Qubit Chip Mode Frequency Separation to Reduce Purcell Loss
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Solution Overview
Problem
In quantum computing, substrate chip modes often couple with qubit frequencies, leading to decoherence and reduced coherence times (T1 and T2 relaxation), which hinders the performance of quantum operations.
Innovation Solution
The method involves determining and controlling the separation between qubit frequencies and chip mode frequencies by applying a metal coating to the substrate edges, which shifts the chip resonant frequencies to higher values, and optimizing the chip dimensions to minimize Purcell loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is used as a microwave resonator with chip resonant modes close to qubit frequency, then the qubit experiences coupling with chip modes causing decoherence (Purcell loss), but using the substrate as a resonator structure provides mechanical support and electrical isolation
Solution Approach 1:
The patent changes the frequency parameter of the chip modes by modifying the substrate structure (adding metal coatings to edges) to shift chip resonant frequencies away from qubit operating frequencies. This parameter change reduces the coupling between qubits and chip modes, thereby reducing Purcell loss and improving qubit coherence time
Solution Approach 2:
The patent introduces an intermediary structure (metal coating on substrate edges) that modifies the electromagnetic boundary conditions of the substrate. This intermediary element shifts the chip mode frequencies without directly interacting with the qubits, thereby mediating the reduction of Purcell loss while maintaining the substrate's structural function
2Reliability
If metal coating is applied to substrate edges to shift chip resonant frequencies, then Purcell loss is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The metal coating is applied to the substrate edges during the fabrication process before the qubits are assembled or operated. This preliminary action ensures that the chip mode frequencies are shifted to the desired values before the qubits begin operation, integrating the frequency tuning into the manufacturing workflow rather than requiring post-fabrication adjustments
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 increases the coherence time (T1) of qubits by reducing coupling with chip modes, thereby enhancing the stability and performance of quantum operations.
Implementation Method 1
The substrate, typically formed of an insulating material with a high dielectric constant, may be viewed as a microwave resonator with chip resonant modes (chip modes) that may be close to the qubit frequency such that they couple with the qubit frequency and cause decoherence
Data Source
AI summary
A system, method, and chip to control Purcell loss are described. The chip includes qubits formed on a first surface of a substrate. The method includes determining frequencies of the qubits, and controlling a separation between the frequencies of the qubits and chip mode frequencies of the chip.