efficient entanglement between multi-mode superconducting qubits.
Innovation Solution
A transmon coupler is used to establish a quantum entangling gate between multi-mode superconducting qubits, allowing for controlled ZZ interactions without the need for strong microwave drives or flux-tunable buses, by employing a transmon qubit that suppresses or enhances the static ZZ interaction via excitation or de-excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong microwave drives are used to establish quantum entanglement, then entanglement can be created between superconducting qubits, but unwanted multi-photon transitions and dephasing occur
Solution Approach 1:
A transmon qubit is introduced as an intermediary between the two multi-mode superconducting qubits to mediate the ZZ interaction. This intermediary approach allows entanglement to be established through controlled coupling via the transmon qubit's excitation states, avoiding the need for strong microwave drives that cause multi-photon transitions and dephasing.
Solution Approach 2:
The system utilizes parameter changes in the transmon qubit's excitation state (ground state vs. excited state) to dynamically control the strength and nature of the ZZ interaction between the multi-mode qubits. By changing the transmon qubit's state, the coupling parameter is modulated, enabling precise control of entanglement without harmful strong drives.
2Reliability
If flux-tunable buses are used to establish quantum entanglement, then entanglement can be created between superconducting qubits, but sensitivity to flux noise increases
Solution Approach 1:
The transmon qubit serves as a mediator that replaces the flux-tunable bus in establishing ZZ interactions. This intermediary approach eliminates the direct need for flux-tunable coupling elements, thereby reducing sensitivity to flux noise while maintaining the ability to create entanglement through controlled quantum interactions.
Solution Approach 2:
The patent replaces the flux-tunable bus mechanism (which relies on magnetic flux control) with a transmon qubit-based coupling mechanism. This substitution transitions from a flux-controlled system to a quantum-state-controlled system, reducing sensitivity to flux noise while preserving entanglement creation capability.
3Manufacturing precision
If transmon coupler is used to control ZZ interaction, then cross-talk is reduced and gate accuracy is improved, but device complexity increases
Solution Approach 1:
The transmon qubit serves multiple functions: it acts as both a computational qubit and a coupling mediator for ZZ interactions. This multi-functionality allows a single quantum element to perform dual roles, reducing the need for separate dedicated coupling components and thereby managing device complexity while improving gate accuracy and reducing cross-talk.
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 facilitates low cross-talk and fast, accurate two-qubit entangling gates, reducing unwanted transitions and noise sensitivity, thereby enhancing the reliability of quantum computations.
Implementation Method 1
a first multi-mode superconducting qubit coupled to a second multi-mode superconducting qubit via a transmon qubit
Data Source
AI summary
Techniques regarding a quantum entangling gate between multi-mode superconducting qubits are provided. For example, one or more embodiments described herein can comprise an apparatus, which can comprise a first multi-mode superconducting qubit coupled to a second multi-mode superconducting qubit via a transmon qubit.